1970 C3 Corvette

1970 C3 Corvette Overview

The arrival of the 1970 Corvette happened somewhat later than was typical in the automotive manufacturing industry, due in part to the incredible sales backlog that had occurred during the 1969 model year and also due in part to the UAW (United Workers) strike, which delayed the new Corvette from reaching showrooms until February.

The decision to prolong the ‘69’s production had been made by then Chevrolet President, John Z. DeLorean, who had taken the helm of the company on February 1, 1969.  Along with the Camaro and the Pontiac Firebird, DeLorean believed that prolonging production of the earlier models into the winter of 1969-70 would help Chevrolet make up ground on an order backlog that had occurred in part because of the two-month automotive workers strike at GM plants early in 1969.

Model: 1970 Corvette
Generation: C3 Corvette
Type: 2 Door Coupe/Convertible
Available Colors: Classic White, Monza Red, Marlboro Maroon, Mulsanne Blue, Bridgehampton Blue, Donnybrooke Green, Daytona Yellow, Cortez Silver, Ontario Orange, Laguna Gray, Corvette Bronze
Engine: 350ci – 300HP Engine (standard),  350ci – 370HP Engine, 454ci – 390HP Engine
VIN: 194370S400001 – 194370S417316
Transmission: 3-speed manual (standard), 4-speed manual (optional), 3-speed Turbo Hydra-Matic automatic (optional)
Original Price: $5,192.00 (Coupe), $4,849.00 (Convertible)
Units Produced: 17,316
Specs 1970 Corvette Spec List
John DeLorean
John DeLorean became president of Chevrolet in 1970 and was responsible for significantly increasing the price of the Corvette.

It was because of this extension that the 1969 Corvette had set record sales numbers for the model year.
On November 7, 1969, Chevrolet manufactured its 250,000th Corvette since production of the sports car had begun on June 30, 1953.  Although technically the model should have been a 1970 Corvette, it was still recognized as a 1969 because of the aforementioned production extension.  The car, which rolled off the production line at 10:32 a.m., was a convertible painted in Riverside Gold.  The car was originally purchased by George Dyer of Montebello, California.

Interestingly, the 1970 Corvette’s arrival would come at a time when, despite the Corvette’s incredible popularity, it was simultaneously falling under increasing scrutiny for its general lack of overall production value and build quality.

In 1970, Road & Track Magazine surveyed 177 Corvette owners and found most agreed that “the worst thing about Corvettes, according to the owners, is the workmanship – or the lack of it.

Whereas 18% of the owners of 196367 models considered workmanship the worst feature of the car, an astounding 40% had that comment to make about the 196869 models!  Seventeen percent of the owners of both series listed squeaks and rattles as the worst feature.”

While to diminish the demand for the Corvette in any way, Chevrolet recognized that this issue presented a genuine challenge for them.

Road & Track Magazine, March, 1970.
Road & Track Magazine, March, 1970.

In order to keep up with demand, GM had been forced to add a third shift in their St. Louis plant to keep production on schedule.

Despite the realizations of production quality being compromised, the result of such high volume (for both the 1968 and 1969 model years, as well as the preparatory work for the 1970) was that quality control was barely able to hold its own, let alone have any chance of improving.  It was during this time period that production quality had reached an all-time low.

The 1970 Corvette actually made its formal debut in late February, and introduced the world to a number of small, but improved design styling touches.  These design changes, which had been introduced on a show car known simply as the Aero Coupe, had included many elements which suggested that the designers were looking to move away from Corvette’s current role as a pure sports car (the ZL-1 notwithstanding) and more towards the blended role of becoming a Luxury Sports car.

The Aero Coupe had featured an egg-crate patterned grille, matching louvers along the fenders (which replaced the four gills of the 1968 and 1969 model years), and more deeply flared wheel house introduced to reduce the severity of the bodyside tuck-under, which had been discovered as being susceptible to stone damage.

The exterior of the 1970 Corvette also featured a number of other design cues that were new for the model year.  Amongst these, the parking lights were now squared off and set into the corners of the grille. Mandatory side marker lights at the front and rear of the car were larger and better integrated into the design than those of earlier model years.  In the back of the car, new rectangular exhaust pipe tips were recessed into the underside of the tail in a manner inspired by the Mako Shark II.  A number of detail refinements were also made to the taillights and the stainless steel rocker moldings.

1970 Corvette Aero Coupe
The 1970 Corvette Aero Coupe started as a stock 1968 Corvette and was modified by Bill Mitchell to preview the 1970 1/2 styling changes. (Image courtesy of GM Media.)
1970 Corvette grille
The fender louvers changed on the 1970 Corvette, featuring an egg-crate patterned grille.
Corvette custom interior 1970
Though not designated with an RPO option code, the 1970 Corvette custom interior was an additional $158.00 option that dressed up the interior of the Corvette.

The interior of the 1970 Corvette was improved upon in a number of areas.  The seats, which had been re-designed in 1969, underwent another design change that added an inch of urgently needed headroom as well as better lateral support.

Additionally, the headrests were integrated into the seat design and a more accessible release button was introduced for the seat back hinge.  The inertia reels for the shoulder harnesses were tucked away more neatly in the rear quarters, thereby opening up more space in the trunk area.  The seatbelts themselves were now being fed through slots in the seat backs that made them feel built into the design.

A new option was introduced for the 1970 Corvette that could be ordered at a small, added cost to the customer.

The “custom interior” option, though it had no separate RPO code associated with it, sold for an additional $158.00 on top of the base coupe or convertible price.  The custom interior gave the Corvette a “dressed-up” look, a subtle touch of plushness that offset the minimalist character of the usual Corvette interior.  Leather-trimmed seats, cut-pile, door-to-door carpeting, a leather boot (for manual transmission shift levers), and wood-grain trim on the console and doors were all introduced to provide an additional layer of warmth to the interior of the 1970 Corvette.

The previously optional Soft-Ray Tinted Glass option (RPO A01) was made standard equipment for the 1970 model year.  As a result, all 1970 Corvettes received evenly tinted glass on all windows.

In addition to the window tint, a number of other options were made standard for the 1970 model year including Positraction differentials (formerly RPO G81) and the four-speed manual transmission (formerly RPO M20/M21), of which consumers could choose to install wide-ratio, close-ratio, or have it swapped all together for the Turbo Hydra-Matic at no additional cost.

 1970 LT-1 Engine
The 1970 LT-1 Engine. (Image courtesy of GM Media.)

Mechanically, there were many carryovers from the previous model year.  The small-block engine lineup remained the same at the two lower power ratings (300 horsepower and 350 horsepower respectively). However, GM did introduce a new solid-lifter, small block engine that they designated the LT-1.

Corvettes equipped with this engine received a special hood dome surrounded by striping and “LT-1” lettering.  While these markings were certainly a differentiator between which engine a particular Corvette was built with, it was also readily obvious to anyone who heard the unique rumble from the exhaust pipes and the tapping of its mechanical lifters that they were in the presence of an LT-1 engine.

Corvettes equipped with the LT-1 engine also came standard with a larger bore – two-and-a-half inch – exhaust system, and a larger carburetor – an 850 CFM Holley four-barrel with vacuum controlled secondary throttles.  Although only a small-block, the Holley four-barrel was actually the same carburetor that GM had specified for Corvette’s big-block engine setups.  In conjunction with the massive fuel delivery system, Corvette engineers also included a transistorized Delco ignition system, which helped produce reliable high-speed operation (with a redline of 6,500 rpm) in the LT-1 engine.

"LT-1"lettering.
Corvettes equipped with the LT-1 engine received a special hood dome surrounded by striping and “LT-1″lettering.

The numbers that the LT-1 engine produced were impressive, and certainly consistent with the performance expectations that individuals like Zora Arkus-Duntov had for the Corvette.

The LT-1 equipped Corvettes could manage a quarter mile run in just 14.2 seconds with a top speed of 102 miles per hour, indicating that GM’s published ratings of 370 BHP (brake horsepower) at 6,000rpm and 380lb/ft of torque at 4,000rpm were both on the conservative side.

In point of fact, the LT-1 engine was actually specified for use in the SCCA’s Class B Production car series.  For racers wishing to purchase a Corvette so equipped, they would need look no further than the factory options order sheet, introduced that included the LT-1 engine as well as a cold-air hood and all of the relevant brake and chassis racing equipment.

1970 454 Cubic-Inch Big Block Engine
The 1970 454 Cubic-Inch Big Block Engine. (Image courtesy of GM Media.)

Of course, many racers looking to utilize the performance and handling aspects of the Corvette were not going to invest their money into a small-block, despite the performance numbers it was capable of producing.

Serious racers knew that, if they were able to sort through the options presented to them, they should have been able to assemble a race car that would rival anything on the track.   While earlier Corvettes were capable of being equipped with such options as the ZL-1, (which featured a setup that included the 427 cubic inch L88 engine,) the 1970 offerings were a little harder to come by.

For the 1970 model year, Chevrolet introduced a big block 427 that was stroked out to a full 4.00 inches and 454 cubic inches.  It was the first time that the stroke had been increased since the engine had been introduced in its more conservative iteration – a 396 cubic-inch big block – in 1965.  While the arrival of the 454 was considered by some to be in response to Corvettes increasing presence on the racetrack, the truth is actually more intriguing.  The added cubic inches in the Corvette were actually the byproduct of Chevy’s need to expand the engine’s size to counterbalance the loss of performance in its regular passenger cars due to the mandatory reductions in exhaust emissions as required by state and federal laws.

Still, there was the question of how racers could build a serious track car by using the right combination of production codes.   The aforementioned L88 and ZL1 options were even offered for 1970 (though Chevy continued to sell Can-Am engines to bona fide race teams).  Instead, GM announced that it would be offering two big-block options: RPO LS5 and LS7.  The LS5 would come equipped with hydraulic lifters, 10.25:1 compression, a single, four-barrel carburetor, and was rated at 390 bhp (at 4,800 rpm) with a massive 500lbs/ft of torque.

DID YOU KNOW: In 1970, big block engines increased from 427 to 454 cubic inches and the powerful 370 HP LT1 small block engine made its debut. Also, the first ZR1 performance package appeared in 1970 (not 1990, as some might believe) and included the 370 HP LT1 engine and a host of other performance items.

The LS7, on the other hand, became known merely as a “legendary engine”.   GM did publish specs on the LS7 engine, and articles about the engine were published in many automobile magazines, but the engine itself was never made available for purchase.

That’s not to say that the engine never came into being.  Quite to the contrary, GM did produce an LS7 equipped Corvette in December, 1969 that was driven from Los Angeles to Detroit by Paul Van Valkenburgh, a writer from the magazine Sports Car Graphic.  He stated that, “with a full tank, two aboard and a full load of luggage the car would still turn the standing quarter mile in 13.8 seconds with a top speed of 108 miles per hour.”  He further went on to write that “never have we tested a car that had such a secure speed potential.  This car gives the impression that it could do anything you demanded.”  Depending on the source of information, the LS7 engine’s output was rated at either 460 or 465 horsepower.

Exterior Features Interior Features
Functional front fender louvers.
Hide-A-Way windshield wipers
Wide-oval F70x15 tires and 15×8 wheels.
Body sill moldings
Wheel trim rings and center caps.
Bright roof drip and rear window molding
Flush mounted door handles.
Removable roof panels and rear window.
Astro-ventilation outlet grilles on rear deck
Twin unit taillights/backlights with bright bezels.
Wrap around rear bumper with built-in guards
Bright outlined front fender louvers
Sports-styled steering wheel with black rim
7000-rpm tachometer
Anti-theft steering column lock
Ammeter, temp,  fuel, & oil pressure gauges
Light monitoring system alert panels
Seat belt, door and light position indicators
Luxurious all-vinyl interior styling
High-back, slim-tapered bucket seats
Utilized seat and shoulder belt buckle design
Tinted glass in all windows
Molded door panels with built-in armrests
Full door-glass styling and Astro Ventilation
Folding seat back latches
Custom-Deluxe color-matched seat belts
Handy map and storage pockets
Glare-resistant padded instrument panel
Parking brake and brake system warning light
Seat belt retractors
Deep-twist, color-keyed floor carpeting
Courtesy lights with automatic door switches
Suspended accelerator pedal
Carpeted rear compartment storage wells
Removable roof panels
Vinyl plastic rear window

Unfortunately for Corvette owners, the LS7 engine program was cancelled by GM’s own internal discouragement of producing cars with excessively high horsepower (which is ironic because at the time the decision was made, Ed Cole (one of the engineers behind the very first Corvette) was president of General Motors and would have been capable of overruling that decision).  In addition, Chevrolet had begun a campaign to “weed out” costly options that would clog up their assembly lines.  This campaign became known as the “de-proliferation” program.  The LS7 fell prey to the “de-pro” program, and ceased its existence almost before it had begun.

The 1970 Corvette was one of the first cars during John DeLorean’s tenure as President of General Motors to fall prey to a new pricing plan that took advantage of the car’s unprecedented popularity.  DeLorean contested that since each year’s production quota was usually spoken for, and secured by concrete dealer and buyer orders (usually in as early as March or April), that it seemed reasonable that General Motors should actually increase the price of the Corvette more substantially than it had in previous year – and that is exactly what happened.

1970 Corvette Ads
GM Advertisement for the 1970 Corvette. (Image courtesy of GM Media.)

Corvette prices jumped dramatically from the mid-$4000 price range in 1969 (depending on coupe or convertible (see 1969 Specifications Page for more information)), to over $5000 in 1970.  The base coupe (without extra options) now retailed for $5,192.00.

The convertible on the other hand, while still somewhat less expensive, sold for $4,849.00.  While the sudden price increase doubtless had some impact on some customers’ willingness to purchase a new Corvette, it was really the late production start as the result of the UAW strike which most adversely impacted the total sales numbers on the 1970 Corvette.  The coupe sold just 10,668 units, whereas the convertible sold an abysmal 6,648 1970 saw the sale of only 17,316 Corvettes, which was the lowest sales number for Corvette since 1962.

1970 Corvette

Road & Track Magazine tested an LS5 equipped Corvette with an automatic transmission and was able to manage a 0-60 time of 7.0 seconds, a quarter-mile time of 15.0 seconds at 93 miles per hour, and a top speed of 144 miles per hour.  While these performance numbers were impressive, the testers criticized the suspension, complaining that it “suffered from both excessive harshness over irregular surfaces and a certain flatness at speed.”

While these criticisms were certainly noteworthy, they also turned out to be irrelevant.  The 1970 model year would mark the end for the big-block, high-power Corvettes as they had been known up to this point.  A number of factors played into this decision, including skyrocketing insurance rates and a large decline in the sale of sports cars, but the largest contributing factor was a decision made by GM President Ed Cole’s desire to eliminate low-volume options.  Further, he dictated that all engines would be required to be able to run on 91-octane fuel, a decision that was made because of the anticipation of the ever tightening emission regulations that would govern future automotive production.


See full 1970 Corvette Image Gallery


1970 Corvette Specifications

1970 Corvette Main Specs

MODEL: 1970 Chevrolet Corvette
BODY STYLE: Two-door convertible/coupe, front engine, rear wheel drive
MANUFACTURING LOCATION: St. Louis, Missouri
CONSTRUCTION: Uniconstruction: fiberglass reinforced plastic (FRP or “fiberglass”) body, backboned by a steel cage outlining the passenger compartment. Principal members – underbody, front and rear end assemblies, dash panel and hinge pillars are bonded, riveted, or bolted together and to each other. Hood is plastic with bonded plastic reinforcement. Coupe: two removable roof panels and removable rear window. Frame: all welded, full length, ladder construction with 5 crossmembers. Side Rails and intermediate crossmembers box section; front crossmember box girder section. Eight body-mounting points.
VEHICLE NUMBERS (VIN): 194370S400001 – 194370S417316
ENGINE SUFFIX: CGW: 454 CUBIC INCH, 390 HORSEPOWER, AUTOMATIC TRANSMISSION
CRJ: 454 CUBIC INCH, 390 HORSEPOWER, AUTOMATIC TRANSMISSION, TRANSISTOR IGNITION
CRI: 454 CUBIC INCH, 390 HORSEPOWER, MANUAL TRANSMISSION, TRANSISTOR IGNITION
CTD: 350 CUBIC INCH, 300 HORSEPOWER, MANUAL TRANSMISSION
CTG: 350 CUBIC INCH, 300 HORSEPOWER, AUTOMATIC TRANSMISSION
CTH: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMISSION
CTJ: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMISSION, AIR CONDITION
CTK: 350 CUBIC INCH, 370 HORSEPOWER, MANUAL TRANSMISSION, TRANSISTOR IGNITION
CTL: 350 CUBIC INCH, 300 HORSEPOWER, MANUAL TRANSMISSION
CTM: 350 CUBIC INCH, 300 HORSEPOWER, AUTOMATIC TRANSMMISSION
CTN: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMMISSION
CTO: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMMISSION,AIR CONDITIONING
CTP: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMMISSION, TRANSISTOR IGNITION
CTQ: 350 CUBIC INCH, 350 HORSEPOWER, MANUAL TRANSMMISSION, AIR CONDITIONING, TRANSISTOR IGNITION
CTR: 350 CUBIC INCH, 370 HORSEPOWER, MANUAL TRANSMMISSION, TRANSISTOR IGNITION
CTU: 350 CUBIC INCH, 370 HORSEPOWER, MANUAL TRANSMMISSION, TRANSISTOR IGNITION
CTV: 350 CUBIC INCH, 370 HORSEPOWER (ZR1), MANUAL TRANSMMISSION
CZU: 454 CUBIC INCH, 390 HORSEPOWER, MANUAL TRANSMMISSION
ENGINE BLOCK NUMBER: 3970010, 350 CUBIC INCH, 300 HP, 350HP, 370HP
3963512, 454 CUBIC INCH, 390 HP
HEAD NUMBER: 3927186, 350 CUBIC INCH, 300HP, 350HP, 370HP
3927187, 350 CUBIC INCH, 350HP
3964290, 454 CUBIC INCH, 390HP
3973414, 350 CUBIC INCH, 370HP
CARBURETOR NUMBERS: ROCHESTER Q-jet #7040202: 350 CUBIC INCH, 300HP, AUTO
ROCHESTER Q-jet #7040203: 350 CUBIC INCH, 300HP, MANUAL
ROCHESTER Q-jet #7040204: 454 CUBIC INCH, 390HP, AUTO
ROCHESTER Q-jet #7040205: 454 CUBIC INCH, 390HP, MANUAL
ROCHESTER Q-jet #7040207: 350 CUBIC INCH, 350HP, MANUAL
ROCHESTER Q-jet #7040212: 350 CUBIC INCH, 300HP, AUTO
ROCHESTER Q-jet #7040213: 350 CUBIC INCH, 300HP, MANUAL
ROCHESTER Q-jet #7040502: 350 CUBIC INCH, 300HP, AUTO
ROCHESTER Q-jet #7040503: 350 CUBIC INCH, 300HP, MANUAL
ROCHESTER Q-jet #7040504: 454 CUBIC INCH, 390HP, AUTO
ROCHESTER Q-jet #7040505: 454 CUBIC INCH, 390HP, MANUAL
ROCHESTER Q-jet #7040507: 350 CUBIC INCH, 350HP, MANUAL
ROCHESTER Q-jet #7040513: 350 CUBIC INCH, 300HP, MANUAL
HOLLEY R4489A #3972123: 350 CUBIC INCH, 370HP, MANUAL
HOLLEY R4555A #3972121: 350 CUBIC INCH, 370HP, MANUAL
DISTRIBUTOR NUMBER: 1111464: 454 CUBIC INCH, 390HP
1111490: 350 CUBIC INCH, 300HP
1111491: 350 CUBIC INCH, 370HP, TRANSISTOR IGNITION
1111493: 350 CUBIC INCH, 350HP
1112020: 350 CUBIC INCH, 300HP
1112021: 350 CUBIC INCH, 350HP
ALTERNATOR NUMBER: 1100825: 350 CUBIC INCH, 370HP
1100833: 350 CUBIC INCH 350HP, 454 CUBIC INCH 390HP
1100859: 350 CUBIC INCH, 300HP
AXLE IDENTIFICATION NUMBER CAK: 3.36:1 RATIO
CAL: 3.08:1 RATIO
CAN: 3.55:1 RATIO
CAP: 4.11:1 RATIO
CAS: 3.70:1 RATIO
CAV: 3.08:1 RATIO
CAW: 3.08:1 RATIO
CLR: 3.36:1 RATIO
POSITRACTION AXLE:
CAM: 3.36:1 RATIO
CAO: 3.70:1 RATIO
CAT: 3.08:1 RATIO, HEAVY DUTY
CAU: 3.36:1, HEAVY DUTY
CAX: 3.36:1, HEAVY DUTY
CAY: 2.73:1 RATIO, TURBO HYDRA-MATIC TRANSMISSION
CAZ: 3.55:1 RATIO, HEAVY DUTY
CFA: 3.70:1 RATIO
CFB: 4.11:1 RATIO, HEAVY DUTY
CFC: 4.56:1, HEAVY DUTY
PRODUCTION ENDING VEHICLE: JANUARY 1979:402261, FEBRUARY 1970: 405183, MARCH. 1970: 407977, APRIL. 1970: 408314, MAY 1970: 410652, JUNE 1970: 413829, JULY 1970: 417316

1970 Corvette Pricing & Options

CODE:
DESCRIPTION:
QUANTITY:
RETAIL PRICE:
19437
Base Corvette Sport Coupe
10,668
$5,192.00
19467
Base Corvette Convertible
6,648
$4,849.00
Custom Interior Trim
3,191
$158.00
A31
Power Windows
4,813
$63.20
A85
Custom Shoulder Belts (std with coupe)
475
$42.15
C07
Auxiliary Hardtop (for convertible)
2,556
$273.85
C08
Vinyl Covering (for auxiliary hardtop)
832
$63.20
C50
Rear Window Defroster
1,281
$36.90
C60
Air Conditioning
6,659
$447.65
G81
Optional rear Axle Ratio
2,862
$12.65
J50
Power Brakes
8,984
$47.40
L46
350ci 350hp Engine
4,910
$158.00
LS5
454ci 390hp Engine
4,473
$289.65
LT1
350ci 370hp Engine
1,287
$447.60
M21
4-Speed Manual Transmission, Close-Ratio
4,383
$0.00
M22
4-Speed Manual Transmission, Close Ratio Heavy Duty
25
$95.00
M40
Turbo-Hydro-matic Automatic Transmission
5,102
$0.00
NA9 California Emissions 1,758 $36.90
N37
Tilt-Telescopic Steering Column
5,803
$84.30
N40 Power Steering 11,907  $105.35
P02
Deluxe Wheel Cover
3,467
$57.95
PT7  White Stripe Tires, F70x15, Nylon 6,589 $31.30
PU9
White Letter Tires, F70x15, Nylon
7,985
$33.15
T60
Heavy Duty Battery (std with LS5)
165 $15.80
UA6 Alarm System 6,727 $31.60
U69
AM-FM Radio
14,529 $172.75
U70
AM-FM Radio, stereo
2,462 $278.10
ZR1
Special Purpose Engine Package
25 $968.95

1970 Corvette

1970 Corvette Exterior & Interior Colors

Exterior Colors

CODE
EXTERIOR
SOFT TOP
WHEELS
INTERIOR
972
Classic White
Black, White, Sandalwood
Silver
Black, Blue, Brown, Green, Red, Saddle
974
Monza Red
Black, White, Sandalwood
Silver
Black, Brown, Red, Saddle
975
Marlboro Maroon
Black, White, Sandalwood
Silver
Black, Brown, Saddle
976
Mulsanne Blue
Black, White, Sandalwood
Silver
Black, Blue
979
Bridgehampton Blue
Black, White, Sandalwood
Silver
Black, Blue
982
Donnybrooke Green
Black, White, Sandalwood
Silver
Black, Brown, Green, Saddle
984
Daytona Yellow
Black, White, Sandalwood
Silver
Black, Green
986
Cortez Silver
Black, White, Sandalwood
Silver
Black, Blue, Brown, Green, Red, Saddle
991
Ontario Orange
Black, White, Sandalwood
Silver  Black, Saddle
992
Laguna Gray
Black, White, Sandalwood  Silver Saddle
993
Corvette Bronze
Black, White, Sandalwood  Silver Black, Blue, Brown, Green, Red, Saddle

Interior Colors (Vinyl & Leather)

INTERIOR COLOR CODES (VINYL):
INTERIOR COLOR CODES (LEATHER):
Black (Vinyl)
400
Black (Leather)
403
Red (Vinyl)
407
Saddle (Leather)
424
Blue (Vinyl)
411
Brown (Vinyl)
414
Saddle (Vinyl)
 418
 Green (Vinyl) 422

Exterior Colors

1970 Corvette Colors

Interior Colors

1970 Corvette Colors Interior

1970 Corvette

1970 Corvette Powertrain Specifications

Order Code Standard L46 LT1
Manufacturing Location Flint, Michigan Flint, Michigan Flint, Michigan
Type 90 degree V, Valve-In-Head 90 degree V, Valve-In-Head 90 degree V, Valve-In-Head
Cylinders 8 8 8
Displacement (cid) 350 350 350
Fuel Induction System 4-Barrel Carburetor 4-Barrel Carburetor 4-Barrel Carburetor
Horsepower 300 @ 4,800 350 @ 5,600 370 @ 6,000
Torque 380 @ 3,200 380 @ 3,600 380 @ 4,000
Bore x Stroke (in.) 4.00 x 3.48 4.00 x 3.48 4.00 x 3.48
Compression Ratio 10.0:1 11.0:1 11.0:1
Firing Order 1-8-4-3-6-5-7-2 1-8-4-3-6-5-7-2 1-8-4-3-6-5-7-2
Cylinder Number System (Left) 1-3-5-7 1-3-5-7 1-3-5-7
Cylinder Number System (Right) 2-4-6-8 2-4-6-8 2-4-6-8
Recommended Fuel Premium Premium Premium
Order Code LS5 LS7
Manufacturing Location Flint, Michigan Flint, Michigan
Type 90 degree V, Valve-In-Head 90 degree V, Valve-In-Head
Cylinders 8 8
Displacement (cid) 454 454
Fuel Induction System 4-Barrel Carburetor 4-Barrel Carburetor
Horsepower 390 @ 4,800 460 @ 5,600
Torque 500 @ 3,400 490 @ 3,600
Bore x Stroke (in.) 4.251 x 4.00 4.251 x 4.00
Compression Ratio 10.25:1 11.25:1
Firing Order 1-8-4-3-6-5-7-2 1-8-4-3-6-5-7-2
Cylinder Number System (Left) 1-3-5-7 1-3-5-7
Cylinder Number System (Right) 2-4-6-8 2-4-6-8
Recommended Fuel Premium Premium

1970 Corvette Manual Transmission/Gear Ratios

Manual Transmission

Gear Ratios 
4-Speed (RPO M20)
4-Speed Close Ratio (RPO M21)
4-Speed Heavy Duty (RPO M22)
1st Gear:
2.52:1
2.20:1
2.20:1
2nd Gear:
1.88:1
1.64:1
1.64:1
3rd Gear:
1.46:1
1.27:1
1.27:1
4th Gear:
1.00:1
1.00:1
1.00:1
Reverse:
2.59:1
2.26:1
2.26:1

Clutch

Clutch Stats
Type Single Dry Disk Centrifugal
Spring Pressure (lbs) 2450 – 2750 (2900 – 3100 Heavy Duty)
Lining area (sq. in.) 123.7 (103.53 Heavy Duty)

Turbo Hydra-Matic Automatic Transmission RPO M40/ Gear Ratios

Gear Drive L2 L1 Reverse
1st Gear 2.48:1 2.48:1 2.48:1 N/A
2nd Gear 1.48:1 1.48:1 N/A N/A
3rd Gear 1.00:1 N/A N/A N/A
Reverse N/A N/A N/A 2.08

1970 Corvette Wheels, Suspension & Brakes

Suspension – Front

Type and Description: Independent, SLA type, coil springs with center mounted shock absorbers, spherical joint steering knuckle pivots.

Front Coil Springs
Make & Type Right-hand Helix Variable rate
Material Steel Alloy
Part Number 3931823, 3931825
Spring Rate (lb. per in.) 250 (284)
Rate at Wheel (lb. per in.)
Design Load at Spring 9.99 in. @ 1395 lbs. (9.99 in. @ 1540 lbs.
Front Stabilizer Bar
Type Link
Material Hot rolled steel
Diameter .750 with 350ci engine, .9375 with 454ci engine

Suspension – Back

Type and Description: Full Independent rear suspension with frame-anchored differential unit. Position of each wheel established by three links: tubular axle drive shafts, transverse strut rods, torque control arms. Vertical suspension loads taken by transverse leaf springs. Built-in camber adjustment at strut rod inner ends.
Rear Leaf Springs
Number of Leaves 9
Material Chrome carbon steel
Length, width, height 46.36 x 2.25 x 2.121
Rear Shock Absorbers:
Type Direct, double-acting, hydraulic
Piston Diameter 1.00
Rear Strut
Material Forged Steel
Diameter 0.75

Brakes

Brake Specs
Type:
– Standard Caliper Disk – 4 Wheel Hydraulic
– J50 Delco-Moraine Vacuum Assisted Powered Brakes
Drum diameter, front (in.): 11.75 x 1.25
Drum diameter, rear (in.): 11.75 x 1.25
Swept Drum Area Effective area: 461.2

Wheels & Tires

Wheels & Tires Specs
Wheel Type:
– Standard Short spoke spider, welded steel
Wheels, size:
– Standard 15″ x 8.00
Tire, size:
– Standard F70 x 15 — 4 PR. 2-Ply Tubeless Nylon
– PT6 F70 x 15 — 4 PR, 2-Ply Red Stripe Nylon
– PT7 F70 x 15 — 4 PR, 2-Ply White Stripe Nylon
Inflation (cold)
– Front 24 lbs.
– Rear 24 lbs.

Steering

Steering Specs – Manual Steering
Type Semi-reversible gear with ball-nut driven by recirculating anti-friction bearings, energy-absorbing steering column, steering damper attached to relay rod; two position steering knuckle arm attachment for street and fast ratio steering. Adjustable steering column available optionally.
Make Saginaw
Ratio (Street) 20.2:1
Ratio (Fast) 17.6:1
Wheel Diameter (in.) 16
Turns, Stop to Stop
– Street 3.4
– Fast 2.92
Turning Diameter 37 ft. (outside front), 39 ft. (outside front)

 

Steering Specs – Power Steering RPO N40
Type (Specifications are the same as Manual Steering except the following):
Description Hydraulic; pump powered cylinder assisted linkage
Gear Ratio 16:1
Overall Ratio 17.6:1
Wheel Turns (Lock to Lock) 2.92

1970 Corvette

1970 Corvette Exterior Dimensions

Hard Top Dimensions

1970 Corvette Dimensions - Hard Top

Exterior Dimensions (Hardtop) Interior Dimensions (Hardtop)
Wheelbase: 98.0 Inches Headroom: 37.1 Inches
Overall Length: 182.1 Inches Shoulder Room: 46.9 Inches
Total Body Width: 69.2 Inches Hip Room: 48.8 Inches
Overall Height: 47.9 Inches Leg Room: 43.0 Inches
Front Track Width: 58.3 Inches
Rear Track Width: 59.0 Inches
Min. Ground Clearance 4.9 Inches

Soft Top Dimensions

1970 Corvette Dimensions - Soft Top

Exterior Dimensions (Soft Top) Interior Dimensions (Soft Top)
Wheelbase: 98.0 Inches Headroom: 38.3 Inches
Overall Length: 182.5 Inches Shoulder Room: 46.9 Inches
Total Body Width: 69.0 Inches Hip Room: 48.8 Inches
Overall Height: 47.9 Inches Leg Room: 43.0 Inches
Front Track Width: 58.7 Inches
Rear Track Width: 59.4 Inches
Min. Ground Clearance 4.9 Inches

Coupe Dimensions

1970 Corvette Dimensions - Coupe

Exterior Dimensions (Coupe) Interior Dimensions (Coupe)
Wheelbase: 98.0 Inches Headroom: 37.2 Inches
Overall Length: 182.1 Inches Shoulder Room: 46.9 Inches
Total Body Width: 69.0 Inches Hip Room: 48.8 Inches
Overall Height: 47.8 Inches Leg Room: 43.0 Inches
Front Track Width: 58.7 Inches
Rear Track Width: 59.4 Inches
Min. Ground Clearance 4.9 Inches

Capacities

Capacities
Passenger Capacity 2 – Driver & Passenger
Curb Weight (lbs) 3,304
– Convertible with soft top
– Convertible; C07 with folding top
– Convertible; C07 less folding top
Coupe
3,290
Interior Passenger Volume (cu. ft)
Interior Trunk Volume (cu. ft) 20
Fuel Capacity (gallons): 4.0 for 350ci. engines (capacity of crankcase less filter – refill)
5.0 for 454ci engines (capacity of crankcase less filter – refill)
Coolant capacity without heater (qts.) 18 for RPO LT1 engine
22 for LS5 engine
Battery: 12 Volt, 62AH for 350ci. engines
12 Volt, 80AH for 454ci. engines

1970 Corvette

1970 Corvette Performance Results

4-Speed Transmission
Standard
L46 LT1 LS5 LS7
Performance weight (lbs.)
3586 3597 3577 3768 3641
Pounds/gross horsepower
11.95 10.28 9.67 9.66 7.91
Pounds/cu.in. piston displacement
10.25 10.28 10.22 8.30 8.02
Gross horsepower/cu.in. displacement
.857 1.00 1.06 8.59
1.01
Power displacement (cu.ft./mile)
262.69 262.69 277.55 312.36 340.75
Displacement factor (cu.ft./mile)
146.51 146.06 155.19 165.79 170.38
0 – 60 mph (seconds)
6.7
Top Speed (mph)
120

1970 Corvette

1970 Corvette Vehicle Identification Numbers (VIN)

VIN Range 194370S400001 – 194370S417316
1 (First Digit) Make/Manufacturer.  1 – Chevrolet
9 (Second Digit) Model series.  9 – Corvette
4 (Third Digit) Engine type.  4 – V8 Engine (all types)
37 (Fourth and Fifth Digits) 37- Corvette Coupe / 67 – Corvette Convertible
0 (Sixth Digit) Model Year.  0 – 1970
S (Seventh Digit) Vehicle Assembly Location. S – St. Louis, Missouri
4XXXXX (Seventh thru Twelfth Digits) Plant Sequence Numbers.
The last six digits begin at 400001 and run thru 417316, accounting for all 17,316 Corvette Coupes/Convertibles built in 1970. Each Vehicle Identification Number (VIN) is unique to an individual car.

1970 Corvette Vehicle Serial Number Plate

For all 1970 Corvettes, the location of the Vehicle Identification Number (VIN) is stamped on a plate attached to the left front body hinge pillar. (See Figure 1 below.)

1970 Corvette Vin Plate Location
1970 Corvette Vin Plate Location

1970 Corvette Body Number & Point Plate

Location:
  • On the driver’s side upper left-hand door hinge pillar.

Example:

1970 Corvette Body Number & Point Plate

  • A01 – Body build date code.
    • A – Designates the Month (See Chart Below).
      • A – Jan., 1970., B – Feb., 1970., C – Mar., 1970., D – Apr., 1970., E – May, 1970., F – Jun., 1970., G – Jul., 1970
      • 01 – Designates the Day of the Month.
  • 400 – Interior Trim code. 400 – Black (Vinyl)
  • 972 – Exterior Color Code. 972 – Classic White

1970 Corvette Engine Identification & Engine Number

  • Location:
    • All engines are stamped on the top front of the right-hand bank of cylinder and case.
  • Engine Identification Example:  V0127CTJ
    • V – Engine build location.
      • T – Tonawanda, NY. (All big block engines.)
      • V – Flint, MI. (All small block engines.)
    • 0127 – Date Code. Month and Day. 0127 – January 27.
    • CTJ – Type Designation. CTJ – 350ci 350hp, 3 or 4 speed manual transmission.
  • Engine Number Example:  70S400001
    • 7 – Model. 7 – Corvette
    • 0 – Model year. 0 – 1970
    • S – Assembly Plant Designation. S – St. Louis
    • 400001 – VIN Sequential Serial Number

1970 Corvette Transmission Identification & Transmission Number

  • Location(s):
    • 3 & 4-Speed Manual (Saginaw) – Stamped on right-hand side of case in the upper forward corner.
    • 4-Speed (Muncie) – Stamped on the top right-hand side of the case.
    • Turbo Hydra-matic Automatic – Name plate tag on right-hand side of case.
  • Transmission Identification Example:
    • POE13A
      • P – Type Designation.
      • P – Muncie
      • 0 – Year. 0 – 1970
      • E13A – Production Month and Date.
        • E – Designates Month (See Chart Below.)
          • A – Jan., B – Feb., C – Mar., D – Apr., E – May, F – June, G – July
          • 13 – Designates Day of the month.
          • A – M20, or B – M21
    • Transmission Number Example:  70S400001
      • 7 – Model. 7 – Corvette
      • 0 – Model year. 0 – 1970
      • S – Assembly Plant Designation. S – St. Louis
      • 400001 – VIN Sequential Serial Number

1970 Corvette

1970 Corvette Factory Options

CODE:
DESCRIPTION:
QUANTITY:
RETAIL PRICE:
19437
Base Corvette Sport Coupe
10,668
$5,192.00
19467
Base Corvette Convertible
6,648
$4,849.00
Custom Interior Trim
3,191
$158.00
A31
Power Windows
4,813
$63.20
A85
Custom Shoulder Belts (std with coupe)
475
$42.15
C07
Auxiliary Hardtop (for convertible)
2,556
$273.85
C08
Vinyl Covering (for auxiliary hardtop)
832
$63.20
C50
Rear Window Defroster
1,281
$36.90
C60
Air Conditioning
6,659
$447.65
G81
Optional rear Axle Ratio
2,862
$12.65
J50
Power Brakes
8,984
$47.40
L46
350ci 350hp Engine
4,910
$158.00
LS5
454ci 390hp Engine
4,473
$289.65
LT1
350ci 370hp Engine
1,287
$447.60
M21
4-Speed Manual Transmission, Close-Ratio
4,383
$0.00
M22
4-Speed Manual Transmission, Close Ratio Heavy Duty
25
$95.00
M40
Turbo-Hydro-matic Automatic Transmission
5,102
$0.00
NA9 California Emissions 1,758 $36.90
N37
Tilt-Telescopic Steering Column
5,803
$84.30
N40 Power Steering 11,907  $105.35
P02
Deluxe Wheel Cover
3,467
$57.95
PT7  White Stripe Tires, F70x15, Nylon 6,589 $31.30
PU9
White Letter Tires, F70x15, Nylon
7,985
$33.15
T60
Heavy Duty Battery (std with LS5)
165 $15.80
UA6 Alarm System 6,727 $31.60
U69
AM-FM Radio
14,529 $172.75
U70
AM-FM Radio, stereo
2,462 $278.10
ZR1
Special Purpose Engine Package
25 $968.95

Base Corvette Convertible (19467)

  • The base price of the 1970 Corvette Convertible without any optional equipment.
  • A 350 cubic inch, 300 horsepower engine, 4-speed wide ratio manual transmission, vinyl interior trim, and a convertible top were included in the base price.
  • The previously optional tinted glass and Positraction axle were also included in the base price.
  • Body design for 1970 was updated with fender flares to reduce wheel-thrown debris damage, which had become a problem with 1968-1969 models.  Exhaust tips were rectangular, replacing the round style of earlier years.  Front grills were square mesh.
  • Parking lamps, located at the grills outer edge, had clear lenses with amber bulbs.

Custom Interior Trim ( — )

  • Optional interior trim upgrade that included a number of custom modifications to the base interior.
  • The custom interior trim included leather seat trim, wood-grain accents and carpet trim on door panels, wood-grain accents on the console, and cut-pile carpeting.
  • All interiors in 1970 were refined, including redesigned seats for additional headroom and easier access to rear storage.

Power Windows (A31)

  • Factory installed power driver and passenger windows.
  • This option was not available to consumers when the RPO ZR1  was ordered.

Custom Shoulder Belts (A85)

  • An addition to the standard lap safety belt that crosses over the shoulder for added safety.
  • The shoulder belts option were included with all Corvette coupes at no additional charge.  The option was also available on the Corvette convertible, but at an additional cost.

Auxiliary Hardtop (for convertibles) (C07)

  • An optional hard-top that could be installed in lieu of the convertible top.

Vinyl Covering (for Auxiliary Hardtop) (C08)

  • This option provided an external vinyl liner application to the auxiliary hardtop.
  • The vinyl covering provided a faux convertible top appearance even when the hardtop was mounted on the car.

Rear Window Defroster (C50)

  • Optional rear window defroster unit.
  • This option was not available to consumers when the RPO ZR1  was ordered.

Air Conditioning (C60)

  • Factory installed air-conditioning.
  • System includes evaporator, blower, condenser, receiver-dehydrator, refrigerant (freon) tank, air intake assembly and duct assembly for both systems.
  • Heater integrated, manually controlled by knobs on instrument control panel that operate bowden cables to activate various doors/ducts and switches to operate system.
  • This option was not available to consumers when the RPO ZR1  was ordered.

Positraction Rear Axle Ratio (G81)

  • The factory optioned rear axles available for the 1970 Corvette.

Power Brakes (J50)

  • Vacuum power assisted brakes; includes dual circuit master cylinder.

350ci, 350hp Engine (L46)

  • Alternate small-block engine with improved 350 horsepower output.

454ci, 390hp Engine (LS5)

  • Alternate big-block engine rated at 390 horsepower and 500 lb/ft of torque.

350ci, 370hp Engine (LT1)

  • Alternate high performance small-block 350 cubic inch engine.
  • It used solid lifters, 11:1 compression, the ‘178’ high-performance camshaft, and a 780 CFM Holley four-barrel carburetor on a special aluminum intake, with rams’ horn exhaust manifolds, Delco transistor ignition and a low-restriction exhaust factory rated at 370 bhp.
  • Redline was 6500 rpm but power fell off significantly past 6200 rpm.

4-Speed Manual Transmission, Close Ratio (M21)

  • A close ratio version of the M20 Muncie 4-speed manual transmission.
  • The gear ratios for the RPO M21 Close Ratio 4-Speed Manual Transmission are: 1st Gear – 2.20:1, 2nd Gear – 1.64:1, 3rd Gear – 1.28:1, 4th Gear – 1.0:1 (Direct).

4-Speed Manual Trans, Close Ratio, Heavy Duty (M22)

  • A heavy-duty version of the Close Ratio Manual Transmission.
  • This heavy duty transmission came equipped with a fine spline input shaft, a larger diameter output shaft and gear teeth that utilized reduced helix angles.  It was equipped with the following gear ratios: 1st Gear – 2.20:1, 2nd Gear – 1.64:1, 3rd Gear – 1.27:1, and 4th Gear – 1.00:1.

Turbo Hydra-Matic Automatic Transmission (M40)

  • An optional, three-speed automatic transmission.
  • The Turbo Hydra-Matic Automatic Transmission consisted of a 3-element hydraulic torque converter and compound planetary gear set.  It was equipped with the following gear ratios: 1st Gear – 2.48:1, 2nd Gear – 1.48:1, and 3rd Gear – 1.00:1.
  • The M40 Turbo Hydra-Matic transmission cost $221.80 when combined with the standard 350 cubic inch, 300 horsepower engine, but cost $290.40 when combined with RPO’s L71, L88 or L89.

California Emissions (NA9)

  • Emissions system designed to meet the more stringent demands of California’s EPA requirements.
  • Only approximately 80 1970 Corvettes were equipped with the California emissions option.

Tilt Telescopic Steering Column (N37)

  • An optional, adjustable steering column and tilt-angle adjustable steering wheel.
  • The Telescopic Steering Column changes the drivers distance from the steering wheel by literally telescoping the steering wheel closer to or further away from the vehicle operator.

Power Steering (N40)

  • Hydraulically assisted power steering.
  • This option was not available to consumers when the RPO ZR1  was ordered.

Deluxe Wheel Covers (P02)

  • Optional deluxe wheel covers.
  • This option was not available to consumers when the RPO ZR1  was ordered.

White Stripe Tires, F70 x 15, nylon (PT7)

  • Standard size tires with a special 3/8″  wide white sidewall stripes.

White Letter Tires, F70x 15, nylon (PU9)

  • Standard size tires with a special 3/8″  wide white sidewall letters.

Heavy Duty Battery (T60)

  • The heavy duty battery provided additional cranking amps to aid in turning the larger LS5 engine.
  • While available as an option on any 1970 Corvette, the Heavy Duty Battery came standard with the LS5 equipped Corvettes.

Alarm System (UA6)

  • A factory installed alarm system.
  • When activated, the alarm system would trigger the horn to sound in a repetitive pattern of short bursts.
  • This option was not available to consumers when the RPO ZR1  was ordered.

AM-FM Radio (U69)

  • A standard/stock dealer installed Corvette radio for model years 1968-1971.
  • The radio broadcast only a mono signal.
  • This option was not available to consumers when the RPO ZR1  was ordered.

AM-FM Radio, Stereo (U79)

  • An optional dealer installed Corvette radio for model years 1968-1971.
  • This radio option provided a true stereo signal.
  • This radio featured green lettering.
  • This option was not available to consumers when the RPO ZR1  was ordered.

Special Purpose Engine Package (ZR1)

  • Optional performance and handling upgrade.
  • The ZR1 option included the LT1 engine, M22 transmission, heavy-duty power brakes, transistor ignition, special aluminum radiator, and special springs, shocks, and front & rear stabilizer bars.
  • When the ZR1 option was ordered, the following options were not available on the 1970 Corvette: Power Windows (A31), Rear
  • Window Defroster (C50), Air Conditioning (C60), Power Steering (N40), Deluxe Wheel Covers (P02), Alarm System (UA6), AM
  • FM Radio (U69), AM-FM Radio, stereo (U79).
  • ZR1’s came equipped with metal fan shrouds.

NOTES:

  • An LS7 engine rated at 460 horsepower (or 465 horsepower) was planned to be included as an option, and GM went as far as to list it in the vehicle order guides.  The LS7 was to be a big-block version of the LT1, including aluminum heads.  A ZR2 package with the LS7 was also planned.  The suffix for the LS7 was assigned as CZL for manual, CZN for automatic.  The LS7 and ZR2 were canceled and it is believed that none were delivered to retail customers.
  • Big block engine displacement increased from 427 cubic inches to 454 cubic inches.  The small block engine displacement remained the same at 350 cubic inches, although the new LT1 engine option included solid lifters and was rated at 370 horsepower.
  • The 1970 model year included the lowest production numbers of any Corvette since 1962, due in part to an extended production run of the 1969 model year.

See Also

C3 1968
1969
1970
1971
1972
1973 1974 1975
1976 1977 1978 1979 1980 1981 1982
Gen C1 C2 C3 C4 C5 C6 C7

1970 Corvette

1970 Corvette Recalls

Recall: 1
Make:
CHEVROLET
Model: CORVETTE
Model Year: 1970
Manufacturer: CARDONE INDUSTRIES, INC.
Mfr’s Report Date: MAY 07, 2003
NHTSA CAMPAIGN ID Number: 03E032000
NHTSA Action Number: N/A
Component: SERVICE BRAKES, AIR:DISC:CALIPER
Potential Number of Units Affected: 15,899

Summary:

REMANUFACTURED REAR BRAKE CALIPERS, PART NOS. 18-7019, 18-7020, 16-7019, AND 16-7020, MANUFACTURED FROM FEBRUARY 1, 2002, TO APRIL, 25, 2003., AND FOR USE ON 1965 THRU 1982 CHEVROLET CORVETTES. THE SUBJECT BRAKE CALIPERS WERE MANUFACTURED USING IMPROPERLY MANUFACTURED PISTON SEALS. THESE SEALS ARE INTENDED TO PREVENT FLUID LEAKAGE BETWEEN THE CALIPER HOUSING AND THE PISTONS. THESE BRAKE CALIPERS ARE FOR USE ONLY ON 1965 THRU 1982 CHEVROLET CORVETTE VEHICLES. THIS RECALL DOES NOT INVOLVE GENERAL MOTORS CORPORATION OR ANY OF ITS PRODUCTS.

Consequence:

UNDER THESE CONDITIONS, THE VEHICLE OPERATOR MAY NOT BE ABLE TO STOP THE CAR, POSSIBLY RESULTING IN A VEHICLE CRASH.

Remedy:

CARDONE WILL NOTIFY ITS CUSTOMERS AND ALL UNSOLD INVENTORY WILL BE REPURCHASED AND WILL PROVIDE A FULL REFUND TO CUSTOMERS. OWNER NOTIFICATION IS EXPECTED TO BEGIN DURING MAY 2003. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT CARDONE AT 215-912-3000.

Notes:

ALSO, CUSTOMERS CAN CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION’S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).


1970 Corvette Service Bulletins

None.


1970 Corvette Common Issues

The following list of common issues is intended for individual reference only, and may not reflect the specific issues of every 1970 Corvette.  This information comes from a variety of sources including the NHTSA Defects Reports pages.  While the intent of this page is to identify the common issues pertaining to the 1970 Corvette, it is not an all-inclusive list and should be used for reference only.

1970 Corvette Mechanical Issues

ENGINE (GENERAL)

One of the common issues with the engines in a 1970 Corvette have nothing to do with any specific mechanical issues.  The issue is that, more often than not, the original engine has been replaced, and the replacement engine is not the same type/model as was installed when the car was originally manufactured.
Overheating is a common problem on early C3 Corvettes.  One of the most common causes of overheating is the replacement of the stock radiator fan and fan shroud with an electric fan.

CRANKCASE VENTILATION/PCV VALVE

PCV (Positive Crankcase Ventilation) Valves are important to proper engine operation.  The PCV valve allows a pressure drop (vacuum) in the engine’s crankcase.  In turn, this helps the engine piston rings seal against the cylinder wall.  The PCV valve also acts as a check valve under hard acceleration when engine vacuum is zero. This allows the crankcase ventilation tube that is connected to the air cleaner to draw a vacuum in the crankcase when the throttle is wide open.

PCV valves are often neglected but they play an important role in engine drivability and engine life. An improperly operating/damaged PCV valve can cause hesitation, poor idling, and stalling.  The crankcase should never be totally closed- it will cause extreme oil usage and oil leaks  Be cautious of replacing crankcase/valve covers with aftermarket brands that do not include baffles for the PCV Valve or crankcase tubes.  Also, make sure that all PCV grommets are properly sealing to ensure that the proper pressures are maintained and that oil blow-by does not occur.

TRANSMISSION

One of the common issues with the transmissions in a 1970 Corvette have nothing to do with mechanical issues.  The issue is that, more often than not, the original transmission has been replaced, and the replacement transmission is not the same type/model as was originally installed when the car was manufactured.

The transmission vacuum modulator that controls shift timing could have a broken diaphragm allowing transmission fluid to be drawn into the engine. A minor vacuum modulator diaphragm leak will foul the number eight plug slowly and result in a minor loss of transmission fluid. A severe vacuum modulator diaphragm leak will create smoke out the tailpipe and noticeable transmission fluid loss. The number eight cylinder intake manifold runner is where the vacuum supply to the automatic transmission modulator is located. This number eight intake manifold runner also supplies the headlamp actuator system. Therefore, this vacuum supply can create a very rough idle if both systems were leaking.  Many times the fitting that screws into the intake manifold is loose.

POWER WINDOWS

Both the driver and passenger door windows are known to fail.  There are generally two conditions which cause the window to stop operating: 1.) A blown fuse or defective relay, or, 2.) A failed power window motor.  When inspecting the vehicle for a cause, always check the fuse first.  The replacement of a power window motor is a time consuming process requiring access to the inner workings of the door via removal of the inner door panel.

In instances where the window fails to go up completely, inspect the window gear regulator.  If any of the gear teeth are missing from the widow regulator, the gear will need to be replaced.  If the teeth on the regulator gear are not damaged, the window motor will need to be removed from the regulator and inspected. A damaged worm gear (gear drive on the window motor) will require replacement of the entire window motor.

If the window rattles when the vehicle door is closed, inspect both the window regulator mounting bracket (which may be damaged/broken), and the window anti-rattle cushions.  Due to age, the window cushions can become damaged or may fall off the vehicle.  Fortunately they can be easily replaced at many auto parts stores.
If the window travels excessively fast during operation, inspect the power window spring.  A broken spring can result in costly repairs to the to the power window motor or the window regulator gear.

1970 Corvette Electrical Issues

TAILLIGHTS

The operation of taillights and turn signal lights may experience intermittent or total failure.  Although there are a number of possible causes for this issue, the most common cause of failure is a bad ground in the taillight circuit.  When troubleshooting, check for breaks in wiring and check for wiring grounds.  Other possible causes for failure include bad lightbulbs, bad turn signal switch,  and/or bad brakelight switch.

EXTERIOR ISSUES

BODY/FRAME

Depending on the climate and driving conditions, the 1970 Corvette is known to develop extensive corrosion/rust in a number of areas including the frame and the “bird cage”.  On the frame, the most common areas where rust is known to develop include just forward of the rear wheels, the front cross member, the framework around the doors and the windshield pillars (the area known as the aforementioned “bird cage.”)  One of the tell-tale signs of a rust/corrosion issue is the presence of dampness/wetness on the forward floor areas.  Severe corrosion may also resort in door sag and can adversely affect door alignment, resulting in a large (and increasing) gap between the top of  the door and the fender.

HEADLAMP ACTUATOR VACUUM LEAKS

All Corvettes from 1968-1981 can have a large vacuum leak from the headlight actuator vacuum system that will affect the engine idle.  When experiencing rough idle, remove the vacuum hose and plug the fitting temporarily, then check engine performance.  See Transmission Modulator Vacuum Leaks above for additional information.
The rubber hoses and other components of the headlight vacuum system are known to wear out.   In many instances, only one of the headlight assemblies will operate.  Always check all rubber vacuum lines when even a single headlight assembly is not operating properly as many times, it the result of a failed or collapsed line.

DOOR HINGES

Over time, the door hinges on all C3 Corvettes fatigue and begin to fail, causing the doors to sag and other alignment issues including broken door seals, water leaks, and road noise.  To prolong the hinge life, lubricate the hinges regularly.  In the event that the hinges do sag, replacing the hinge bushings and pin is also an option, although replacing the upper hinge pin will require the removal of the dashboard speedometer cluster.
1970 Corvette

1970 Corvette Maintenance Schedule

Maintenance Schedule

The time or mileage intervals indicated on this website are intended as a guide for establishing regular maintenance and lubrication periods.  Sustained heavy duty or high speed driving, or driving under adverse conditions may require more frequent servicing.

1970 Corvette Maintenance Schedule
1970 Corvette Maintenance Schedule

Additional Maintenance and Lubrication

In addition to the items listed above, it is also recommended that the following items are inspected every 300 miles or 2 weeks, whichever comes first:

  • Check Tire Pressure
  • Check Battery Water Level
  • Check Oil Level In Engine

Compression Test

Remove air cleaner and block throttle and choke in wide open position.  Hook up starter remote control cable and insert compression gauge firmly in spark plug port.  Whenever the engine is cranked remotely at the starter, with a jumper cable or other means, the distributor primary lead must be disconnected from the negative post on the coil and the ignition switch must be in the “ON” position.  Failure to do this will result in a damaged grounding circuit in the ignition switch.

Crank engine through at least four compression strokes to obtain highest possible reading. Check and record compression of each cylinder.  If one or more cylinders reads low or uneven, inject about a tablespoon of engine oil on top of pistons in low reading cylinders (through spark plug port.)  Crank engine several times and recheck compression.   If compression comes up but does not necessarily reach normal, rings are worn.  If compression does not improve, valves are burnt, sticking or not sealing properly.  If two adjacent cylinders indicate low compression, the cause may be a head gasket leak between the cylinders.  Engine coolant and/or oil in cylinders could result from this defect.

Carburetor Adjustments

The adjustments described apply to all carburetors used, except as noted.  All adjustments are made with the engine at normal operating temperature.

Idle Speed and Mixture(1966-1970)

Remove distributor vacuum line at distributor and plug hose.  Start engine and set the throttle stop screw for recommended idle speed.  The choke valve must be wide open and the fast idle inoperative.  Adjust one idle mixture screw at a time for smoothest, fastest idle speed.  On A.I.R. cars, turn one adjusting screw at a time until engine speed drops approximately 30 rpm and starts to roll (lean mixture), then turn screw out exactly 1/4 turn for final setting.  Readjust throttle stop screw for recommended idle speed.  Basic setting for idle mixture screws is 2 turns open from fully closed for 1966-68, 3 turns for 1969, 1 turn for Holley 2300, Air condition to be ON, except Mark IV and all 1972.
When adjusting the idle speed be sure that the idle compensator is closed.  Close it manually if necessary.  After idle speed is adjusted, check by pressing down on the compensator.  If speed drops, readjust idle speed. NOTE: Idle speed adjustments on cars with automatic transmissions must be made with transmission in Drive and idle stator switch, if so equipped, closed.  Be sure parking brake is on.

Idle Speed and Mixture – Holley 2300

All adjustments are same as previously described except as follows: On models equipped with idle stop solenoid, adjust idle stop solenoid screw to give 1000 rpm, then adjust idle mixture adjusting screw to specified rpm.  Turn idle mixture screw in (leaner mixture) until engine speed drops 20 rpm, then turn out 1/4 turn.  Disconnect lead at idle stop solenoid (throttle level will rest against regular stopscrew.)  Adjust this stopscrew for idle speed of 500 rpm.  Do not change setting of idle stop solenoid stopscrew or idle mixture screw.

Fast Idle (1966-1976)

With the transmission  in neutral, position the cam follower on the high step (2nd step, 1971-1972) of the fast idle cam.  Adjust fast idle screw of Rochester carburetors to obtain recommended fast idle speed.  Bend fast idle lever on Holleys.  On 1970-72 models, disconnect transmission controlled spark solenoid.

Dashpot Adjustment

With slow idle speed correctly adjusted, fully open choke and make sure fast idle cam follower is off steps of cam.  With dashpot fully compressed, adjust for 1/16″ clearance between dashpot plunger and throttle lever.

Automatic Choke

Remove the air cleaner and check to see that choke valve and rod more freely.  Disconnect choke rod at choke lever.  Check choke adjustment by holding choke valve closed and position rod so that it contacts stop.  If necessary, adjust rod length by bending rod at offset.  Bend must be such that rod enters choke lever hole freely and squarely.  Connect rod at choke lever and install air cleaner.

Air Injection Reactor (A.I.R.)

Description and Operation

The A.I.R. system is used to burn the unburned portion of the exhaust gases to reduce its hydrocarbon and carbon monoxide content.  The system forces compressed air into the exhaust manifold where it mixes with the hot exhaust gases. The hot exhaust gases contain unburned particles that complete their combustion when the addition air is supplied.

The system consists of: An air pump, diverter valve, check valve(s), AIR pipe assemblies and connecting hoses and fittings.  Carburetors and distributors for AIR engines are made to be used with the system and should not be replaced with components intended for use with engines that do not have the system.

The air pump is a two-vane pump which compresses fresh filtered air and injects it into the exhaust manifold.  The pump consists of: a housing, centrifugal filter, set of vanes that rotate about the centerline of pump housing bore, the rotor, and the seals for the vanes.  The centrifugal filter is replaced by first removing the drive belt and pump pulley; then pulling filter off with pliers.  Care should be taken to prevent fragments from entering the air intake hole.  NOTE: A new filter may squeal when first put into operation.  Additionally, GREAT CARE should be taken in working on the compressor as the aluminum used is quite soft and thin.  The air pump is operating satisfactorily when the air flow from it increases as engine speed increases.

The air hoses should be replaced only with hoses which are designed for AIR system use, as no other type hoses can withstand the high temperature.

Check and Adjust Dwell

Start engine then check ignition dwell.  With engine running at idle, raise the adjustment screw window and insert an Allen wrench in the socket of the adjusting screw.  Turn the adjusting screw as required until a dwell reading of thirty degrees is obtained.  A two degree variation is allowable for wear.  Close access cover fully to prevent the entry of dirt into the distributor.  If a dwell meter is not available, turn adjusting screw clockwise until engine starts to misfire, then turn screw one-half turn in the opposite direction to complete adjustment.

Slowly accelerate engine to 1500 rpm and note dwell reading.  Return engine to idle and note dwell reading.  If dwell variation exceeds specifications, check for worn distributor shaft, worn distributor shaft bushing or loose breaker plate.

Ignition System

Remove distributor cap, clean cap and inspect for cracks, carbon tracks and burned or corroded terminals.  Replace cap where necessary.   Clean rotor and inspect for damage or deterioration.  Replace rotor where necessary.  Replace brittle, oil soaked or damaged spark plug wires.  Install all wires to proper spark plug.  Proper positioning of spark plug wires in supports is important to prevent cross-firing.  Tighten all ignition system connections.  Replace or repair any wires that are frayed, loose or damaged.

Ignition Timing

Disconnect the distributor spark advance hose and plug the vacuum source opening.  Start engine and run at idle speed.  Aim timing light at timing tab.  The markings on the tabs are in two degree increments (the greatest number of markings on the “A” side of the “Q”). The “O” marking is TDC (Top Dead Center) and the BTDC settings fall on the “A” (advance) side of the “O”.  Adjust the timing by loosening the distributor clamp and rotating the distributor body as required, then tighten the clamp, and recheck timing.  Stop engine and remove timing light and reconnect the spark advance hose.

Spark Plugs

Inspect each plug individually for badly worn electrodes, glazed, broken or blistered porcelains and replace plugs where necessary.  Clean serviceable spark plugs thoroughly, using an abrasive-type cleaner such as sand blast.  File the center electrode flat.  Inspect each spark plug for make and heat range.  All plugs must be of the same make and number.  Adjust spark plug gaps to .035 in. using a round feeler gauge.  If available, test plugs with a spark plug tester.  Inspect spark plug hole threads and clean before installing plugs.  Install spark plugs with new gaskets and torque to specifications.  Connect spark plug wiring.

Transistorized Distributor (H.E.I. System)

There are no moving parts in the ignition pulse amplifier, and the distributor shaft and bushings have permanent type lubrication, therefore no periodic maintenance is required for the magnetic pulse ignition system.

Distributor (Breaker Point System)

Check the distributor centrifugal advance mechanisms by turning the distributor rotor in a clockwise direction as far as possible, then releasing the rotor to see if the springs return it to its retarded position.  If the rotor does not return readily, the distributor must be disassembled and the cause of the trouble corrected.

Check to see that the vacuum spark control operates freely by turning the movable breaker plate counter-clockwise to see if the spring returns to its retarded position.  Any stiffness in the operation of the spark control will affect the ignition timing.  Correct any interference or binding condition noted.

Examine distributor points and clean or replace if necessary.  Contact points with an overall gray color and only slight roughness or pitting need not be replaced.  Dirty points should be cleaned with a clean point file.  Use only a few strokes of a clean, fine-cut contact file.  The file should not be used on other metals and should not be allowed to become greasy or dirty.  Never use emery cloth or sandpaper to clean contact points since particles will embed and cause arcing and rapid burning of points.  Do not attempt to remove all roughness nor dress the point surfaces down smooth.  Merely remove scale or dirt.  Clean cam lobe with cleaning solvent, and rotate cam lubricator wick end (or one-hundred-eighty degrees as applicable).  Replace points that are burned or badly pitted.

Where prematurely burned or badly pitted points are encountered, the ignition system and engine should be checked to determine the cause of trouble so that it can be eliminated.  Unless the condition causing point burning or pitting is corrected, new points will provide no better service than the old points.

Check point alignment then adjust distributor contact point gap to .019″ (new points) or .016″ (used points).  Breaker arm rubbing block must be on high point of lobe during adjustment.  If contact points have been in service, they should be cleaned with a point file before adjusting with a feeler gauge.

Check distributor point spring tension (contact point pressure) with a spring gauge hooked to breaker lever at the contact and pull exerted at 90 degrees to the breaker lever.   The points should be closed (cam follower between lobes) and the reading taken just as the points separate.  Spring tension should be 19-23 ounces.  If not within limits, replace.  Excessive point pressure will cause excessive wear on the points, cam and rubber block.  Weak point pressure permits bouncing or chattering, resulting in arcing and burning of the points and an ignition miss at high speed.

Install rotor and distributor cap.  Press all wires firmly into cap towers.

Battery and Battery Cables

The top of the battery should be clean and the battery hold-down properly tightened.  Particular care should be taken to see that the top of the battery is kept clean of acid film and dirt.  When cleaning batteries, wash first with a dilute ammonia based or soda solution to neutralize any acid present and then flush off with clean water.  Keep vent plugs tight so that the neutralizing solution does not enter the cell.  The hold-down bolts should be kept tight enough to prevent the batter from shaking around in its holder, but they should onto be tightened to the point where the battery case will be placed under a severe strain.
To ensure good contact, the battery cables should be tight on the battery posts.  Oil battery terminal felt washer.  If the battery posts or cable terminals are corroded, the cables should be cleaned separately with a soda solution and wire brush.  After cleaning and before installing clamps, apply a thin coating of a petrolatum to the posts and cable clamps to help slow corrosion.
If the battery has remain undercharged, check for loose or defective fan belt, defective alternator, high resistance in the charging circuit, oxidized regulator contact points, or a low voltage setting.  If the battery has been using too much water, the voltage output is too high.

Crankcase Ventilation

Inspect for deteriorated or plugged hoses.  Inspect all hose connections.  On engines with closed element air cleaners, inspect crankcase ventilation filter and replace if necessary.  On engines with open element air cleaners, remove flame arrestor and wash in solvent then dry with compressed air.

Brakes

Check the brake fluid regularly, for as the brake pads wear the level will drop rapidly.  It should be replenished only with the recommended fluid.  Check disc brake assemblies to see if they are wet; it would indicate a leaking cylinder.
Disc brakes do not need periodic adjustments; they are self adjusting.   The pads should be replaced when the friction material gets down to 1/16″.  This is when the groove in the center of the pad is gone.  Check by removing wheel and looking directly into caliper.

Clutch Pedal Play

Check clutch action by holding pedal 1/2″ from floor and move shift lever between first and reverse several times, with engine running.  If shift is not smooth adjust clutch.  Free play with pedal released is approx. 1-1/4″ to 2″ and 2″ to 2-1/2″ for heavy duty.

Clutch Adjustment

At clutch lever near firewall remove clutch return spring.  To decrease clutch pedal free play remove clutch pedal return spring and loosen lower nut on clutch pedal rod; take up play with upper nut.  Continue until proper play is obtained, then securely tighten top nut and replace spring.  To increase pedal play work nuts in opposite sequence.

Accelerator Linkage

Disconnect control linkage at carburetor throttle lever.   Hold carburetor throttle lever in wide position.  Pull control linkage to wide open position.  (On vehicles equipped with automatic transmission, pull through detent.)  Adjust control linkage to freely enter hole in carburetor throttle lever.  Connect control linkage at throttle lever.

Throttle Linkage Adjustment (Powerglide)

Remove air cleaner, disconnect accelerator linkage at carburetor.  Disconnect accelerator return and trans. road return springs.  Pull upper rod forward until transmission is through detent.  Open carburetor wide open, at which point ball stud must contact end of slot in upper rod.  Adjust swivel on end of rod if necessary.

Throttle Linkage Adjustment (Turbo Hydra-matic 350)

Disengage the snap lock and position the carburetor to wide open throttle.  Push the snap lock downward until the top is flush with the rest of the cable.

Throttle Linkage Adjustment (Turbo Hydra-matic 400)

Pull detent switch driver to rear until hole in switch body lines up with hole in driver.  Insert a 3/16″ pin through hole to depth of 1/8″, and loosen mounting bolts.  Open throttle fully and move switch forward until lever touches accelerator lever.  Tighten mounting bolt and remove pin.

EGR Valve Check

A rough idling engine may be caused by a malfunction of the valve.  Check by pinching vacuum hose to carburetor with engine idling.  If idling smooths out, the valve should be removed for cleaning or replacement if something appears to be broken.

Lubrication

Engine Oil

The car should be standing on level ground and the oil level checked with the dipstick.  Withdraw the dipstick, wipe it with a clean rag, replace and withdraw again.   The mark made by the oil on the lower end of the dipstick will indicate the oil level.  If necessary, oil should be added through the filler cap.  Never let the oil level fall so low that it does not show at all on the dipstick.  If in doubt, it is better to have a bit too much oil than too little.  Never mix oils of different brands, the additives may not be compatible.

Engine Oil Drain and Replacement

Place a pan under the oil pan drain plug and remove plug.  Be sure pan is of a large enough capacity to hold the oil.  Move pan under filter and remove filter by turning if counterclockwise.   Clean gasket surface of cylinder block.  Coat gasket of new filter with engine oil.   Thread filter into adapter.  Tighten securely by hand.  Do not overtighten filter.  Remove drop pan.
Remove drain pan.  Inspect oil pan drain plug gasket and replace if broken, cracked, or distorted.  Install drain plug and tighten.  Fill crankcase to required level with recommended oil.  Operate engine at fast idle and check for oil leakage.
Crankcase Capacities: 327 & 350 Engines – 4 quarts, 427 & 454 Engines – 5 quarts.
When changing oil filter, add one additional quart.

Transmission, Automatic

Check fluid level with engine idling, transmission in neutral and engine at normal operating temperature.  Add fluid as needed to bring level to mark.  Do not overfill.

Every 12,000 miles or sooner, depending on service, remove fluid from sump and add new fluid.  Operate transmission and check fluid level.  Every 24,000 miles the transmission sump strainer of the Turbo Hydra-Matic transmission should be replaced.
Refill Capacity: Powerglide – 2 quarts, Turbo Hydra-Matic – 7-1/2 quarts.

Transmission, Manual

Raise car on lift, clean dirt and grease from area around the filler plug.  Plug is located on side of transmission case.  Remove plug and place finger tip inside hole.  The oil should be just about level with the bottom edge of the hole.  Add oil as needed, using a plastic syringe.

Distributor

Change cam lubricator end for end at 12,000 mile intervals.  Replace at 24,000 mile intervals.

Differential

With the car standing level, clean dirt and grease from area around filler plug.  Remove plug and place finger tip inside hole.  The oil should be just about level with the bottom edge of the hole.  Add oil, with a plastic syringe, as needed.

See Also

C3 1968
1969
1970
1971
1972
1973 1974 1975
1976 1977 1978 1979 1980 1981 1982
Gen C1 C2 C3 C4 C5 C6 C7

Source Material:

  1. CORVETTE: America’s Star-Spangled Sports Car, The Complete History – Copyright 1973, Automobile Quarterly
  2. The Pocket Book of the Corvette: The Definitive Guide to the All American Sports Car – Copyright 2003, Barnes & Noble
  3. CORVETTE: Sports Car Superstar – Copyright 2005, PIL – Publications International, Ltd.
  4. Corvette Black Book – Copyright 2009, Michael Bruce Associates, Inc.
  5. The Complete Book of Corvette – Every Model Since 1963 – Copyright 2006, MBI Publishing

No Comment

Leave a reply

Your email address will not be published. Required fields are marked *