Determining Matching Numbers

By Mike "Doc" Cobine ...... ( Email Me )
18 December 1996 Updated June 28, 2004

This section is under construction and will change as time permits.

Matching numbers is a term tossed about with ease, as is restoration. Both are found in most Corvette ads today as an indication that this Vette is somehow better to buy than one without. This document will attempt to clarify some of the issues and show how to determine what matching numbers really are.

Restorations, Inflation, and Investments

Car restorations have been going on for many years. It is not a new fad, and yet it is, since suddenly it is in vogue to restore a car, especially a Corvette, for resale. Part of this was the appreciation of the value of the restored car compared to the appreciation of your money in the bank. Due to inflation eating a person's savings in the bank, many invested in cars as the selling price could be adjusted to compensate for the rise in inflation.

While some performed restorations on Corvettes in the '60s, most were unknown and were not completely to factory specifications due to an inability to obtain factory original parts. As used Corvettes were quite cheap in that era, investing heavily in parts was for the love of the car only and often shortcuts and compromises were made to functional and correct appearing items.

Most antique car restorers by this time were concentrating on great detail in restoring cars, as to not just correct in appearance, but correct in parts, such as the original bolts with the original head patterns, original upholstery, and so on. In the mid '70s, David Burroughs restored a '65 Corvette and started a standard for others to follow. While his book makes it seem like this was a monumental event, the reality is that his car was virtually in "like new" condition, still having factory stencils and chalk marks intact on the frame. Much of the restoration of the chassis was thorough cleaning to preserve the original items, where most attempting restoration on a 10 year old or older Corvette usually finds 10 years' worth of rust, dirt, and gunk from daily driving. Still his book set a standard that the better than factory show appearance given many Corvettes of the era was not the appropriate manner to restore one, but to give detail to factory markings, factory imperfections, and make it appear the way the factory built it.

With the National Corvette Restorers Society and the Bloomington Gold groups giving direction and a place to shine for restorers, restorations began in earnest for Corvettes in the '70s. With all the hard work and material involved, these cars began to command a higher price than the typical Corvette of the era that was driven and maybe modified extensively. With each restored Corvette came more interested people who willingly paid higher prices on cars and thus the price of Corvettes began climbing. In 1970, many early Sting Rays could be found from $1200 to $2000. In 1974, most Sting Rays could be found from $2000 to $4000. By 1976, restored or original 1963 coupes were commanding as much as $8,000 (although most Sting Rays were still in the $2500 -$4500 range). This climb was noticed and many began to invest, such that by the mid '80s, the prices were climbing to unbelievable heights.

Just What is Restoration?

In the strictest sense, restoration is returning the car to a previous form. Most restoration groups believe that unless the car is restored to some historical significant form and event, such as the 1963 Grand Sports or some race cars, the car should be restored to the way it left the factory. This means exactly the way it left the factory, not how it could have left. Restoring a 1963 coupe 300 hp Sting Ray means returning it to exactly the way it left, with the original parts preferred and correctly-dated and numbered parts if the originals are not available. Making it a 360 hp fuel injected coupe is not restoring it, even if all correct parts are used, as it was never a 360 hp coupe. It cannot be considered original if it was never that to begin with.

Creating a 360 hp coupe from a 300 hp coupe is a counterfeit. While there is nothing wrong with creating any car you wish, as this was the basis of all car customizing, it is wrong if the intent is to defraud a buyer or show judge by passing off a 300 hp coupe as a 360 hp coupe.

When prices rose drastically in the mid '80s, the 1967 coupes with the 435 hp engine were approaching $100,000 in price while 300 hp coupes were around $30,000. This led to many cars being counterfeited from 300 hp versions to 435 hp versions. Depending on the skill of the counterfeiter, the buyer may never know. However, they are still fakes.

Today, the NCRS uses judging guides that clarify what is right and wrong on any given car. There are still exceptions that they miss, as being a production car, changes occurred and workers didn't follow the "rules" when installing parts. But for the most part, the judging guides are the best source of how to determine whether a car is authentic or a fake.

As such, the strictness of the rules in true restoration is that even though you hate that green or red interior, you cannot change it. The same holds true with that Burnt Orange or the Arctic Blue paint. For this reason, the creative ways of custom cars holds a definite appeal. If you buy an orange Corvette with green interior, and hate the color, you can repaint it black with a white interior, or white with a saddle interior, or however you like.

If you really want an L88, but can't find one or afford the $100,000 price someone is asking, then build your own. I built an L88 engine for $2500. You can easily build an exact factory replica engine for under $5000 and have 550 horsepower under your hood.

Customizing has one rule - make it how you like it. But be prepared for many to give you grief over your choice as it is not "restored". Restoration has many rules and you must adhere to all of them or the car is not restored. Restoration can be very expensive due to the man-hours and expenses incurred. This is part of the reason for the high prices of restored Corvettes.

One final thing to remember - matching numbers and date codes do not make a car run better, longer, faster, or anything. It merely means the car is the same as when it left the factory. In many cases, you may find a restored Corvette runs worse than its unrestored counterpart as modern technology in items like tires, brakes, shocks, and so on has advanced for a good reason - the old stuff was not very good compared to today's parts. If you are a history buff wanting to preserve history or an investor who wants to make a buck, then you must ensure the car you buy is restored fully or ensure that you restore it fully to sell. If you are a Corvette enthusiast who desires performance and fun, then restoration is a very expensive path to what can be obtained in many cheaper ways.

So What Are Matching Numbers?

Many claim matching numbers for their Corvettes but most have no idea what this really means. Once matching numbers meant that the parts were the correct ones for that car. In the case of the matching numbers on the block, including the partial VIN on the stamp pad, this implied originality. A car that had a matching numbers block had the original block. However, there have been cases for several years of counterfeit number pads. Now NCRS does not consider that to be counterfeit, but restoration. So if you find the numbers including the VIN on the engine pad matching, you need a lot more proof that this engine is really original. It may just be a restamp. Buyer Beware!

There are many levels of numbers that should match, and I'll list some of them here.

 Body
VIN The Vehicle Identification Number of your car. From '53 to '60, it is in the driver's side door jam. From '60 to '62, it is on the steering column in the engine compartment. From '63 to '67, it is under the glove box. From '68 to '82, it is in the driver's side windshield pillar.
Engine
Casting Number The part number cast into the block when made. See Engine Block.
Casting Date The date of the casting of the block.  See Engine Block.
Partial VIN Stamped on the engine pad located in front of the right head. An engine identifier is also stamped here.  See Engine Block.
Bellhousing
Casting Number The part number cast into the right side near starter.
Transmission
Casting Number Part Number cast into the case and tailshaft when made.
Date code Usually the casting date is in the body but this is the case date. The assembly date is stamped in as part of identifier code.
Partial VIN Stamped along top of mounting ear in some, along joint of main case, or on a raised pad in the main body (newer T-10).
Rear End
Date code Cast in drivers side of housing for the case of '63-'79. In straight axle '53 to '62 Corvettes, the identifier is stamped on the front right side. In the IRS, the assembly date is stamped in identifier on the bottom flange.
Gear ratio Stamped in bottom flange as part of identifier as a letter code, such as AW.
Alternator/Generator
Part Number Stamped on top with date and amperage rating.
Date Code Stamped on top along with amperage rating and part number.
Water Pump
Casting Number
Casting Date Code Cast on front of the pump.
Radiator
Part Number Stamped in aluminum, embossed in copper.
Date Code Stamped in Aluminum.
Distributor
Part number Stamped in aluminum housings and embossed on a tag on iron units.
Date Code Same as Part Number
Window Glass
Date Codes Each window has its own as part of the marking.
Carburetor
Date Code Either on brass tag or stamped in air horn or body, depending on the carb.
Part Number Either on brass tag or stamped into air horn or body, depending on the carb.
Fuel Injection '57-'65
Part Number Stamped on a metal tag on the left front of the plenum.
Date Code
Serial Number Stamped on side of Plenum for the first hundred or so in 1957 and then were stamped on the metal tag. The serial number does not have to correspond to the car's serial number.
Heads
Casting Number Usually cast on top under rocker arms.
Date Code Usually cast on top under rocker arms.

Casting Numbers

When a part is cast, the mold has a part number and a date code set so that it is part of the mold and the part is forever identified. Most older Corvette parts such as heads, blocks, and manifolds, usually have a 7 digit casting number beginning with 3 to identify the part.

Engine Block

On most blocks, the casting number is located on the bellhousing flange behind the driver's side head. The casting number does not usually correspond to any engine part number as the engine part number is for the assembly, not the casting.

  

Cylinder Heads

The casting number is usually in the area under the rocker arms. Years of baked oil may fill the numbers to make them hard to read. On some heads, partial numbers were found on the intake runners on the block side, such as the 461 and 462 heads.

  

Intake Manifolds

Usually on the rear runner on top.

 

Exhaust Manifolds

Usually on the outside of the manifold. Small block Ram Horn manifolds usually have this on your left as you view them. The big block manifolds are down the side.

  

Transmission

Casting numbers are on both the main body and the tailshaft housing, usually on the right side.

  

Rear End

The casting number is located on the right side near the prop shaft.

  

Water Pump

The casting number is on the front of the body.

Date Codes and Where Are They?

Almost every mechanical part made for a Corvette has a date code, either cast or stamped into it. These simply identify when the part was made. To the factory, this date probably made sure that they didn't leave any stock laying on the shelf too long, although if you have ever watched any factory production line run, it is doubtful if anyone ever reads the dates. The purpose of the date to Chevrolet was probably to ensure a means to track any defects should they arise. If a part dated March 3 and one dated March 21 were both defective, attention could be paid to those parts built between those dates for other possible defects.

Today, these are used to determine if the part is correct for that Corvette, as an engine with a date code of D 16 5 (April 16, 1965) could not be correct for a '63 Corvette as the engine was made after the car was made. Parts too early are usually not correct either, as they would have been installed on an earlier vehicle, such as a B 23 3 (Feb. 23, 1963) in a '67 Corvette. NCRS provides a window of 6 months on date codes prior to the build date of the car. Obviously, a part on a car could not have been made AFTER the car was made. (See Exceptions.) But given how new items were constantly loaded on shelves, with existing items being shoved further back each time, a part could sit for many months before being assembled on a car. Usually, the parts were used within a few days or weeks but there are many documented original cars that have parts several months old.

Be sure to notice that some parts have both a casting and a stamped date code. These can be several days apart. The stamped date code is when the part was assembled and should be the one considered.

Engine Block

The date code on a SBC is typically on the bellhousing flange behind the distributor. On early big blocks, it was on the passenger side near the pan rail, but later (1970) moved up to the same location as the SBC.  See Engine Block.

Usually the date is given as a letter, a number and then a number, such as B 23 3 which is for February 23, 1963. With any engine still having ignition shielding on, you have a very hard time to see the date. A good flashlight and a wire brush to clean any dirt are a must, even with the shielding removed.

Cylinder Heads

The date code is located on top under the rocker arms. You must remove the valve covers to see them. Often lead deposits in old engines have filled the numbers and letters so they are hard to read. Often the rockers are in the way.

Intake Manifold

The small block usually has the date on the driver's side rear runner. The date is typically below the casting part number. The firing order (18436572) is usually cast on the front runner so do not confuse it with the part number. Some big block intakes have the date cast under the intake so that you must have the intake off the engine to see it.

Exhaust Manifolds

The casting numbers on the Ram horn manifolds are on the outside near the 1-3 or 6-8 cylinders. On the big block manifolds, it is found low near the outlet. The date codes on the Ram Horn manifolds are found on the opposite end. On the big block manifolds, the date code is found on the back side.

Transmission

The Borg Warner transmission has a date cast into the main body and tailshaft in the early T10s. Some later T10s ('70s) have it also. Usually it is found on the passenger side. The Muncie has a date cast on the tailshaft. Unfortunately, these casting dates are the ones that the castings were made, not the transmission. A stamped number usually contains an assembly date.

Rear end housing

The housing for the 1963 to 1979 differential has a casting date on the drivers side. Again, this is the case date code. The assembly date is stamped in the bottom of the case on the lip where the cover mates.

Alternator

The date code is stamped into the housing.

Water Pump

The water pump has a date code cast into the body in the front but the pulley must be removed to see it usually.

Carburetor

Most of the earlier carburetors were built by Carter and had an identifier tag attached to a cover bolt. This tag had the part number and date code. On Holley carbs, the List Number is stamped on the drivers side air horn in front along with either a 3 digit or 4 digit date code. The Rochester QuadraJet has a stamped number on the driver's side on a vertical pad.

Exceptions

Obviously, my biggest gripe with most restoration groups is their inability to accept that there are exceptions. These were production cars produced by a lot of guys who wanted to punch out and go home, not artists creating an American legend. Most of what you see in restoration books and here hold true, but exceptions do arise. If you see something that you have a gut feeling is right, it may be. If the original owner claims it was never changed, it probably hasn't. If a car salesman claims it, let the buyer beware.

The purpose of NCRS, according to their books, is the "restoration, preservation, and history of the Corvette", which they often overlook in their judging manuals by deducting points for anything that is not "right" without regards to production deviation. Some vehicles have had original items removed because NCRS said they were wrong, only to discover later they were correct. The history is usually obliterated when a car is restored, as the significant part of many cars is what happened AFTER they left the factory, not the assembly at the factory. (BTW, I am an NCRS member.)

Dates after the Body Date

Many forget that the body date is just that - the date of the body. When A.O. Smith bodies were being shipped to St. Louis, they often sat outside waiting for their place on the line. They had dates that were more than a day or two before the final assembly. It is possible that some may have been waiting outside for a long time, such as a couple of weeks. Now if a date code on a part is close to all of the other major parts, but is after the body date, the possibility is strong it is correct.

The Mysterious CE Block

The CE is often defined as Chevrolet Engineering, Chevrolet Engine, Customer Engine, and Crate Engine. I have never heard a definitive answer. The CE block was a replacement engine that is accepted today as having been only a warranty item. The engine pad carries a CE code instead of the traditional codes on production engines. The VIN is usually not stamped in the pad, but occasionally is in a very rough manner, often misaligned and irregular depth, due to being hand stamped at the dealer, if at all. These are relatively rare if in a Corvette within their warranty period as they would indicate a Corvette that Chevrolet warranty work was performed on and the original engine was destroyed. These are the only cases of Chevrolet intervening in the life of a Corvette once it left the factory since engine replacement required Chevrolet management authorization and most warranty work is simply handled by the dealer.

A few CE blocks have shown up in a few cars where the dealer appears to have installed a CE as a non-warranty engine. These were outside the warranty period. It may be that the CE was not a warranty only item but was used as any dealer installed engine. However, as '60s Corvettes sold for around $2000 in the early '70s, having the dealer install a $1000 or more engine was rather foolish with the great availability of $100-$175 used engines and may have just made a dealer installation a very rare occurrence.

Typically, the stamp pad has a CExxxxxx stamped on it. Most reporting seem to have a 6 digit number. A few have a suffix similar to those on the production engines. I do not have enough information to determine what the number meant and any pattern to the suffixes, as to if they were long blocks or whole engines. Some typical styles of stamping are:

Information that has become known recently shows that these numbers have no meaning except a year and a sequential number. Thus, if a 300 hp 327, a 350 hp 327, a 385 hp 427, and then a 195 hp 283 were to come down the line, they could be stamped CE912345, CE912346, CE912347, and CE912348, all for 1969.

You can help if you have a CE block by sending any information you may have. You could fill out the survey at http://www.oocities.org/MotorCity/Downs/3000/ceblock.html.

New Information on CE Blocks

Refer to the Survey of CE Blocks in Chevrolet Cars page for additional information.

The C stands for Chevrolet, E stands for Engine (T would be Transmission), and the first number is the year. Then there is a serial number for the engine, based on the xxxth engine that year. The serial is 20,000 to 49,999 for Flint and 50,000 to 79,999 for Tonawanda. For example, CE950327 is a Chevrolet engine from Tonawanda for 1969 and was the 327th produced, not that it was a 327. (It could be, but that would be an incredible coincidence.)

According to the Camaros.org site, these were not necessarily warranty items. According to John Hinckley, a Chevy engineer at the time, these blocks were part of a program to track warranty expenditures at GM as part of the 50,000 mile/5 year warranty that went into effect at the same time the muscle car era began. According to Michael Hanson, paperwork that crossed his desk indicated this meant all warranties, not just new car warranties, but engine assemblies sold over the counter also.

Reference Material

No matter what I put in here, you cannot beat what has already been written and continually updated. Some excellent references you need to get are:

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