Hello Everyone,

I just got a 68 Firebird with a 455 engine block, many numbers on it and I have no idea what most are, I have deciphered some.

Can anyone help me find out where this block came from?

D151 and a 7 and 71 on top which I found out it was build in April 15,1971.

455 is stamped on the engine side.

Other numbers:

C372079 and YC (which means automatic trans) I guess? What are the first numbers?

485428 means 455 HO in late 1971?

A very light tamping 21376313 (not sure since it is VERY light), what are these?

 

Can anyone help in what the numbers mean?

 

Best regards

Joey

Just wanted to drop in and say

 

I do not have any answers for this but I'm sure one of our elder Pontiac geniuses will be able to tell you.

the D code, as you found out is the date code. The YC is auto. the C code is the assembly location, California. the 2 code is the block VIN. hopefully i got that right, the actual pros will show up later and answer your questions.  

21376313 is the VIN that the block was originally attached to.

 

Not sure what the C372079 but Frosty is a whole lot smarter than I and he should chime in here.

Sorry I am on vacation so I am not checking in as often as I should.

D151 is the build/cast date of the block. April 15, 1971. A=January,etc.

Yes 485428 is the casting number of a 455, but this casting was used from 71 to 74.

YC would indicate an automatic transmission (a Th400) for either an A, B, Or F body car in 71.

C372079 is the engine unit number. It has no correlation to the VIN. What I have read, the "C" is really a chipped zero on the dye. So the engine or motor unit number is really 0372079.

Like the man done said:

D151 = April 15, 1971 - which means it's for the 1971 model year. The engine foundry generally would start casting blocks and parts for the next model year in about June, so an F or G code (thereabouts) would have indicated model year 1972.

485428 = 455, add the YC stamping tells you it would have been used in an automatic transmission car and would have had the 067 cam, 4 barrel, 66 casting heads, nominal 8.2:1 compression ratio, and rated at 325 HP (highest HP rating for any of the 1971 455's).

That 21376313 stamping, if you found it down low on the front of the block, next to the timing cover, would be the last digits of the VIN for the car the engine is from.

Does it have 4-bolt main caps?

 

Bear