Classic Car Buyer's Guide: 1975-1982 Corvette
By Patrick Smith
If the sound of dual exhausts and swoopy curves in a low lying two seater is exciting, Corvette was made for you. The "disco nightclub" era Corvettes are a great way to enter the hobby at a low cost. They offer performance and plenty of amenities not often found in older models. The 1975-1982 era 'Vettes have styling that blends nicely with modern era muscle cars and usually have air conditioning, power windows, decent four wheel disc brakes and suspensions that are better than older 1960s muscle cars, yet bear a similar appearance to the earlier sharks. Well sorted examples combine the best of the C3 vintage in one ride. This guide will help you spot the difference between a Mako and a Mud Shark.
Year by Year Changes: 1975 was the first year for a small block exclusive drive line. The optional L-82 engine used hood call outs for the first time. It was the last year for the convertibles. 1976 introduced steel sub sections to replace the front fiberglass floor pans in an effort to improve structural rigidity. The highly desirable aluminum mag wheel finally was a production option that year. For 1977, the cowl intake grille was deleted leaving a clean hood. It was the last year for the sugar scoop rear window frame. 1978 featured a new fastback style rear window and a celebration of Corvette's 25th Anniversary. All 1978s had the special Anniversary die cast fuel door emblem. For 1979, Corvettes had new seats and optional mirrored hatch panels which debuted on last year's Pace Car model. In 1980 the car had a redesigned air dam and urethane nose with a prominent rear spoiler. Engine choices increased with the addition of a 305 four barrel V8. The 1981 'Vette was almost identical. 1982 was the last of the C3 generation and a Collector's Edition was built to celebrate the end of an era. There were no 1983 'Vettes made at either plant as engineers retooled to produce an all new 1984 model.
1975 was the first year for 350 only power.
1977 was the last year for the sugar scoop rear window.
All '78 'Vettes have the die cast fuel hood emblem.
1980 'Vette features new front air dam and rear spoiler.
Drivetrains and Popular Options: Engine wise, Corvettes from this era used a small block Chevrolet 350 V8. The base engine was called L48 and the optional high performance model was L82. The latter was often equipped with a four speed manual transmission. Starting in 1980, Corvette offered a 305 V8 as an option. It was a low horsepower engine. The automatic transmission was GM's TH350 three speed and the four speed manual offering was Borg Warner's Super T-10 which was re-engineered in 1975 for GM. The preferred engine by far is the L82 with four speed. You could get a TH400 automatic when you ordered the L82 with automatic transmission.
The 350 engine is reliable and easy to modify for power.
The L48 is adequate in stock form and easy to soup up if more power is desired. The 305 V8 requires a lot more work to achieve similar power due to very small valves and limited cylinder head flow capability compared to the 350. Many 'Vettes with a 305 have been swapped with a larger V8. The rule of thumb when checking a 1970s to early 1980s 'Vette is to assume the engine is non original unless stated otherwise. Even then, you are prudent to check this on your own.
When it comes to car options, Corvette buyers like air conditioning, cruise control, power windows, power door locks, N90 aluminum wheels and mirrored hatch panels on the later models. When it comes to sound systems, you'll find the buyers split into two camps regarding optional Ac Delco radios. The show car crowd like their radios original. AM-FM stereo is good, AM-FM stereo with 8 track is better and if it has the CB unit, that's gold. Those who buy their 'Vettes to drive instead of competing in shows want modern sound systems. Many keep a stock unit in the dash with a hidden system elsewhere. The driver crowd prefer cars that are in excellent mechanical shape. Some like 'Vettes plain for weight savings. Numbers matching cars aren't as important to racing enthusiasts or buyers seeking a clean, sorted out ride. Major packages such as the '78 Pace Car, Silver Anniversary Editions and Collector's Edition are popular. You'll pay a premium on the Pace Car. Remember there are plenty of cars around, so do not panic if one is sold out from under you.
The Indy Pace Car model is a desirable model.
What to Watch Out For: The main thing to watch out for with any Corvette is frame rust and accident damage. The body is fiberglass, but it has metal substructures in the A pillar areas and joins the chassis with bolts, cage nuts and rubber biscuits to isolate noise. 'Vette frames are notorious for rusting out just ahead of the rear wheels. This is a raised section where the independent rear suspension and control arms are attached to the frame. The area between the rear wheel and door opening collects moisture and rusts. It is hard to check with the car on the ground. You can feel around the frame area by hand but the best way to check it is on the hoist with good lighting. Collisions often destroy the cage nuts that hold the frame to the body. I always remove the rear wheel well inspection covers and check the cage nuts inside for rust or damaged metal. On rear and side impact cars, this area is often left improperly repaired since it isn't visible. Since the chassis is open channel, you should inspect the inner rails for rust out and twisting.
Starting in 1976, the floor pans are metal so you should check them for rust since they join the A-pillar sections. Once the frame is verified to be good, you should check the body. The Corvette body is assembled from many pieces using bonding strips to glue them together. You can see the factory bonding strips on the front fenders with the car on a hoist. Replacement panels and filled in damage will be evident unless a whole new panel was used. Factory 'Vette panels are smooth molded on both sides without fibers showing. Aftermarket panels often are rough single side molded. Bonding strips are usually white, rectangular and lie over the two joining panel seams. Torn, missing or unusual strips suggests panel changes or partial repairs using filler.
When it comes to stress cracks the '75-82 'Vettes are good in this area. The only problems spots are the crowns of front fenders and the edges of the rear bumper cover. They can crack when being roughly handled during service work. It isn't necessarily accident damage. Otherwise stress cracks aren't common on these cars. Their presence could be caused by something minor like inferior workmanship such as spraying paint without the required flex additive on the front and rear bumper covers. Cracks on panels suggest previous repair work that's breaking through the paint or an adverse reaction from two incompatible paint coats. Beginners should stay away from long term storage cars or basket cases as the bodywork involved in repairing weathered fiberglass is expensive. The frame is most likely destroyed as well.
Avoid cars like this '76 that was stored outside for decades. The frame could be rusted out and fiberglass repair isn't cheap.
Once you've checked the body and frame, the engine and transmission are next. The 350 is a hardy engine and proper maintenance assures a long life span. The transmissions are very good as well. Your main concern is to watch for high mileage units requiring a rebuild. While not deal breakers, worn components should be considered when negotiating the selling price. Factory original engine and transmissions command the most money especially if it's an L82 four speed.
The IRS should be checked out as well. Worn out components are somewhat expensive to replace, but the main reason you want to check the rear suspension is for worn u-joints. Corvettes have half shafts coming out of the differential joined by u-joints. If a u joint breaks while the car is on the road, the wheel is free to swing around with only the wheel well housing to contain it. This can wind up totaling your car. The IRS saddle should be checked for worn and dried out bushings and leaf spring cracks. The 1980 versions use fiberglass leaf springs and the saddle is aluminum.
Worn or damaged interiors aren't such a big deal with a healthy reproduction supply available. Everything from carpets to door panels is being made. The worst case scenario would be a low production color combo which will require dyeing new pieces to match the original. Some options are expensive such as the AM-FM stereo radios and blue tinted mirror hatch panels. Expect to pay over $750 for good examples. If you're building a car to compete at the national show level, you'll be using new old stock parts and the price for those items is notably higher than a jobber sourced replacement. You'll have to decide early on what you want to do with your 'Vette to avoid expensive hassles later on.
Worn or missing interiors aren't an issue as replacements are available.
Verification & Documentation: Engine swaps are common with 'Vettes. If you're paying top dollar for a show car, have an expert on the model check it with you. These 'Vettes had lots of ways to verify original components with partial VINs stamped on the engines and transmissions. Every notable part was coded and there is lots of information available. It takes time to thoroughly go over a 'Vette but it pays off by protecting you. Genuine number matching examples are scarce from this era because they were considered daily drivers for so long.
The engine partial VIN is located on a machined pad below the passenger side cylinder head. A letter suffix code is present as well, describing what type of 350 or 305 V8 you have. The TH350 automatic has a partial VIN stamped in one of three possible places. It can be above the oil pan rail on the right side, it can be on a boss behind the bell housing flange on the passenger side, or on the driver side housing near the shifter. The TH400 has a partial VIN stamped on the oil pan rail on the driver side. Both transmissions have metal tags with suffix codes attached near the servo housing. Consult a guide for proper codes. Another item to check is the body tag which is installed on the driver windshield pillar. This gives you the paint, interior trim codes and build date of the car. Sometimes it will have other options listed as well. Now you can go shark hunting with success.
Careful shopping will get you a nice shark.