I have a 1974 Corvette L82 it is a 350cid 250hp with M21 tranny. My issue is the engine stamp code RAI 1347 tells me nothing online it is also a 3970010 Casting. Please help with info anyone. Thanks

 

The 3970010 casting number was used on 350 Chevy car, truck and Corvette applications (both 2-bolt and 4-bolt mains) from 1969 through 1979. You should check the casting date next to the casting number.

You need to look closer at your stamp pad. The code you have listed is only partially complete. In smaller stamps, the stamping should start with the year of the engine production (in your case a "4") followed by 6 digits of the VIN number that the engine was installed in. The VIN number may have the vehicle assembly plant code in front of it. Sometimes, there is a "1" before the year number, signifying "Chevy." After that, in bigger letters, comes a single letter designating the assembly plant of the engine:

F= Flint
H= Hydramatic
K= St. Catherines
M= Mexico
S= Saginaw
T= Tonawanda
V= Flint

After that is the engine assembly date code for the month and day of assembly, finally followed by a 2-letter or 3-letter engine ID code.

Thus, if you uncover the entire stamping on your stamp pad, the engine ID could look like this:

14S122891 F0518CLR (or YF5)

Where "1" is Chevy (sometimes not used), "4" is 1974, "S" is the St Louis Assembly Plant, 122891 is your VIN, "F" means the engine was assembled in Flint, 0518 means it was assembled on May 18th, and "CLR" is a 250 horse 350 Vette with manual tranny (as was YF5). The casting date should precede the assembly date by a month or more.

If all these numbers are not there, the block has either been decked, or it is a service replacement block.

Here is a photo of a typical small block stamped block:


From the above description, you can see that this is a this is a Chevy (1) 1973 model year (3) built in Norwood Ohio (N). So this is not from a Corvette. 132794 is the unique vehicle serial number (to match against vehicle VIN). V0112 (Flint engine assembly plant, January 12th). CLJ in 1973 is a 245 horsepower 350 used in a Z28 Camaro mated to a manual transmission.

Your Vette block should have a very similar stamping.

Lars

 

The RAI 1347 is all that is there. I have checked it over and over that's why I am stuck with finding info. Is the RAI 1347 use less ? Thanks

 

Possibly, unless we can determine what RAI stands for. I'm guessing it's a rebuilder's mark. It is not a factory stamp.

 

If the factory stampings are not on the block, the block has probably been decked, and the machine shop doing the work put their ID and job number on the block instead. It doesn't make the block useless - it just doesn't have the value of a correct, "numbers" engine any longer.

Lars

 

That was my guess.

 

It's going up For Sale as I only wanted to restore it if it was Matching #'s . It is a 4-Speed and less than 3500 were made as well as it is a L82. Engine sounds good but it would be a major restoration or great donor car.

 

I don't know if this applies to small blocks, but when restoring a 69 super sport Chevelle, no markings were on the original engine pad, other than the engine suffix code. The engine had never been decked or rebuilt.
After a tip from another fellow enthusiast, I found the Vin was stamped on the housing next to the oil filter.