thopo57 said:
Because I know few about the C3's and american car in general, I would like to know how to check what a seller claims that the car he wants to sell is a matching nulmbers.
Is the VIN can check on the engine or not ?
What is diffence with the casting number ?
What is control of the date ?
What is control of the pad ?
If the casting number match, can you say that it is a matching number car ?
What happen when you put a NOS block engine in a 70'.
Thanks
Tom
Corvettes prior to 1972 had no engine information coded into the VIN number. To determine what engine type the car came with, you would need to either see the 'tank sticker' which will list all the options the car came with, or you could examine the car in detail to collect clues as to which engine it originally had. There are differences in tach redlines, radiator and shroud configurations, gas inlet lines, etc. etc, that are all clues.
The casting number is simply the basic part number (not serial number)that GM assigned to a block when manufactured, before machining. This number by itself proves very little as GM may have used the same casting number on many other types of cars, not just Corvettes. Having said that, there is information available as to which casting number your Corvette should have. If the casting number is 'wrong' then that is a very good indicator that it is not the original engine.
The casting date indicates the calender date when the block was cast at the factory. This date must always precede the car assembly date, typically from just a few days up to 6 months (which would be unusual).
The stamp pad indicates two things. There a two separate stampings made, one at the engine assembly plant, the other at the car assembly plant
One stamp will be in larger font and will start with V or T to indicate which plant manufactured the engine. V is Flint, which did all of the small block engines, T is Tonowanda which did the big block engines. This will be followed by four digits, which indicate which month and which day of the month the engine was assembled. December 5th will be stamped 1205, for example. This date must also precede the assembly date of the car, but be subsequent to the casting date mentioned above. The last two or three characters of the stamping will be alphabetic, and is the engine code which indicates what type of engine it is. Corvettes prior to 1970 have a two letter code, 1970 and up have three letters. Code 'CTL' on a 1970 means 350 cu in, 300 Hp, Qjet carburetor, 4 speed transmission for instance. This code must match up with the configuration of your car.
The other stamp on the pad was assigned once the engine was installed in the car, and shows a derivitive of the car's VIN.
Underlying both stamps should be traces of the original machining marks from when GM 'broached' the cylinder head mating surface. These should be appear as a series of parallel lines running from front to back on the pad.
If you find deviations from any of the above, be suspicious.
If you can get some good close up pictures of the pad, post them here to let people have a look.
The term 'matching numbers' is too vague and ambiguous to say when you can or can't use it. Usually the seller of a car claims that EVERYTHING as matching numbers without having a clue what numbers he's talkng about.
If only the casting number 'matched' but you knew that the same casting number was also used by GM for engines that went into garbage trucks, low powered family station wagons, industrial power generators, etc would you think it honest to say that it was still matching numbers? The 3970010 block from 1970 on up was made by the millions and got installed in just about every V8 powered car GM made.
Buyer beware.
If the seller has a NOS block, it's not the original block so it's still an NOM car in my mind.
Hope this helps
