Almost from its start, 1973 was a year full of both great accomplishments and even greater controversies. Technological feats, including the launch of Skylab and the Mariner Programs, the opening of the Sydney Opera House, and the start of the Alaska Pipeline all announced to the world that we were capable of reaching farther – of doing more.
At the same time, it saw the start of the Watergate scandal, an event that would gain international notoriety given advances in technology that allowed television media to beam its signals around the globe – an event that was ushered in, ironically, by Elvis Presley, whose second concert from Hawaii became the first worldwide telecast – and an event watched by more people than the Apollo moon landings.
Perhaps most significant of all, it saw the end of the United States involvement in the Vietnam War with the signing of the Paris Peace Accords.
It is perhaps ironic then that the 1973 Corvette, which would celebrate the 20th anniversary of Corvette’s introduction by Harley Earl in 1953, would also be the first re-design of the C3 since its introduction in 1968.
It was also a testimony to the staying power of Corvette that the car continued into 1973 despite the extensive engineering and tooling cost that GM would incur in bringing the car in-line with the latest safety standards.
The world was once more growing up, and with it, the new Corvette was maturing and becoming more civilized. Its subtle revisions and new design elements would serve to enhance its image while catering to a more discriminating group of consumers and enthusiasts alike.
The changes to the 1973 Corvette, especially when compared to the earlier C3 models, was obvious. For 1973, the Corvette received a new nose treatment on both the coupe and convertible models. The nose was longer (by about two inches), slightly heavier (by about thirty-five pounds), and featured a steel bumper that was covered by deformable urethane plastic that was matched to the body color of the rest of the car.
Although this new nose was the first major appearance change since the introduction of the C3 in 1968, the design was more than just a cosmetic enhancement. To the contrary, the new nose was one of the first examples in engineering design where the styling was dictated by function.
The rest of the front end saw other modifications to their earlier design as well. The 1973 Corvette front fender molds were made to incorporate a simple, recessed air vent design on each side of the car in lieu of the separate cast vent grilles that had been seen on the 1970–1972 models.
This provided a simpler, more streamlined look for the fenders once mounted to the car. Additionally, a new longer hood panel shrouded the parked wiper blades and brought back a cowl-induction system which supplied cool air to the carburetor. The air supply was controlled, according to engine operating conditions, by a solenoid-operated valve that was built into the hood.
While not as notable as the new front end, the 1973 Corvette received a number of other design and safety enhancements that followed the mantra of “form follows function,” (a statement that would become synonymous with the Corvette throughout this and all future generations.) The rear window, which had been removable on earlier models of the C3 Corvette, was now fixed in place. A benefit of this design change was that it provided an additional two-inches of rear storage space due to the removal of the rear window storage shelf.
Another enhancement that was implemented – this time at the direction of a Federal mandate – was the introduction of a longitudinal steel beam in each door to help protect occupants in side impacts. Inside the Corvette’s doors, the heavy fluted steel beams were installed, extending from the door hinges to the lock plates. A design that had been pioneered by General Motors, the beams tied together the body’s steel “birdcage”, and provided an improved method of safely protecting the car’s occupants from injury.
Still another performance enhancement that was included (though not Federally mandated) was the introduction of standard radial-ply tires. By using radial-ply tires, engineers were able to achieve longer tread wear, better wet-weather grip, and added stability when operating the Corvette at speed. At the same time, there was a tradeoff for using radial-ply tires. For one, the new Corvette demonstrated longer stopping distances despite the fact that the 1973 Corvette’s braking system went unchanged from the previous year. Additionally, the new radial-ply tires had lower lateral-G figures on the skidpad, and were rated to operate a maximum speed of just 120 miles per hour.
An option to consumers, the Corvette’s new tires could now be mated to new wheels that would follow the dual “form and function” philosophy. The wheel’s “form” was revised to include an all-new design that was patterned directly from the XP-882 mid-engine Corvette prototype. They featured an eight-inch rim width, a deep-dish section, and eight cooling vents (instead of the ten vents on the experimental car’s original wheels.)
The design was considered striking and more sophisticated by many Corvette enthusiasts than those seen on the earlier C3‘s. “Function” was enhanced by the use of aluminum as the component material, which aided in reducing Corvette’s curb weight by eight pounds per wheel (or 40 pounds per car) without compromising structural strength. Available to consumers as RPO YJ8, only 4 sets of wheels (5 wheels per set), were ordered in 1973, although it is rumored that Chevrolet manufactured a total of 800 sets in all. Early in their production run, Chevrolet rejected the wheels for porosity issues, and recalled the wheels that had been released.
Other design changes to the 1973 Corvette were more successfully introduced and implemented that help to further enhance the overall quality of the car. For one, the body mounts were changed to include a rubber/steel design that helped eliminate annoying vibrations experienced during various driving conditions.
The mounts, which actually utilized a rubber mount encased in a steel sleeve, provided additional cushioning without a loss in rigidity – helping Corvette to maintain a lower level of body roll while improving the ride experience for the car’s occupants. Up front, the problem-prone pop-up wiper panel was replaced by a single rear-hood extension. Elsewhere, engine noise was reduced by adding extra sound
dampening insulation in strategic areas throughout the car. Some of this sound deadening material – specifically an asphalt based compound – was sprayed on to several inner body panels. Additionally, a new, sound-dampening pad was installed under the Corvette’s hood. Inside the cockpit of the car, thicker carpeting and heavier mats were installed in the dash, console and the rear quarters. As a result of this additional damping material, Chevrolet ads that year claimed a forty percent reduction in cabin noise levels.
DID YOU KNOW: The 1973 Corvette’s optional wheels (RPO YJ8) were limited to a single year of production, due to a design flaw in the material that caused Chevrolet to recall the wheels that had been sold. Although only 4 sets of wheels were ever recorded as being sold to consumers during the time of vehicle production, it is believed that Chevrolet manufactured as many as 800 sets of these unique aluminum wheels. These rare aluminum wheels carry the casting number 329381, and featured lug nuts with a recessed center area that had been painted black. While many of these rare wheels ended up in the hands of consumers, it is unknown how many sets of these YJ8 aluminum wheels still exist today.
While concerns about engine noise were certainly addressed, concerns about engine performance continued to linger. For the 1973 model year, federal regulations again emasculated the performance capabilities of every Corvette engine, including the optional upgrades. For the first time since 1956, Chevrolet did not offer a mechanical-lifter engine in the Corvette line. Instead, a choice of three hydraulic lifted units were available.
The base 350 engine (RPO L48), which came standard with the 1973 Corvette, offered consumers a relatively unimpressive output at 190 horsepower. An optional, uprated small block (L82) was also offered with an engine output rating of 250 horsepower. Lastly, a single optional 454 big block (LS4) was offered, producing an engine output of 270 horsepower. Although all three of these engine outputs was diminished from previous years, they did not deter the Corvette from running a quarter-mile time in the mid-15-second range, which was comparable to many of the European cars that were being built at that time – including the Porsche 911E and the DeTomaso Pantera.
Given the changes in the design, and despite the steadily decreasing power of the engines being offered in all versions of the Corvette, the sales numbers for the 1973 model year actually improved over previous years. In all, Chevrolet sold 30,464 Corvettes in 1973, with more than 80% (or 25,521) of those sold being coupes. Prices increased only slightly for 1973, with a base coupe selling for $5,561.50 and a convertible selling for $5,398.50. Interestingly, 4,000 serial numbers were never used/built during the 1973 model year. The last 1973 Corvette’s serial number ended with 34,464, although total production of the 1973 Corvette only totaled 30,464 units. The unused VIN numbers – 24,001 thru 28,000 – were later identified.
During its first six years of development, the C3 Corvette had been transformed from the apogee of high performance represented by the ZL-1 in 1968 to a vehicle more recognized for its higher level of luxury, as portrayed in the 1973 model. While these extremes made many enthusiasts and critics alike begin to debate what kind of car the Corvette should be, it was this same debate that had fueled the continuation of the Corvette since its introduction in 1953.
Two-door convertible/coupe, front engine, rear wheel drive
St. Louis, Missouri
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.
Type and Description: Independent, SLA type, coil springs with center mounted shock absorbers, spherical joint steering knuckle pivots.
Front Coil Springs
Make & Type
10.27 x 3.80; 130.84 x 0.606
Front Stabilizer Bar
Hot rolled steel
.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
Variable rate 9-leaf
Chrome carbon steel
Length, width, height
48.60 x 2.25 x 2.121
Caliper Disk – 4 Wheel Hydraulic
Delco Moraine, vacuum power unit; integral
Drum diameter, front (in.):
11.75 x 1.25
Drum diameter, rear (in.):
11.75 x 1.25
Swept Drum Area Effective area:
Wheels & Tires
Wheels & Tires Specs
Short spoke spider, welded steel
15″ x 8.00
GR70 x 15 — Blackwall Steel Belted Radial
GR70 x 15 — White Stripe Steel Belted Radial
GR70 x 15 — White Letter Steel Belted Radial
24 psi (cold), 30 psi (hot)
24 psi (cold), 30 psi (hot)
Steering Specs – Manual Steering
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.
Wheel Diameter (in.)
Turns, Stop to Stop
37 ft. (outside front), 39 ft. (outside front)
Steering Specs – Power Steering RPO N40
(Specifications are the same as Manual Steering except the following):
Hydraulic; pump powered cylinder assisted linkage
Wheel Turns (Lock to Lock)
1973 Corvette Exterior Dimensions
Hard Top Dimensions
Exterior Dimensions (Hardtop)
Interior Dimensions (Hardtop)
Total Body Width:
Front Track Width:
Rear Track Width:
Min. Ground Clearance
Soft Top Dimensions
Exterior Dimensions (Soft Top)
Interior Dimensions (Soft Top)
Total Body Width:
Front Track Width:
Rear Track Width:
Min. Ground Clearance
Exterior Dimensions (Coupe)
Interior Dimensions (Coupe)
Total Body Width:
Front Track Width:
Rear Track Width:
Min. Ground Clearance
2 – Driver & Passenger
Curb Weight (lbs)
Interior Passenger Volume (cu. ft)
Interior Trunk Volume (cu. ft)
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 454ci. engine
12 Volt, 62AH for 350ci. engines
12 Volt, 80AH for 454ci. engines
Vehicle Assembly Location. S – St. Louis, Missouri
4XXXXX (Eighth thru Thirteenth Digits)
Plant Sequence Numbers.
The last six digits begin at 400001 and run thru 434464, accounting for 30,464 Corvette Coupes/Convertibles built in 1973. 4,000 serial numbers were unused for the 1973 model year. Each Vehicle Identification Number (VIN) is unique to an individual car.
1973 Corvette Vehicle Serial Number Plate
For all 1973 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.)
1973 Corvette Body Number Trim & 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., 1972., B – Sep., 1972., C – Oct., 1972., D – Nov., 1972., E – Dec, 1972., F – Jan., 1973., G – Feb., 1973., H – Mar., 1973., I – Apr., 1973., J – May, 1973., K – June, 1973., L – Jul., 1973
01 – Designates the Day of the Month.
400 – Interior Trim code. 400 – Black (Vinyl)
910 – Exterior Color Code. 910 – Classic White
1973 Corvette Engine Identification & Engine Number
All engines are stamped on the top front of the right-hand bank of cylinder and case.
Engine Identification Example:
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.
CKZ – Type Designation. CKZ – 350ci 190hp, manual transmission.
Engine Number Example:
1 – Division. 1 – Chevrolet
3 – Model year. 3 – 1973
S – Assembly Plant Designation. S – St. Lo
1973 Corvette Transmission Identification & Transmission Number
4-Speed (Muncie) – Stamped on the top right side of the case at adapter.
Turbo Hydra-matic Automatic – Name plate tag on right-hand side of case.
Transmission Identification Example:
WD – Type Designation. WD – 4-Speed / CK – Turbo Hydra-matic
P – Source Designation.
P – Muncie
3 – Year. 2 – 1973
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.
1973 Corvette Factory Options
Base Corvette Sport Coupe
Base Corvette Convertible
Custom Interior Trim
Custom Shoulder Belts (std with coupe)
Auxiliary Hardtop (for convertible)
Vinyl Covering (for auxiliary hardtop)
Rear Window Defogger
Optional Rear Axle Ratio
454ci, 275hp Engine
350ci, 250hp Engine
4-Speed Manual Transmission, close-ratio
Turbo-Hydro-matic Automatic Transmission
Tilt-Telescopic Steering Column
Deluxe Wheel Cover
White Stripe Steel Belted Tires, GR70x15
White Letter Steel Belted Tires, GR70x15
Heavy Duty Battery (std with LS4)
AM-FM Radio, Stereo
Map Light (on rearview mirror)
California Emission Test
Cast Aluminum Wheels (5)
Off Road Suspension and Brake Package
Base Corvette Sport Coupe (1YZ37)
The base price of the 1973 Chevrolet Corvette Coupe without any optional equipment.
A 350 cubic inch, 190 horsepower engine, 4-speed wide ratio manual transmission, vinyl interior trim, and T-tops were included in the base price.
Base Corvette Convertible (1YZ67)
The base price of the 1973 Corvette Convertible without any optional equipment.
A 350 cubic inch, 190 horsepower engine, 4-speed wide ratio manual transmission, vinyl interior trim, and a convertible top were included in the base price.
Custom Interior ( — )
Optional interior trim upgrade that included a number of custom modifications to the base interior.
The custom interior trim includes leather seat trim, wood-grain accents and carpet trim on door panels, wood-grain accents on the console, and cut-pile carpeting.
Power Windows (A31)
Factory installed power driver and passenger windows.
Custom Shoulder Belts (A85)
An addition to the standard lap safety belt that crosses over the shoulder for added safety.
The shoulder belts option was 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 Defogger (C50)
An optional rear window forced air defogger.
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.
Includes an integrated heater.
Manually controlled by knobs on instrument control panel.
Optional Rear Axle Ratio
Rear axle ratio selection.
Power Brakes (J50)
Vacuum power assisted brakes; includes dual circuit master cylinder.
454ci, 275hp Engine (LS4)
Optional high-output, big-block V-8 engine.
350ci, 250hp Engine (L82)
Optional higher-output, small block V-8 engine.
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).
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 Automatic Transmission was a no-cost option with the base 350 cubic inch, 190 horsepower engine, but cost an additional $97 when ordered with the 454 cubic inch, 275 horsepower LS4 engine.
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.
Deluxe Wheel Covers (P02)
Optional deluxe wheel covers.
White Stripe Steel Belted Tires, GR70x15 (QRM)
Standard size tires with a special 3/8″ wide white sidewall stripes.
White Letter Steel Belted Tires, GR70x15 (QRZ)
Standard size tires with special raised white lettering.
Heavy Duty Battery (T60)
A larger battery with added cranking power and capacity.
This option was included when the LS5 was ordered.
80AH battery with 90 plates.
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.
16-transistor 9-diode circuitry.
Fixed height rear antenna.
AM-FM Radio (U69)
A standard/stock dealer installed Corvette radio.
The radio receives broadcast in FM monaural, and AM monaural.
16-transistor 9-diode circuitry.
Fixed height rear antenna.
Map Light (on rearview mirror) (UF1)
Light mounted on inside rearview mirror.
California Emission Test (YF5)
An assembly line emissions test to conform with California registration requirements.
Not available when the LS4 engine was ordered with the car.
Cast Aluminum Wheels (5) (YJ8)
Special cast aluminum wheels with center caps.
Off Road Suspension and Brake Package (Z07)
Stiffer suspension/brake package for more rugged driving conditions.
Available with optional engines RPO L82 and LS4 only.
Required RPO J50 and M21.
Z07 was not available with RPO C60.
The front bumpers were modified from the 1972 model year to withstand new federal 5-mph standards. The updated bumpers added thirty-five pounds of weight to the vehicle.
A forty-percent reduction in cabin noise was obtained by using sound deadening spray on material in inner panels and sound deadening pads on the inner-hood surface.
To reduce road vibration in the vehicle, rubber mounts with steel sleeves were added to the chassis.
An overflow coolant reservoir was added to aid in coolant temperature.
To increase side impact protection, steel beams were added to the doors on the 1973 model Corvette.
The rear window in the 1973 Corvette was fixed and no longer removable. Zora Arkus-Duntov stated that the removal of the rear window created too much interior air buffeting and that this, not the cost savings, was the reason that the 1973 Corvette featured a fixed window.
1973 was the first year radial tires were offered on a Corvette.
The lifting windshield wiper panel was deleted from the 1973 Corvette, but a new hood with rear cold air induction was introduced.
1973 Corvette Recalls
Make: CHEVROLET Model: CORVETTE Model Year: 1973 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
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).
1973 Corvette Service Bulletins
1973 Corvette Common Issues
1973 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 (1972-1976)
The idle stop solenoid requires two idle speed settings. The curb idle speed is normal engine idle speed, the low idle speed is set for conditions when the solenoid is de-energized, as when the ignition is turned off. This prevents engine run-on. Idle speed adjustments are made with the engine at normal operating temperature, with the air cleaner on, choke open, air conditioning off, and fuel tank hose from vapor canister disconnected (on later models). Set parking brake and block driving wheels. Disconnect electrical connector at idle stop solenoid. With automatic transmission in Drive, or manual transmission in neutral, turn low idle screw to obtain low idle speeds of 500 rpm, reconnect electrical connector to solenoid and crack throttle slightly, to extend solenoid plunger. Then turn approximately 600 rpm for automatic transmission models in Drive, or approximately 850 prm for manual transmission models in neutral. Shut off engine and reconnect fuel tank to vapor canister.
Idle Mixture (1972-1976)
The idle mixture is factory preset and the screws are capped with plastic limiter caps. These caps allow about one full turn for adjustment. If more is required remove the caps or break off the tabs with needle nose pliers. Adjusting the idle mixture is done with the engine running at normal operating temperatures, with the air cleaner on, choke open, air conditioning off, and fuel tank hose from canister disconnected. Set the parking brake and block the driving wheels. Put automatic transmission in Drive; manual transmission in neutral. Turn in or out one idle mixture screw at a time to obtain smoothest, fastest idle speed; then adjust the other screw to make engine run even smoother and faster. A basic starting point for adjusting screws is four turns out from fully in position with needle just touching seat. Readjust idle speed if necessary. Reconnect fuel tank hose from canister.
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.
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.
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.
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.
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.
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.
1973 Corvette Dealers Sales Brochure
Download this 1973 Corvette Dealers Sales Brochure for a quick look at the features of the car.