Explain Numbers Matching
05-14-2005, 12:47 PM
#1
Racer
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Explain Numbers Matching
I am new to this. When you say numbers matching, does this mean all serial numbers are the same ie. block, tran.?
Is there a site that I can read more?
Love my vet.
1972 350 AC
Is there a site that I can read more?
Love my vet.
1972 350 AC
05-14-2005, 02:16 PM
#2
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To be truely "numbers matching", the engine block stamp and the VIN in the windshield will match exactly. (I believe there is a number on the frame, but this is also the VIN). Stamped and cast numbers on the other pieces of equipment on the car will match certain date ranges and types of stamps codes to be considered correct. The numbers of these items (like transmission, differential, windshield glass, alternator, pumps, bellhousing, radiator, etc.) will show that they were manufactured at the correct time to be installed on the car.
Not sure about a website with all this info in one location. I know Vette magazines have covered this also. Perhaps someone else will chime in...
Not sure about a website with all this info in one location. I know Vette magazines have covered this also. Perhaps someone else will chime in...
05-14-2005, 02:37 PM
#3
Melting Slicks
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The above post is pretty correct on all accounts. The transmission main case(passenger side) and engine block pad(passenger side) will contain a set of alpha-numeric characters that contain a derivative of the vin plate number. Also the frame(driver side) will be stamped again in 2 places with this same derivative of the vin. These stamping DO NOT contain the complete vin stamping that is located at the lower winshield post area.
This would be the ONLY 3 areas that could remotely be considered matching #'s, as all other components do not match anything on the vin plate.
This would be the ONLY 3 areas that could remotely be considered matching #'s, as all other components do not match anything on the vin plate.
05-14-2005, 05:16 PM
#5
One of the most misused and misunderstood phrases in the Corvette restoration hobby is "numbers matching." The term probably originated when many cars began to be restored back to the way the factory had originally built them. It seems these cars were the first to be truly restored back to originality, in contrast to typical "hot rod." In any case, a “matching numbers” car not only appears in original factory condition, but all pertinent identification numbers, as well as all casting numbers and dates, are correct for the specific model and pre-date the final assembly date of the car. Many people, from those who have large collections of cars to people who have only a vague interest in the hobby, have their own interpretation of what a numbers matching car is. Many hobbyists use the term loosely, with no clue to what it actually is.
To say that this situation is creating a major problem in the Corvette hobby is a vast understatement. The problem lies in the fact that thousands of dollars are being invested into many "matching number" cars, which in fact are complete forgeries, built for the primary purpose of selling an incorrect car as a documented original. Many enthusiasts are unsure as to what composes a correct car. Much of the information that has been published to date in this area has been incorrect in several aspects. We want to clarify what is meant by "numbers matching" and how it pertains to you.
We should also take note of the fact that many cars suffered blown engines, transmissions, and rear axles in the musclecar era. Because the term "numbers matching" has been used so freely, many fine cars are now forged or faked to appear original for a decent resale value. Just remember that a car is only original once, which have been cleverly documented to be original "numbers matching" cars. There is a simple basic procedure to follow that will keep you from being burnt by buying a counterfeit Corvette.
Before we go into detail, let's interject a basic underlying principal: knowledge is the ultimate and only way to stop counterfeiting. Before you ever set out to acquire or restore a Corvette, become as informed as you can about the specific model you are interested in. There are literally hundreds of clubs for any year and model Corvette. Almost all have technical advisors and newsletters to help inform their members of new developments in the "numbers matching" area. Many provide services to help you decode dataplates, VINs (Vehicle Identification Numbers), and production figures, etc. Knowledge of your own model is your best defense to keep from being ripped off. Nothing can take the place of original documentation such as Chevrolet Service News, Technical Service Bulletins, and original build records used to compile such books
as Chevrolet by the Numbers. Click here to find several suggestions on where to acquire reading material to acquaint yourself with Corvette model recognition.
There are many identification numbers that you can check on your particular Corvette. You must check them all to correctly verify that you have a numbers matching car. The total amount of I.D. numbers will vary from year to year.
The first and most obvious number to check is the VIN number, always found in the drivers' side door jam or on top of the dash panel. Depending upon what year of Corvette you are interested in, the VIN number and plate can tell you many things. When looking at a VIN, check the rivets or the tackweld attaching it to the body. Are they similar to other unrestored models like this car? Do the rivets show signs of age or do they look new? Does the tag itself look new? After you are satisfied the tag and rivets are original, copy down the VIN number to verify pertinent data concerning the car later. The VIN would typically specify the designated engine type, model series, model year, assembly plant, and sequence number. The VIN styles sometimes changed drastically from year to year so do your research.
Many secondary VIN numbers were stamped in various body locations on different body styles through the years. This was done to help law enforcement agencies identify stolen parts and/or cars. Once you start learning these secondary VIN locations, you can safely say you are becoming knowledgeable about your specific model. Many people who are now counterfeiting cars usually specialize in a specific model, so you have to become more knowledgeable to "balance the scales."
DATA PLATES
After the VIN number is validated, the next detail you should check is the data plate. The 1953-62 Corvettes had no data plate, while data plates for 1963-67 Corvettes are usually found under and behind the glovebox. On 1968-75 Corvettes the data plate is attached to the left-hand door pillar. The data plate contains information concerning the specific model, trim, assembly plant, paint code, and some option information. Also stamped is the body build date, which is very important in that all casting and stamping numbers on the car should precede the body build date. There are a few documented cases in which the drivetrain has been installed after the body build date, but this is rare. Many individuals are now reproducing data plates to validate incorrect cars. Option codes are also being added to some cars, which were not on them originally, to add unjust value to the car. Paint codes are even being changed to make the car more appealing with a higher resale value.
Another fallacy concerning matching numbers is the fact that if the engine stamping numbers correspond to the VIN, then the car is a matching numbers car. This is not correct. There are two specific stampings on an engine block beginning with the 1960 model year Corvettes. The first stamping is the engine assembly build date code, a stamping done at the engine assembly plant which contains the engine assembly plant designation, month/day date code, and the engine suffix code. The second code is the VIN designation stamping. We should note here that no Chevrolet engine was stamped with a VIN designation on the block prior to 1960. This stamping usually consisted of the vehicle VIN as well as the division (#1) and a model year designation. Remember, these VIN styles changed, so buyers beware.
Many final assembly plants used different styles of stamps to stamp VIN sequence numbers onto the block. Familiarize yourself with what type of stampings you are looking for. Most Corvette stampings have been verified and can be checked. Check all engine casting and stamping numbers as well. The engine has many external casting and stamping numbers to check, such as the block, cylinder heads, intake manifold, exhaust manifolds, distributor, carburetor, and so on. Also, be aware that there are many people who are providing original GM stamping equipment to restorers for the sole purpose of re-stamping blocks.
Another area to check for identification numbers is the transmission. Almost all transmissions have a build date code stamped onto them. This code can be stamped on a special boss or on a specified area of the transmission. Many transmissions are now being re-stamped. You should learn what size typeface and specific coding is correct for your model year and transmission type. Not all transmissions were stamped in the same area, with the position often changing from year to year. After 1968, a federal law took effect mandating that all engines and transmissions were to be stamped with the VIN, but many cars prior to this were stamped as well. Many VINs were stamped into the top of the transmission case or near the build date code. You should also look at the casting dates and numbers on the transmission. Make sure all casting dates match each other, such as the maincase, extension/tailhousing, and sidecover. Usually the date code consists of a numeric or alphanumeric code, which will resemble other standard casting codes found on the drivetrain of the car.
All casting dates for these components should be close to one another. In addition, the casting numbers should be correct for your car. Just because the build date code and VIN are on a particular transmission, it doesn't necessarily make it correct for your car. The rear axle also has a build date code, which will correspond to the actual build date of the body. This code, usually found on the center section/carrier or on the axle tube near the carrier, consists of a month/day build date, an axle assembly plant letter code, and a model usage suffix code. Almost all rear axles carry some type of date code on the cast part or center section of the axle, usually an alphanumeric date code as well. It is always a smart idea to compare this date code to the build date of the axle assembly, always remembering that the center section had to be manufactured prior to the axle being built.
The final area of matching numbers is paperwork. Broadcast sheets, build sheets, invoices, window stickers, bills of sale, and protect-o-plates are all being reproduced today. The main problem with this situation is that if there weren't people willing to spend "big" money to counterfeit cars, these people would not be in business. There are even people advertising that they can make the documents look old to replicate original documents. This is morally wrong and it is hurting the hobby. Many correct cars are being represented by forged documentation due to the rule of supply and demand. Unless you have documentation, original or not, chances are, in today's market, you won't sell your car for a fair price. This is a serious problem. Until you, the restorer, decide to police the hobby, things aren't going to change. It will become harder and harder to identify a correct car and eventually the value of many cars will drop.
On a concluding note, there are many Corvette owners who just like having a Corvette to drive and could care less about the whole matching numbers issue. That's great! The Corvette hobby should encompass all people, from the hard-core restorer to the everyday driver. A numbers-matching car can be very expensive to restore and maintain, much more so than the average driver car is. I say "to each his own" and enjoy the car no matter what it happens to be.CM.com
To say that this situation is creating a major problem in the Corvette hobby is a vast understatement. The problem lies in the fact that thousands of dollars are being invested into many "matching number" cars, which in fact are complete forgeries, built for the primary purpose of selling an incorrect car as a documented original. Many enthusiasts are unsure as to what composes a correct car. Much of the information that has been published to date in this area has been incorrect in several aspects. We want to clarify what is meant by "numbers matching" and how it pertains to you.
We should also take note of the fact that many cars suffered blown engines, transmissions, and rear axles in the musclecar era. Because the term "numbers matching" has been used so freely, many fine cars are now forged or faked to appear original for a decent resale value. Just remember that a car is only original once, which have been cleverly documented to be original "numbers matching" cars. There is a simple basic procedure to follow that will keep you from being burnt by buying a counterfeit Corvette.
Before we go into detail, let's interject a basic underlying principal: knowledge is the ultimate and only way to stop counterfeiting. Before you ever set out to acquire or restore a Corvette, become as informed as you can about the specific model you are interested in. There are literally hundreds of clubs for any year and model Corvette. Almost all have technical advisors and newsletters to help inform their members of new developments in the "numbers matching" area. Many provide services to help you decode dataplates, VINs (Vehicle Identification Numbers), and production figures, etc. Knowledge of your own model is your best defense to keep from being ripped off. Nothing can take the place of original documentation such as Chevrolet Service News, Technical Service Bulletins, and original build records used to compile such books
as Chevrolet by the Numbers. Click here to find several suggestions on where to acquire reading material to acquaint yourself with Corvette model recognition.
There are many identification numbers that you can check on your particular Corvette. You must check them all to correctly verify that you have a numbers matching car. The total amount of I.D. numbers will vary from year to year.
The first and most obvious number to check is the VIN number, always found in the drivers' side door jam or on top of the dash panel. Depending upon what year of Corvette you are interested in, the VIN number and plate can tell you many things. When looking at a VIN, check the rivets or the tackweld attaching it to the body. Are they similar to other unrestored models like this car? Do the rivets show signs of age or do they look new? Does the tag itself look new? After you are satisfied the tag and rivets are original, copy down the VIN number to verify pertinent data concerning the car later. The VIN would typically specify the designated engine type, model series, model year, assembly plant, and sequence number. The VIN styles sometimes changed drastically from year to year so do your research.
Many secondary VIN numbers were stamped in various body locations on different body styles through the years. This was done to help law enforcement agencies identify stolen parts and/or cars. Once you start learning these secondary VIN locations, you can safely say you are becoming knowledgeable about your specific model. Many people who are now counterfeiting cars usually specialize in a specific model, so you have to become more knowledgeable to "balance the scales."
DATA PLATES
After the VIN number is validated, the next detail you should check is the data plate. The 1953-62 Corvettes had no data plate, while data plates for 1963-67 Corvettes are usually found under and behind the glovebox. On 1968-75 Corvettes the data plate is attached to the left-hand door pillar. The data plate contains information concerning the specific model, trim, assembly plant, paint code, and some option information. Also stamped is the body build date, which is very important in that all casting and stamping numbers on the car should precede the body build date. There are a few documented cases in which the drivetrain has been installed after the body build date, but this is rare. Many individuals are now reproducing data plates to validate incorrect cars. Option codes are also being added to some cars, which were not on them originally, to add unjust value to the car. Paint codes are even being changed to make the car more appealing with a higher resale value.
Another fallacy concerning matching numbers is the fact that if the engine stamping numbers correspond to the VIN, then the car is a matching numbers car. This is not correct. There are two specific stampings on an engine block beginning with the 1960 model year Corvettes. The first stamping is the engine assembly build date code, a stamping done at the engine assembly plant which contains the engine assembly plant designation, month/day date code, and the engine suffix code. The second code is the VIN designation stamping. We should note here that no Chevrolet engine was stamped with a VIN designation on the block prior to 1960. This stamping usually consisted of the vehicle VIN as well as the division (#1) and a model year designation. Remember, these VIN styles changed, so buyers beware.
Many final assembly plants used different styles of stamps to stamp VIN sequence numbers onto the block. Familiarize yourself with what type of stampings you are looking for. Most Corvette stampings have been verified and can be checked. Check all engine casting and stamping numbers as well. The engine has many external casting and stamping numbers to check, such as the block, cylinder heads, intake manifold, exhaust manifolds, distributor, carburetor, and so on. Also, be aware that there are many people who are providing original GM stamping equipment to restorers for the sole purpose of re-stamping blocks.
Another area to check for identification numbers is the transmission. Almost all transmissions have a build date code stamped onto them. This code can be stamped on a special boss or on a specified area of the transmission. Many transmissions are now being re-stamped. You should learn what size typeface and specific coding is correct for your model year and transmission type. Not all transmissions were stamped in the same area, with the position often changing from year to year. After 1968, a federal law took effect mandating that all engines and transmissions were to be stamped with the VIN, but many cars prior to this were stamped as well. Many VINs were stamped into the top of the transmission case or near the build date code. You should also look at the casting dates and numbers on the transmission. Make sure all casting dates match each other, such as the maincase, extension/tailhousing, and sidecover. Usually the date code consists of a numeric or alphanumeric code, which will resemble other standard casting codes found on the drivetrain of the car.
All casting dates for these components should be close to one another. In addition, the casting numbers should be correct for your car. Just because the build date code and VIN are on a particular transmission, it doesn't necessarily make it correct for your car. The rear axle also has a build date code, which will correspond to the actual build date of the body. This code, usually found on the center section/carrier or on the axle tube near the carrier, consists of a month/day build date, an axle assembly plant letter code, and a model usage suffix code. Almost all rear axles carry some type of date code on the cast part or center section of the axle, usually an alphanumeric date code as well. It is always a smart idea to compare this date code to the build date of the axle assembly, always remembering that the center section had to be manufactured prior to the axle being built.
The final area of matching numbers is paperwork. Broadcast sheets, build sheets, invoices, window stickers, bills of sale, and protect-o-plates are all being reproduced today. The main problem with this situation is that if there weren't people willing to spend "big" money to counterfeit cars, these people would not be in business. There are even people advertising that they can make the documents look old to replicate original documents. This is morally wrong and it is hurting the hobby. Many correct cars are being represented by forged documentation due to the rule of supply and demand. Unless you have documentation, original or not, chances are, in today's market, you won't sell your car for a fair price. This is a serious problem. Until you, the restorer, decide to police the hobby, things aren't going to change. It will become harder and harder to identify a correct car and eventually the value of many cars will drop.
On a concluding note, there are many Corvette owners who just like having a Corvette to drive and could care less about the whole matching numbers issue. That's great! The Corvette hobby should encompass all people, from the hard-core restorer to the everyday driver. A numbers-matching car can be very expensive to restore and maintain, much more so than the average driver car is. I say "to each his own" and enjoy the car no matter what it happens to be.CM.com
05-14-2005, 11:53 PM
#7
Whew !! Interesting subject.I''ll be looking at a 68 427 4 speed tomorrow. The engine codes for 4 speed 427 engines are IM,IL,IR,and IT(L-88).They are IQ and IO for turbo hydramatics.
But engine casting numbers are 3916231 for 390,400,and 435 HP and L-88 engines.Clear as mud,huh ?
But engine casting numbers are 3916231 for 390,400,and 435 HP and L-88 engines.Clear as mud,huh ?
