Every week we have at least one customer call and ask us this question, “How do I remove the knob and rod from my headlight switch?” It is a very common problem that everyone encounters the first time they try to do this.

First you will need to pull the stalk on your Corvette’s headlight switch all the way out as if you are turning on the lights. Then look on the switch body for a button (red arrow below). This button allows the headlight rod and knob to  separate from the headlight switch. With the switch separated from the knob and rod you can easily remove the headlight switch assembly from your old dash and replace it with a new one.

We sell Corvette headlight switches, knobs, rods and more. If you ever have a question about a part we sell, or how to install it, feel free to give us a call!

Corvette Interior Dye

This Corvette Restoration Tip is brought to you by Zip Corvette and can be found in our free Corvette Parts & Accessories Catalogs – Request one online today.

Careful preparation is the key to success when dyeing your Corvette’s interior. Cleanliness is essential, so begin by wiping the parts to be dyed with wax and grease remover. This specialty solvent will clean the parts of dirt, interior conditioning products that others may have applied, and the oils that naturally gravitate to the surface of vinyl and leather. Don’t use a strong solvent such as lacquer thinner or you risk damaging the underlying material. After cleaning, lightly but thoroughly sand the surface to be dyed in order to promote adhesion. Fine sandpaper such as # 400 grit is sufficient. Wipe the surface down again with wax and grease remover. Though not essential, it is highly recommended that you apply a coat of primer or Interior Dye Adhesion Promoter before spraying the dye. Besides promoting adhesion, this will lessen the possibility of a reaction between the new dye and the old finish. Good spraying technique is very important! Whether you us an aerosol can or a gun, spray the dye from 8-10″ away and apply uniform, overlapping coats that are wet enough to flow into each other but not so wet as to run. Since dye does not get sanded and polished it’s important to reduce the likelihood of contamination by spraying in a clean environment. It’s equally important to spray the dye in an warm, dry environment to avoid blushing.

For more information on how to dye the interior parts in your Corvette, read our technical article “Dyeing Plastic & Vinyl Parts” at Corvette Magazine.com.

Corvette Shop/Service Manuals On CD

The original Corvette shop & service manuals provided to Chevrolet service technicians for Corvette repair and maintenance are now available on CD in PDF format. The new Corvette Shop & Service Manual CD’s for 1953-1981 will run on both Windows & Macintosh if you have Adobe Reader 7.0 or higher installed.

Each shop & service manual is broken down into basic operating systems and shows how to remove, disassemble and rebuild major components on your C1, C2 or C3 Corvette. Step by step instructions are designed for the novice or professional mechanic and allow you to work on your Corvette at your own pace with the reassurance that you are getting the job done right. Each shop & service manual also includes diagnostics, troubleshooting, required tools, and Corvette wiring diagrams to assist with any aspect of your Corvette restoration. You will truly be satisfied with these manuals on CD as they are loaded with original factory photographs and illustrations from beginning to end.

These hard-to-find factory shop manuals are published by Detroit Iron. The CD contains the information as published in the original paper manuals for 1953-1981 Corvettes. Each CD has been completely revised meaning that all images from the original factory manuals have been re-scanned for clarity, and they even include easy search capabilities. No more flipping through a huge binder!

Common areas included in Corvette Shop & Service Manuals include:

• Brakes
• Steering
• Front and Rear Suspension
• Wheels and Tires
• Axles and Drivelines
• All Electrical Systems
• Engine Mechanical
• Engine Fuel
• Transmissions
• Accessories
• Frame
• Cooling System
• Instruments and Gauges
• Lighting System
• Fuel Tank and Exhaust System
• Body

Corvette Body Repair Guide

Be it poor panel fit, seams showing, or even large-scale damage, the fact is most all old Corvettes have had some sort of body problem. Author Ray J. Shiro shares his 32 years of experience in the Corvette body repair business in this set of step-by-step guides for the do-it-yourself enthusiast. Written in “plain language”, these easy-reading Cd’s (with printable documents) cover location of body seams, seam repair, bonding adhesives, panel removal and replacement, complete front or rear assembly and more.

Volume 1 includes: 1963-1967 Corvette front body panel removal & replacement, headlight assembly removal, replacement & adjustment, body seam repair, body panel splicing repair techniques and a body restoration guide. This midyear body repair guide on Cd includes over 165 photos throughout with detailed explanations and 24 illustrations, which will help make your Corvette’s restoration much easier.

Volume 2 includes: 1963-1967 rear Corvette body panel removal & replacement, crack repair, panel splicing, body seam repair and a body restoration guide. This volume includes over 195 photos with detailed explanations and 17 illustrations that will help you repair or replace your C2 Corvette’s rear body panels.

Corvette Body Repair Guide

Volume 3 includes: 1968-1982 Corvette complete front end replacement, door skin replacement, T-top panels, body panel removal and replacement. Over 180 photos with detailed explanations and 24 illustrations are included in this C3 Corvette Body Repair Guide.

Volume 4 includes: 1968-1982 Corvette headlight assembly, headlight adjustments, door jamb replacement, complete rear body replacement, crack repair, body panel splicing and body seam repair. The 170 plus photos and 11 illustrations are sure to help with the restoration of any C3 Corvette.

Volume 5 includes: 1984-1996 C4 Corvette headlight assembly & adjustments, door jamb splice, front bumper assembly, hood replacement, front lower fender, firewall repair, dog leg panel and a body restoration guide. Over 220 photos and 11 illustrations are included to help restore your C4 Corvette’s body to its original form.

Volume 6 includes: 1984-1996 C4 Corvette complete door skin & door removal and replacement, rear quarter panel removal & replacement, top panel removal and a body restoration guide. Volume 6 of the Corvette Body Restoration Guides on Cd includes over 280 photos and 10 illustrations with detailed instructions for a much simpler restoration.

Corvette Wiper Transmission

To illustrate, each transmission has two spools – one for each drive cable. The inside face of each spool has cast teeth locking them together. When the transmission shaft is pressed down, the two spools separate and an internal spring allows the spools to rotate to their tightest position. Once pressure is removed from the transmission shaft, the spools are locked together again and the cables are tight against the wiper motor drum. When removing the transmission, the operation will require the help of an additional person. With one person pressing down on the wiper transmission shaft to “unlock” the spools, the second person (inside the Corvette) must pull against the cables, rotating the spools against the pressure of the spring. Once all the necessary slack is obtained, the wiper transmission shaft can be released and the spools will lock together. This slack will allow the cables to be removed from the wiper motor drum. The Corvette’s Wiper Transmission can then be removed.

Aluminum Dash Insert

Begin by removing the screws holding the chrome escutcheons at each end of the passenger side grab bar. Slide the escutcheons toward the center of the bar to expose the screws hidden beneath them. Remove these screws and lift the bar out. Unscrew the nuts that retain the insert assembly to the dash by reaching behind the insert. Once the nuts are removed separate the insert assembly from the dash. Once the insert assembly is out you will see how it is put together. The delicate aluminum insert sits on a heavy steel backing and is held by thin stainless steel trim that clips over the edges of the aluminum and steel around the perimeter. The stainless trim is tack welded to the steel backing and you must cut the welds, a task best accomplished with a small grinder or rotary cutting tool. Take care not to cut beyond the weld or you risk damaging a part of the stainless trim that is visible. After the welds are ground pull the stainless off and separate the aluminum from the backing. Glass bead and paint the normally rusty backing and polish the stainless trim. Lay the new insert onto the backing and carefully clip the stainless back into position. Avoid touching the insert as it scratches easily and even the oil from your fingers can blemish it. Gently clamp the assembly so that both pieces of stainless fully seat. Apply a thin layer of two-part epoxy to the area where the stainless meets the steel backing on the reverse side. After the epoxy dries remove the clamps and reinstall your newly restored assembly.

Corvette Brake Caliper

Original Shark-era Corvettes had the lip seal design caliper installed. With that said if you would like to keep your Corvette 100% correct then the lip seal is the way to go. However, be aware that prolonged inactivity and/or worn brake components are the enemy of the lip seal design and can very quickly cause your Corvette’s Brake Calipers to leak. If you enjoy exercising your Corvette heartily, or, conversely, your pride and joy often sits for extended periods, O-ring seals are the better choice. They are superior in design all around and offer the best sealing possible.

Now available at Zip Corvette are both front and rear brake caliper o-ring conversion kits. These kits will allow you to convert your Corvette’s Brake Calipers from the original lip seal design to the long lasting o-ring design pistons. The kits include four o-ring style pistons for front and rear calipers, o-rings, dust boots and caliper fluid seals. There are enough components in each kit to convert a single caliper to the o-ring design.

Corvette Fuel Pump Mount

When changing a fuel pump on any Corvette, the first thing you want to do is remove the gas cap. This keeps fuel from being pushed out of the line from pressure built-up in the tank. Place a catch bucket under the fuel pump lines and disconnect the rubber hoses that connect the frame lines to the Corvette’s fuel pump. Once removed, disconnect the steel line that goes from the pump to the carburetor. On the front side of the block, next to the fuel pump, you’ll see two mounting holes. The upper hole is threaded all the way through the block into the cavity for the fuel pump push rod. Before removing the pump, thread a 3/8” bolt in, lightly tightening the bolt against the push rod. This will lock the push rod in place so that it does not drop when removing the fuel pump. Remove the two fuel pump bolts and the fuel pump will lift out. The fuel pump plate and bottom two bolts do not need to be removed. After installing the new gasket and fuel pump, remove the temporary bolt, releasing the push rod to rest against the fuel pump rocker arm. Reinstall fittings and lines, making sure all threads are properly sealed.

Corvette Door Strap

Installing new door weatherstrip on your Corvette can sometimes cause issues when you go to close your door for the first time. Here is a great way to “break in” the new weatherstrip on your Corvette. Using a small binder strap between the doors is how we break in new Corvette Door Weatherstrip seals during final assembly. This is important if you do not want to tweak your Corvette’s exterior door panels, potentially causing body ripples, especially if the paint work is very refined which allows the tiniest imperfections to be seen. We install J-Hooks to the inside of the door by drilling a small 1/4 inch hole at the bottom or top of the door (with door panel removed) depending on where the rubber is the tightest. Hook the binder to the J-Hooks and tighten, then just click it a notch more every two to three days and this will do the trick. Remove the door catch or striker before doing this for no restriction. Once the doors close easily on their own you can re-install the striker and “voila” perfect sealing and no door distortion! Note it is best to have the seats removed when performing this.

Jeff Lilly is a Corvette Parts Dealer with Zip Corvette. This means that due to his large volume of purchases he receives a considerable discount on Corvette Parts and Accessories. Are you interested in becoming a dealer? Read our Corvette Parts Dealer Programs section for more information.

The risk of exposure exists when materials that contain asbestos are disturbed or damaged. Dust full of microscopic asbestos fibers is then released into the air. There is consistent abrasion on brake pads and clutches and a large amount of the toxic material is trapped inside the brake housing or clutch space. The dust is then released when replacement or repair work is done.

The symptoms of mesothelioma usually do not exhibit themselves until about 15 to 25 years after exposure. At this point, the cancer is usually in its advanced stages and doctors often find it difficult to treat the cancer effectively. This makes a mesothelioma prognosis (more often than not) a bleak one. It is estimated that since 1940 more than six million mechanics have been exposed to asbestos in brakes. The increasing rate of asbestos-related illnesses has resulted in mechanics, veterans and people of other susceptible occupations filing mesothelioma lawsuits to be compensated for their undeserved illness.

Mechanics and enthusiasts who do auto restoration and repair on older vehicles should take the right precautions to avoid asbestos exposure. The Environmental Protection Agency (EPA) has issued a detailed brochure that offers information regarding OSHA’s regulations for commercial automotive shops concerning asbestos.

If you don’t feel comfortable working on your older Corvette yourself, leave it to a professional.

There are three different types of Corvette Body Panels available for 1968-1982 Corvettes. Press molded Panels which are original for 68-72 Corvettes, Hand Laid Panels - replacement for 68-82, and Sheet Molded Composite Panels which are original style for 1973-1982 Corvettes. For more information on each panel and how it is manufactured, continue reading below.

Corvette Pre-Assembled Front End

Press Molded Panels – 1968-1972 factory fiberglass panels were produced in molds that created an exceptionally strong part that were smooth on both sides. To help keep your Corvette as original as possible, Zip offers as many press molded pieces as are available. Panels are manufactured to higher quality standards than possible for hand laid panels, using fiberglass mat and resin placed inside matched male/female molds – then pressed together under high pressure and heat to ensure consistent thickness. Original panels are black in color and do not have a gelcoat surface. Note press molded panels require the use of bonding strips when installed.

Hand Laid Panels – Replacement fiberglass panels are built by layering fiberglass mat and resin into a single mold. Construction of each piece begins with the spraying of gelcoat into a female mold; once cured, alternating layers of fiberglass matting and resin are hand rolled to eliminate air pockets and ensure an overall uniform thickness. Once “popped” from the mold, panels are hand trimmed and ground to final shape. Hand laid panels have a smooth exterior and a rough fiberglass/resin underside.

SMC Panels – 1973-1982 Corvettes were assembled of panels made from a sheet molded composite (“SMC”). SMC panels are formed by a high-pressure mold compressing a mix of fiberglass, resin, catalyst and release agent. SMC pieces are smoother than press molded fiberglass panels and have a marbled appearance – typically gray in color. Note SMC panels require special adhesives for bonding.

1958-1962 Corvette Dash Pads were made from vinyl over a molded foam base. If the vinyl covering is cracked or has shrunk to the extent that gaps are visible, the only effective solution is to install a new pad. Installation of a new pad requires removal of the instrument housing, passenger side grab bar, package tray, aluminum insert, radio speaker grille and rear view mirror. It also requires removal of the interior light escutcheon, trim where the upper dash meets the center dash and complete windshield assembly. The instrument housing is screwed to the dash with five screws that must be accessed from underneath, and tethered by a wide variety of wires and cables that must be disconnected. If you are not familiar where everything goes, it is wise to label each wire and cable before disassembly.

To begin, remove the Corvette’s Steering Column mast jacket lower cover and cover support. These are found right beneath the area where the steering column meets the instrument housing. Disconnect the speedometer and tachometer cables, unplug the wire harnesses to the headlamp switch and ignition switch, unscrew the line to the oil pressure gauge, pull out all of the illumination bulbs, turn signal bulbs, and high beam indicator bulb. Disconnect electrical connections to the fuel gauge, temperature gauge, ammeter and cigarette lighter. Then lift out the instrument housing.

Next, you are going to unscrew the passenger side package tray and then remove the screws holding the chrome escutcheons at each end of the Corvette’s Grab Bar. Slide the escutcheons toward the center of the bar to expose the screws hidden beneath them. Remove these screws and lift the bar out. After unscrewing the nuts, remove the aluminum dash insert. Also remove the radio speaker grille, which is retained by four nuts that need to be accessed from beneath the dash. Remove the rear view mirror, which is held by two nuts that are also accessed from below the dash.

You can now begin removing the Corvette’s Windshield by unscrewing the hinge pillar end caps retaining the dash pad in the area above the upper door hinges. Fold the dash pad up to gain access to the windshield retaining nuts. Go underneath the dash area to access the nuts that run along the cowl beneath the base of the windshield assembly. Once the nuts have been removed, the windshield assembly can be lifted up. Pull the old dash pad off and scrape any foam that remains stuck to the dash panel. The vinyl covering on the new dash pad must be cut to allow mounting of the mirror, speaker bezel, etc. The edges need to be trimmed back as well. The vinyl will shrink with time so it is very important to trim only the bare minimum necessary and leave plenty of overlap beneath everything that mounts over the vinyl. Use interior adhesive to glue the flap of vinyl that sits beneath the windshield but otherwise do not glue the pad down. The instrument housing, dash insert, end caps, and so on will retain the pad once they are all installed.

About 80 years ago, while evaluating the effects on gasoline of various heavy metals, scientists discovered that the addition of tetra-ethyl-lead reduced knocking in automobile engines. Lead also had the added benefit of providing lubrication inside the combustion chambers, which was particularly helpful for the exhaust valves and their seats. Because of these beneficial properties, a minimum number of adverse side effects and its low cost, lead became a staple in gas for nearly 50 years.

All of that changed in the early 1970s, when oil companies began phasing lead out because it was incompatible with the catalytic converters that automakers were required to install. By the late 1970s leaded fuel was becoming quite rare and a few years after that it essentially vanished. This is not a problem for newer cars, which have been engineered to run on unleaded fuel, but can be troublesome for many of the older cars still on the road. While the increased anti-knock properties that lead imparted to gasoline have been addressed with various other additives, the same is not true for lead’s lubricating benefit. Newer engines have been designed to operate without the combustion chamber lubrication that lead provided but older engines are susceptible to certain damage without this lubrication. In particular, the exhaust valves and their seats are vulnerable to accelerated deterioration when an older engine is run on unleaded fuel.

There are two ways to address this problem. The first is with the addition of lead or lead substitute to the fuel in your tank. This creates an ongoing expense and is a little bit of a nuisance but is probably the best solution for cars that are driven infrequently. The second way to deal with the absence of lead is to modify your engine so that it does not require upper cylinder lubrication. This is done with the installation of stainless steel valves and hardened valve seat inserts.

All 1953-1962 Corvettes came with 15”x 5” wheels and full wheel covers as standard equipment. Beginning in 1957 and continuing through 1962, buyers could substitute optional “wide wheels” that were 15”x 5 1/2”. Instead of the standard full cover, wide wheels got a small “dog dish” hubcap that covered only a portion of the wheel.

C1 Corvette

In 1953 and 1954 all Corvettes came with red painted wheels. These were dip painted so they should be red everywhere. Beginning in 1955 wheels were dipped in black primer and then sprayed their final color on the front face. Aside from some color overspray, the backs of the wheels were therefore black regardless of wheel color. Also beginning in 1955, wheel color was determined by the car’s exterior color. Polo White, Gypsy Red, and Pennant Blue exteriors came with red wheels, Corvette Copper got bronze, and Harvest Gold got yellow. In 1956 and 1957, wheel color matched the exterior color with the exception of Polo White cars, the wheels of which were keyed to interior color. If the interior was red the wheels were red and if the interior was beige the wheels were silver.

In 1958 all Corvettes came with silver painted wheels regardless of exterior color. The only possible exception is cars equipped with RPO 276 wide wheels, which may have been painted black. In 1959 all Corvette wheels, including the optional wide wheels, were black.

In 1960-1961 Chevrolet once again painted Corvette wheels to match exterior color. In 1962, cars equipped with optional whitewall tires came with black wheels while cars with standard blackwall tires came with wheels painted to match body color. Optional wide wheels were also painted the same color as the car’s exterior in 1962.

Corvette Dash Harness

Over time, the plastic deteriorates and becomes brittle and cracked, allowing moisture to get into the wire. In turn, the copper corrodes. Ultimately, this process could end in disaster, i.e., corroded wires lead to short circuits – and short circuits have the potential to turn into electrical fires. With vintage Corvettes continuing to climb in both sentimental and monetary value, why gamble on the (usually unseen) condition of an old wiring harness? Cost-wise within the scope of a comprehensive restoration, the fractional expense of new wiring harnesses is your best money spent. Zip’s Corvette wiring harnesses are correct reproductions featuring the same connectors, wire sizes and colors as the originals. Experience new found confidence in your Corvette’s electrical system with all-new harnesses from Zip Corvette!

Cast iron exhaust manifolds will begin to rust at the first sign of moisture, leaving your Corvette’s engine compartment looking decidedly less than “Best of Show”. Begin removing the manifolds by first liberally spraying all bolts with penetrating oil. Repeat this step at least three or four times over the next hour. The last thing you want is a stud twisted off into the base of your manifold – have patience and take your time with the following steps.

Corvette Exhaust Manifold

Once all bolts are well soaked, loosen the three manifold to pipe stud nuts. With a wire brush, clean the stud under the nut and apply more penetrating oil. Now you can slowly remove the nuts. Next unbolt the manifolds from the head (these bolts are grade 8 and rarely cause problems). Bead blast or wire brush the manifolds to clean off all traces of rust, then wipe them down using a small amount of lacquer thinner. Do not wash the manifolds as cast iron absorbs water. After cleaning, apply Calyx manifold dressing. The secret to applying this cream is to slowly rub it into the manifold, working it down into the pores of the cast iron. Do not use too much, as you only want to change the color of the piece. Reinstall the freshly restored manifolds, step back and admire the results!

For an in depth look on how to detail your Corvette’s exhaust manifolds without removal, click here.

Everyone knows Corvette bodies are invulnerable to rust but the same is not true for the chassis. The fully boxed side rails and cross members in 1953-1962 models impart significant strength to the chassis but they are particularly susceptible to rust because water can get trapped inside.

1953-1962 Corvette

If the Corvette’s chassis has a rust problem it normally manifests itself in the rear most crossmember first. Other sections that are especially at risk include the side rails in the areas beneath the doors. Because the rot progresses from the inside out, a problem may not be apparent from visual inspection alone. Poke along the bottoms of the rear crossmember and side rails with a pick tool or tap these areas with a ball peen hammer to expose any weaknesses.

If you discover rust, the best solution is to replace the damaged sections with new reproduction pieces. For the side rails this means cutting out the rotted section slightly beyond the damaged area and welding in new sections. For the strongest repair, weld in an inner sleeve that bridges the seams between the new sections and the original frame.

Rather than repairing a Corvette rotted rear crossmember, it is preferable to replace it. The original crossmember is held on by a combination of rivets and welds and for the best result you should attach the reproduction crossmember in the same way.

Whether or not your chassis requires rust repair, you will want to strip and refinish it during a comprehensive restoration. There are various methods for removing paint, undercoating, rust, and other surface contaminants, including abrasive blasting, chemical stripping, and electro-chemical immersion. With electro-chemical immersion the chassis is placed in a large vat of liquid and subjected to an electric current. The chemical bath and current together completely strip the chassis inside and out. This is the most thorough method of stripping but it must be done by a specialty shop with the right equipment and requires that the inside of the chassis be coated as well as the outside to prevent future rust problems. Chemical stripping is effective but not recommended because it is very difficult to prevent the stripper from getting into the areas between overlapping metal. Abrasive blasting is the most popular stripping method because it’s relatively inexpensive and very effective. The coarse surface texture it leaves behind provides excellent grip for the new coatings you will apply, but it is important to thoroughly clean out all traces of the blast media to prevent it from clogging the chassis’ water drain holes.

For the ultimate in authenticity, refinish your chassis with the original asphalt based paint but for maximum durability and corrosion protection, use a two-part epoxy paint or have it powder coated. For the best of both worlds use epoxy primer and sealer undercoats with old-fashioned asphalt based topcoats.

Installing new U-joints in your Corvette can turn into a costly job. A simple $30.00 repair could grow into the replacement of your entire driveshaft. For a no-hassle removal, you will need a tool similar to Zip Corvette’s U-Joint Removal Tool, or a standard shop press.

1963-1967 Corvette

Begin by removing the retaining clips on the U-joint bearing caps. Support the underside of the yoke with a large socket (1 1/4”) on the bed of the press, and then begin pressing the U-joint with a smaller socket or rod. Make sure the U-joint is square and all pressure is placed onto the bearing cap – this will help keep the yoke from absorbing the pressure and possibly damaging the driveshaft. Continue pressing the U-joint until it can go no further. Remove the cap you pressed out with a pair of pliers, then reverse the driveshaft and press the opposite cap in the same manner. Once out, you will be able to remove the U-joint from the driveshaft.

To install the new U-joint, lightly sand the inside of the yoke to clean out any corrosion or burrs, then spray with WD-40 to make installation smoother. Begin installation of the new U-joint by removing one cap and pressing it halfway into the driveshaft yoke. Now place the U-joint inside the yoke and press the cap all the way in. Press the second cap into the yoke, being careful to align it with the U-joint. Then reinstall the spring clips and make sure they are fully seated into the groove. You are done!

Nearly all of the major parts found in 1968-1982 Corvettes contain a part number and date code. Developing a better understanding of these numbers and codes and how they relate to one another will enhance your enjoyment of the hobby.

Corvette Engine Stamp

The logical starting point for the analysis of part numbers and date codes on any Corvette is the car’s vehicle identification number (VIN). For all vintage Corvettes the first several characters of the VIN indicate the model year, body style, and assembly plant and the latter characters are the sequential number of each particular vehicle. Beginning in 1972 the fifth character in the VIN indicated which engine the car originally came with. The VIN was stamped into a rectangular metal plate that was riveted to the windshield support frame at the driver side base of the windshield on all 1969-82 Corvettes. Every car’s VIN was also stamped into the chassis in at least one place. For most C3s it was stamped into the chassis on top of the side rail on the driver side in both the area beneath the door and the area above the rear wheel. For all C3s the latter half of the VIN, often called the VIN derivative, was stamped into the car’s original engine block. This stamping was on a flat pad just above the water pump mount area on the passenger side. It also was stamped into the car’s original transmission case.

One way to help verify whether a specific engine or transmission is original to a given car is to compare the car’s VIN to the VIN derivative in the stamping on the block or case. A stamping that does not match the car’s VIN almost certainly means the engine or transmission is not original to that car. A stamping that does match the latter half of the VIN usually means the assemblies are original but even matching numbers does not guarantee this because of a practice commonly referred to as re-stamping. In order to make a non-original engine or transmission appear like the original some people will stamp the correct numbers into the parts. They accomplish this by either machining the existing numbers off or starting with a block or case that never had numbers stamped in to begin with. Evaluating the originality of engine and transmission stampings is a science unto itself and if matching numbers are important to you it is best to enlist the services of an expert.

In addition to the VIN derivative, original Corvette engines also have what’s called an assembly sequence. This is stamped into the block adjacent to the VIN sequence. The assembly sequence indicates the engine’s manufacturing plant, date of assembly, horsepower and application. As with the VIN derivative stamping, the engine assembly stamping can go a long way in helping you determine whether a given engine is original to a particular car. But as with the VIN stamping, engine assembly stampings can be “re-stamped” so just having the correct letters and numbers does not guarantee that the engine is in fact original.

Production records for all Corvettes built in the Bowling Green assembly plant still exist but precise assembly dates for C3s assembled in the St. Louis plant are not known. You can however, determine their approximate assembly day with a fair degree of accuracy. For nearly all months of production the final serial number car assembled on the last working day of the month is known and therefore the total production for each month is known. Using this information and your car’s VIN you can determine which day your car was built. For example, if the final VIN for February was 11,000 and the final VIN for March was 12,600 and your car is VIN 11,786, then you know your car was made in March. You also know they made 1,600 cars in March. Divide that number by the total number of working days in the month and you have approximately how many cars were produced each working day and the VIN range for each of those days. Plug your VIN in and you know which day your car was made – give or take a day or two for slight irregularities in daily output.

Once you have the assembly date for you car in-hand you can evaluate the correctness of all of its dated components. All component manufacturing dates have to precede the final assembly of the car and the generally accepted rule of thumb is that they should not precede it by more than 6 months. For example, if your car was assembled on May 8th all of its dated components, such as the alternator, radiator, wheels, engine, differential, transmission and body glass, will be dated earlier than May 8th but no later than about November 8th of the previous year if in fact those components are original. Reading manufacturing dates on most components is pretty straightforward. Typically, a single number represents the year, a letter represents the month with A being January, B being February, and so on, and one or two additional numbers represent the day. For example, an alternator dated 9B21 was made February 9, 1969. In addition to reading date codes it is also important to evaluate the part numbers on major components. All major cast parts, including the engine block, cylinder heads, intake and exhaust manifolds, and transmission case, have a casting number. Most other significant parts, such as the radiator, alternator, starter, distributor, carburetor and wheels, have either a stamped-in part number or a part number tag.

Upon reading this restoration tip brought to you by Zip Corvette, which can also be found in our free Corvette Parts Restoration Catalogs, you may have many questions about the numbers and codes found on your Corvette. If that is the case our Corvette Number & Paint Guides are exactly what you are in need of. Each guide incorporates materials from the GM archives that has been compiled to offer the most authoritative reference available for finding, decoding and verifying the correct part and casting numbers of every engine and drivetrain component for 1955-1982 Corvettes and other Chevrolet models. Each book is loaded with photographs, blueprints, technical bulletins and build sheets all of which will help you easily determine exactly what your Corvette is/was equipped with.