Thread: chevy 327 ID Stamp

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I just picked up a 66 327 and I'm having a heck of a time identifying the stamp on the front of the block.


Block date code on the back reads:
D256 = April, 25th 1966
Block number reads:
3858174 = 64-67 327
The stamp reads:
F05O4_C

I gather that the F= Flint, the 05 = May and the O4 which should be a 04 = the 4th day of May.

The suffix is what I'm not clear on. The only thing close that I have found is EC but it really looks like and underscore and not an E before the C on the stamp. All the numbers and letters are clear to view also.

I have been to the "nastyz28" website and looked through all the codes, like I say, only to find maybe "EC" for the suffix.

Any ideas? Does someone know if they only produce certain blocks on certain days, April, 25th 1966 etc... or only built certain cars on May 4th 1966?

Any help would be greatly appreciated.

all single letter "C" blocks were either 265s or 283s. There was no IC code used for any size. There was an LC but it was a 265.

The "lowest" letter code for a 327 was a "R". Only single letter codes for 327s were R, S, and U.

There were NO 327 engine codes that were two letter starting with a C so that rules out those combos.

There is the EC code for 1965 and 1966.

In my book, the 3858174 casting shows 1965 and 1966 327 engines with 275, 300, and 350 horsepower and 2 bolt mains (of course).

Thanks for the quick response Robot. I am going to go home today and see if I can clean it a little better with solvent to see if that reveals the stamp a little better. I am also going to pull the pan and check the crank number.

I will keep you posted on the outcome.

Well the crank is a forged 327. The stamp is exactly the same after being cleaned with solvent. I would guess that it is a 275hp, A.I.R., chevelle motor.

It will work great in my '65 GMC 1/2t 4x4.

Thanks for your help robot.

Hi I'm new bee here. I have 327 SBC I was told at the time when I bought it came out of a 65 corvette. Can you help me with the numbers off the block and tell me what they mean. 3858180 A266, these number are on the front of the block behind the timing cover - T4 ONVI it could 0NV1 to.

Thanks if you can help.

Originally Posted by jag327

Hi I'm new bee here. I have 327 SBC I was told at the time when I bought it came out of a 65 corvette. Can you help me with the numbers off the block and tell me what they mean. 3858180 A266, these number are on the front of the block behind the timing cover - T4 ONVI it could 0NV1 to.

Thanks if you can help.

That be a 64-67 327 according to the casting number .....
This link is pretty good for most numbers http://www.chevymania.com/partsid/

click on the left under "suffix code" for the exact application

3858180 is a casting number for the 64-67 327 block and can be anywhere from 250 horsepower thru 375 horsepower....so that part is fine with the claim that it is a 65 Corvette block

Your code on the block pad (passenger side, just in front of cylinder head) doesnt make sense....there were 19 suffix codes for Corvettes in 1965: HO HQ HE HI HP HR HF HJ HT HU KC HV
HW HH HK HL HG HM HN

Note that all but one start with the letter H and are of two letters.

mike in tucson