By the late 1970’s, Corvette production was moving at a pace that had never been seen in the history of the car. As Chevrolet General Manager, Robert Lund, had stated in March, 1977, “The St. Louis Plant is operating two nine-hour shifts daily and working overtime two Saturdays a month just to meet sales demand. Current demand is running more than 29 percent ahead of last year.” Little did anyone realize that, after the popularity of the 1978 Pace Car and Silver Anniversary Editions in 1978, Corvette was about to set another production record – manufacturing more than 50,000 Corvettes in one year – with the 1979 model year. At the same time, Corvette was about to surpass another record – a base sales price of more than $10,000 – for the first time in the car’s history.
The price increase in the 1979 model year was well justified, especially given that the Corvette had been fast approaching that cost threshold for the past couple of years.
As before, Chevrolet engineers had continued adding more of the previously optional features available to consumers to the standard base package.
While in 1978, tilt-telescopic steering columns, air conditioning, and power windows had all been optional, nearly 80 percent of all the cars sold that year included all three of these options – which, when added up, cost consumers an additional $910.00 over the base price of $9,351.89. In early 1979, while these items remained optional for a time (now at a combined cost of $966.00,) it was that this trio of optional equipment become a standard part of the car.
On May 7, 1979, they officially became part of the standard equipment group, and Corvette’s base price climbed to $10,220.23. By the end of the production year, the base price would soar even higher as additional options – along with a strong inflationary spiral on the cost of some of the standard equipment – pushed the car’s base price north of $12,000.00.
While the fastback Corvette design introduced in 1978 carried over into the 1979 model year, there were a few, mostly subtle, refinements made to the car’s overall appearance. For one, the “25th Anniversary” emblems were replaced by the more traditional “crossed flags” which had been a key identifier of the Chevy Corvette for more than a quarter century.
Additionally, the chrome trim that wrapped the 1978 rear window and the roof panels was replaced with black trim moldings. Tungsten-halogen headlights were phased into 1979 production early in the model year for increased visibility. The tungsten-halogen headlight beams replaced only the high-beam units. Lastly, a couple of items the 1978 Pace Car Package became options for the 1979 model year.
Tinted roof panels (RPO CC1) became available to consumers, as did the front and rear spoilers (RPO D80). The spoilers were functional, decreasing drag by about 15% and increasing fuel economy by about a half-mile per gallon.
Despite this, sales of Corvettes with this option in 1979 accounted for just under 13% of total sales that year.
Moving inward, the interior received slightly more refinement than the exterior. The biggest, most notable change centered around the introduction of the new “high back” seat style previously introduced on the 1978 Pace Car Replicas. These same seats were now standard equipment for the 1979 model year. The seats used an extensive amount of plastic in their frame structure which resulted in an overall weight reduction of about twelve pounds per seat.
DID YOU KNOW: The 1979 Corvette was the first model year to offer an AM/FM Radio as standard equipment. Prior to 1979, if a Corvette owner wanted to include a radio, they ordered it at an additional cost to the base price.
At the same time, the new seats offered improved side bolster support to its occupants. They also featured seat backs that folded at a higher point (than most conventional seats) to permit easier rear storage area access.
Inertia introduced which restrained the seat backs during sudden deceleration, which negated the need for manual locks on these new, folding seats. Despite all this, the new seats did not offer reclining seatbacks, which were becoming increasingly available in most vehicles – even the cheapest Japanese cars being built that year.
While the seats received a great deal of attention, the rest of the interior was subject to a number of other small changes as well. The driver and passenger seat tracks were redesigned to provide an additional inch of forward travel.
The ignition cylinder lock received additional shielding to reinforce it, making it more difficult to access in the event of an attempted car theft. The previously optional AM-FM radio became standard equipment, while an illuminated visor-mirror combination for the passenger sunvisor became an available option on the 1979 Corvette. An 85 miles-per-hour (max.) speedometer, which would be officially introduced as standard equipment in the 1980 Corvette, was installed on some late-production 1979 models. This last was the result of a Federal mandate that was slated to begin in September, 1979 and would remain in effect until March, 1982.
Mechanically, both the base L48 and optional L82 engines received a 5 horsepower increase due to a new “open flow” muffler design. Additionally, the low restriction, dual snorkel air intake that had been introduced on the L82 engine was added to the L48 engine, which gave the base engine an additional 5 horsepower boost, resulting in an overall output of 195hp for the L48 and 225hp for the optional L82 engines, respectively.
Elsewhere on the car, shock absorber rates were standardized so that they were the same, regardless of the type of transmission (manual or automatic) installed. On cars equipped with an automatic transmission, the final drive ratio was lowered from 3.08:1 to 3.55:1. The fuel filler pipe was redesigned to make it more difficult for consumers to modify for leaded-fuel access.
In total, Chevrolet manufactured 53,807 Corvettes in 1979, which set the record for the most Corvettes built in a single year of the car’s 26 year history (and a record which remains even today!)
It was the height of the Corvette’s acceptance, which was ironic given that General Motors had once been convinced that the C3 model would never sell half as well. Instead, the car’s popularity was stronger than ever, despite an increasing number of competitors vying for consumer attention. It had proven to be indispensable as both a high-profit personal car as well as a showroom sweetheart.
Automotive reviewers and critics remained skeptical of the car’s value given its steadily rising prices and the availability of comparatively priced sports cars like the Mazda RX-7 (with base pricing starting at just $6,395), the Datsun 280ZX ($9,899.00), and even the 1979 Porsche 924 ($12,025.00).
Still, none could argue that the Corvette was still an impressive straight-line contender in this field of European and Asian imports. Road & Track Magazine test drove a 1979 Corvette equipped with an L82 engine and recorded a 0-60 time of just 6.6 seconds, a standing quarter-mile time of 15.3 seconds at 95 mph, and a top speed of 127 mph.
Still, most critics agreed that the C3 was again getting “long in the tooth” and, while the prestige of owning a Corvette continued to flourish amongst consumers, serious automobile enthusiasts were beginning to question how much longer it would be before Chevrolet introduced the “next generation” of the beloved sports car.
With more than a half decade to go before the actual arrival of the C4, the speculation would continue, though the engineers behind Corvette still had a few tricks up their sleeves, as would be seen in the coming years as the production of the third-generation “Shark” started to draw to a close.
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):
1Z8789S400001 – 1Z8789S453807 (coupe)
ZAA: 350 CUBIC INCH, 195 HORSEPOWER, MANUAL, EARLY PRODUCTION
ZAB: 350 CUBIC INCH, 195 HORSEPOWER, AUTOMATIC, EARLY PRODUCTION
ZAC: 350 CUBIC INCH, 195 HORSEPOWER, AUTOMATIC, CALIF. EMISSIONS, EARLY PRODUCTION
ZAD: 350 CUBIC INCH, 195 HORSEPOWER, AUTOMATIC, HIGH ALTITUDE
ZAF: 350 CUBIC INCH, 195 HORSEPOWER, MANUAL
ZAH: 350 CUBIC INCH, 195 HORSEPOWER, AUTOMATIC
ZAJ: 350 CUBIC INCH, 195 HORSEPOWER, AUTOMATIC, CALIFORNIA EMISSIONS
ZBA: 350 CUBIC INCH, 225 HORSEPOWER, MANUAL
ZBB: 350 CUBIC INCH, 225 HORSEPOWER, AUTOMATIC
All welded, full length, ladder constructed frame with five (5) cross-members. Side rails and intermediate cross-members box section; front crossmember box girder section. Eight (8) body mounting points.
Independent, SLA type, coil springs with center mounted shock absorbers, spherical joint steering knuckle pivots.
Wheel Travel (Design):
Wheel to spring, travel ratio:
Reinforced steel stamping with pre-loaded steel encased rubber bushings at pivot
Direct, double acting, hydraulic
– Piston Diameter:
– Bushing Material:
Front Wheel Alignment (Curb)
– Camber (degrees):
P0.709 +/- 1/2
– Caster (degrees):
P2.405 +/- 1/2
– Toe-in (total):
0 +/- 1.32
– Steering Axis Inclination (degrees):
7.683 @ 5° camber
Rear Axle & Rear Suspension
Fixed differential housing hypoid ring and pinion gear set, tubular articulating inner axle shafts and short solid outer shafts with integral drive flange, independently sprung rear wheels.
Full independent with frame-anchored differential. Position of each wheel established by 3 links; tubular axle drive shafts, transverse strut rods,and torque control arms. Vertical suspension loads taken by transverse leaf spring. Built-in camber adjustment at strut rod inner ends.
Vehicle Assembly Location. S – St. Louis, Missouri
4XXXXX (Eighth thru Thirteenth Digits)
Plant Sequence Numbers.
The last six digits for the Corvette Coupe begin at 400001 and run thru 453807, accounting for all 53,807 Corvette Coupes built in 1979. 5,227 Corvettes were sold in Canada. Each Vehicle Identification Number (VIN) is unique to an individual car.
1979 Corvette Vehicle Serial Number Plate
For all 1979 Corvettes, the location of the Vehicle Identification Number (VIN) is stamped on a plate attached to the left front body hinge pillar.
1979 Corvette Body Number & Point Plate
On the driver’s side upper left-hand door hinge pillar.
A01 – Body build date code.
A – Designates the Month (See Chart Below).
A – Aug., 1978B – Sep., 1978C – Oct., 1978D – Nov., 1978E – Dec., 1978F – Jan., 1979, G – Feb., 1979H – Mar., 1979 I – Apr., 1979 J – May, 1979 K – Jun., 1979 L – Jul., 1979, M – Aug., 1979N – Sep., 1979
01 – Designates the Day of the Month.
592 – Interior Trim code. 592 – Light Beige (Leather)
10 – Exterior Color Code Upper. 10 – Classic White
1979 Corvette Engine Identification
All engines are stamped on the top front of the right-hand bank of cylinder and case.
Engine Identification Example:
F – Source Designation.
F – Flint, MI
1210 – Date Code. Month and Day. 1210 – December 10.
4-Speed (Muncie) – Stamped on the top right side of the case at adapter.
3-Speed Automatic – Name plate tag on right-hand side of case above filler plug.
Transmission Identification Example:
SS – Type Designation.
SS – 4-Speed Manual
6TB – 3-Speed Automatic
R – Source Designation.
R – Muncie
Y – Toledo
9 – Year. 9 – 1979
E01D – Production Month and Date.
E – Designates Month (See Chart Below.)
A – Jan. / B – Feb. / C – Mar. / D – Apr. / E – May / H – June / K – July / M – Aug. / P – Sept. / R – Oct. / S – Nov. / T – Dec.
01 – Designates Day of the month.
D or N – Designates Day or Night Shift on Automatic only.
1979 Corvette Factory Options
Base Corvette Sport Coupe
Power Door Locks
Removable Glass Roof Panels
Rear Window Defogger
Spoilers, Front and Rear
Heavy Duty Shock Absorbers
Optional Rear Axle Ratios
350ci, 225hp Engine
4-Speed Manual Trans, Close Ratio
High-Altitude Emission Equipment
Tilt-Telescopic Steering Column
Aluminum Wheels (4)
White Letter SBR Tires, P255 / 60R15
White Letter SBR Tires, P225 / 70R15
Heavy Duty Battery
AM-FM Radio, stereo with 8-track tape
AM-FM Radio, stereo with cassette
AM-FM Radio, stereo with CB
AM-FM Radio, stereo
Dual Rear Speakers
California Emission Certification
Power Windows and Door Locks
Base Corvette Sport Coupe (1YZ87)
The base price of the 1979 Chevrolet Corvette Coupe without any optional equipment.
A 350 cubic inch, 195 horsepower engine, 4-speed wide ratio manual transmission, leather or cloth/leather interior trim, and T-tops were included in the base price.
Power Windows (A31)
Factory installed power driver and passenger windows.
Power Door Locks (AU3)
Factory installed power door locks.
Removable Glass Roof Panels (CC1)
Tinted glass lift-out roof panels.
Rear Window Defogger (C49)
An optional rear window forced air defogger.
Requires UA1 Heavy Duty Battery when adding C60 Air Conditioning.
Air Conditioning (C60)
Factory installed four-season air-conditioning.
System includes evaporator, blower, condenser, receiver-dehydrator, refrigerant (freon) tank, air intake assembly and duct assembly for both systems.
Includes an integrated heater.
Sport Mirrors (D35)
Outside driver mirror assembly that included a mechanical linkage to control movement from inside the cockpit.
Spoilers, Front and Rear (D80)
Functional front and rear spoilers that decreased drag by 15% and increased fuel economy by about a half-mile per gallon.
Gymkhana Suspension (FE7)
An optional, heavier-duty suspension system for higher levels of performance.
The Gymkhana rear leaf springs contained 9 leafs, though the top leaf is very small. GM identifies the rear leaf springs as an 8-leaf spring.
Included a stiffer front sway bar and stiffer springs.
There were no restrictions on ordering this option – it could be ordered with any engine/transmission combination.
Heavy Duty Shock Absorbers (F51)
Not available with Trailer Package ZN1.
Not available with Gymkhana Suspension FE7.
Optional Rear Axle Ratios (G95)
A selection of optional rear axle ratios.
In 1979, these included: 3.36 (Code OM), 3.55 (Code OH), 3.70 (Code OJ).
Not available with MX1 automatic transmission
Cruise Control (K30)
Cruise control allowed the car to maintain a set speed without the driver depressing the accelerator pedal.
The cruise control option was only available with MX1 automatic transmission.
350ci, 225hp Engine (L82)
Optional higher-output, small block V-8 engine.
Not available in states Florida, Maryland, Oregon, and Washington.
Not available in Boston, Massachusetts; Chicago, Illinois; Des Plaines, Illinois; Grand Rapids, Michigan.
Not available in the county of Cook, Illinois.
4-Speed Manual Transmission, Close Ratio (M21)
A close ratio version of the MM4 4-speed manual transmission.
The gear ratios for the RPO M21 Close Ratio 4-Speed Manual Transmission are: 1st Gear – 2.43:1, 2nd Gear – 1.61:1, 3rd Gear – 1.23:1, 4th Gear – 1.0:1 (Direct).
M21 was a no-cost option but required the optional L82 engine.
Automatic Transmission (MX1)
An optional, three-speed automatic transmission.
The 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 – 2.52:1, 2nd Gear – 1.52:1, and 3rd Gear – 1.00:1.
MX1 was a no-cost option.
High Altitude Emission Equipment (NA6)
Alternate emission equipment installed for vehicles operating at high altitudes.
The high-altitude emission equipment was required for vehicle operation at +4,000 feet.
Manual transmission was not available when choosing NA6.
L82 was not available when choosing NA6.
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.
A new steering column positioned the steering wheel two inches closer to the instrument panel to provide more of an “arms out” driving position, and easier entry and exit.
Includes color-keyed leather-wrapped Sport Steering Wheel.
Aluminum Wheels (4) (N90)
Included four aluminum wheels and a conventional steel spare.
White Letter Steel Belted Radial Tires, P255/60R15 (QBS)
Standard size tires with special raised white lettering.
White Letter Steel Belted Radial Tires, P225/70R15 (QGR)
Optional size tires with special raised white lettering.
Heavy Duty Battery (UA1) – Optional, heavier-duty battery with increased cranking amps/capability.
Required with combination C49 Rear Window Defogger and C60 Air Conditioning.
AM-FM Radio, Stereo with 8-Track Tape (UM2)
The standard/stock radio equipped with an 8-Track Tape Player.
The radio received broadcast in FM 2-channel stereo, FM monaural, and AM monaural.
Includes 8-track tape deck.
AM-FM Radio, Stereo with Cassette (UN3)
The standard/stock radio equipped with a Cassette Tape Player.
The radio received broadcast in FM 2-channel stereo, FM monaural, and AM monaural.
Includes Cassette Tape player.
AM-FM Radio, Stereo with CB (UP6)
The standard/stock dealer installed radio equipped with a CB.
The radio received broadcast in FM 2-channel stereo, FM monaural, and AM monaural.
Full 40-channel Citizens Band radio.
CB mike is stowed on the center console.
AM-FM Radio, Stereo (U58)
A standard/stock dealer installed Corvette radio.
The radio received broadcast in FM 2-channel stereo, FM monaural, and AM monaural.
Power Antenna (U75)
A rear deck antenna that retracts and extends when the radio or ignition is powered off and on respectively. The power antenna extends 31 inches.
Not available with UP6.
Dual Rear Speakers (U81)
Dual rear auxiliary speakers.
Requires UM2, UN3, UP6, or U58.
California Emission Certification (YF5)
Manual transmission was not available when choosing YF5.
L82 was not available when choosing YF5.
Trailer Package (ZN1)
Factory installed trailer package.
The trailer package included the Gymkhana Suspension, a higher-amp alternator and a heavy-duty radiator.
The hitch could support approximately 100 pounds of tongue weight.
Requires MX1 Automatic Transmission.
Power Windows and Door Locks (ZQ2)
Factory installed power windows and factory installed power door locks.
Convenience Group (ZX2)
A group of convenience options available to consumers when purchasing a 1979 Corvette.
The ZX2 Convenience Group included dome light delay, interior courtesy lights delay, headlight warning buzzer, underhood light, low fuel warning light, floor mats, intermittent windshield wipers and and passenger side visor mirror.
High-back bucket seats introduced on the 1978 Pace Car replica became standard in 1979.
Front and rear spoilers found on the 1978 Pace Car replica became optional equipment (RPO D80) in 1979.
Manual transmission Corvettes now have the same shock absorbers as Corvettes equipped with automatic transmissions for a more comfortable ride.
1979 models equipped with the automatic transmission come standard with a 3:55:1 rear axle ration versus the 3.08 from the previous model year for better performance.
The L82 engine gets dual snorkel intakes for the air cleaner for a larger volume of air intake into the engine resulting in increased horsepower and torque.
Also aiding in engine output is is a larger diameter “Y” pipe behind the emission converter and new open flow mufflers to reduce exhaust back pressure.
Cold engine operation is improved with the trapped vacuum spark advance system and driveability is enhance with a new exhaust gas recirculation (EGR) system.
AM/FM Stereo is now standard equipment.
High beam headlights were replaced early in production with high intensity tungsten-halogen for increased visibility.
1979 Corvette Recalls
Make: CHEVROLET Model: CORVETTE Model Year: 1979 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: 15899
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.
UNDER THESE CONDITIONS, THE VEHICLE OPERATOR MAY NOT BE ABLE TO STOP THE CAR, POSSIBLY RESULTING IN A VEHICLE CRASH.
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.
ALSO, CUSTOMERS CAN CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION¿S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).
Make: CHEVROLET Model: CORVETTE Model Year: 1979 Manufacturer: HONEYWELL INTERNATIONAL, INC. Mfr’s Report Date: OCT 19, 2007 NHTSA CAMPAIGN ID Number: 07E088000 NHTSA Action Number: N/A Component: EQUIPMENT Potential Number of Units Affected: 121,680
CERTAIN HONEYWELL FRAM RACING BRAND HP4 AND HP8 OIL FILTERS THAT WERE MANUFACTURED FROM MAY 25, 2006, THROUGH SEPTEMBER 14, 2007, AND SOLD FOR USE AS REPLACEMENT EQUIPMENT FOR VEHICLES LIST ABOVE. THE AFFECTED FILTERS ARE MARKED WITH A DATE CODE A61451 THROUGH A72571 SEQUENTIALLY. THE DATE CODE AND PART NUMBER APPEAR ON THE FILTER HOUSING. FRAM RACING HP4 AND HP8 OIL FILTERS NOT BEARING A DATE CODE IN THIS RANGE ARE NOT AFFECTED BY THIS RECALL. THE GASKET OF THE OIL FILTER BECOMES MORE PLIABLE UNDER HIGH TEMPERATURES AND PRESSURES.
THIS CONDITION MAY CAUSE INADEQUATE SEALING AND LOSS OF ENGINE OIL, POSSIBLY RESULTING IN A FIRE.
HONEYWELL WILL REPLACE THE AFFECTED OIL FILTERS FREE OF CHARGE. THE RECALL BEGAN DURING NOVEMBER 2007. OWNERS CAN CONTACT FRAM CUSTOMER SERVICE TOLL-FREE AT 1-800-890-2075.
CUSTOMERS MAY CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION’S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY: 1-800-424-9153); OR GO TO HTTP://WWW.SAFERCAR.GOV.
1979 Corvette Service Bulletins
1979 Corvette Common Issues
1979 Corvette 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.
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
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.
The adjustments described apply to all carburetors used, except as noted. All adjustments are made with the engine at normal operating temperature.
Idle Speed (1977-1979)
See emission label on vehicle. Set engine for adjustments. Set ignition timing. For carburetors without solenoid and with air conditioner off, turn idle speed screw to set curb idle speed to specifications. For carburetors with solenoid, energize the solenoid, disconnect the air conditioner at the compressor, turn air condition on, set A/T in drive, M/T in neutral and turn solenoid screw to adjust speed to specified RPM.
Idle Mixture (1977-1979)
Idle mixture screws have been preset at the factory and capped. Do not remove the caps during normal engine maintenance. Idle mixture should be adjusted only in the case of major carburetor overhaul, throttle body replacement or high idle CO level as determined by inspection.
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 (1977-1979)
Use choke valve measuring gage J-26701. Rotate degree scale of tool until zero is opposite pointer. With choke completely closed place magnet squarely on top of choke valve. Rotate bubble until it is centered. Rotate scale so that number of degrees specified in opposite pointer. Place cam follower on second step of cam next to high step. Close choke by pushing upward on choke coil lever. To adjust, bend tang on fast idle cam until bubble is centered. Remove gage.
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.
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.
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.
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.
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.
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.
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.
Parking Brake (1977-1979)
Raise the vehicle and remove the rear wheels. Loosen the equalizer check nuts until the levers move freely to the “off” position with slack in the cables. Turn the disc until the adjusting screw is visible through the hole in the disc. Insert a screwdriver and tighten the adjusting screw by moving the screwdriver handle upward. Adjust both sides. Tighten until the disc will not move, then back off six to eight notches. Install the wheels and place the brake handle in the applied position – 13 notches. Tighten the check nuts until an 80 pound pull is required to pull the handle into the fourteenth notch. Torque the check nuts to 70in. lbs. With the hand brake off, there should be no dragon either of the rear wheels.
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.
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.
Clutch Adjustment (1975-1982)
Disconnect the clutch return spring at the cross shaft. Push the clutch lever until the pedal is against the rubber stop under the dash. Loosen the two shaft locknuts and push the shaft until the throwout bearing just touches the pressure plate spring. Tighten the top locknut toward the swivel until the distance between it and the swivel is 0.4″. Tighten the bottom locknut against the swivel. The pedal free travel should not be 1-1/2″.
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.
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.
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.
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.
Change cam lubricator end for end at 12,000 mile intervals. Replace at 24,000 mile intervals
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.
1979 Corvette Dealers Sales Brochure
Download this 1979 Corvette Dealers Sales Brochure for a quick look at the features of the car.