Source for 6 cylinder codes?

[Tom Kochtanek]

What is a good online source for decoding the Chevy 6 cylinder engines?

I've got what appears to be a 50s Chevy six cylinder engine, probably a 235 cubic incher, with a block casting of "3837004" and a date code which reads "266".

I'm going to guess that it's a February 6, 1956 235 cubic inch six cylinder, but I'd like to verify that. Anything special about it (like being a "Blue Flame six)?

Thanks in advance for your help!

Best,
TomK

 

[oldskydog]

Tom,
I don't do 6 cyl very often but recently I decoded my son's 51 engine and it might take me a while but I can probably find it. I'm sure there is a stovebolt lovers site out there. Just going by the casting number that looks more like a 60's part number. Does it have a suffix code?

 

[CDNpontiac409guy]

Tom, I'm embarassed to reveal that I might know ANYTHING about these things:
One pattern that I have noticed is, with few exceptions, on ANY Chevy castings that begin with 383****, the part will not be older than about 1961.
Which, if this is true, the engine is a 61 or 62 235 or 261.
Are you sure that 'it's a "big block" 6 ?

I have a 1961 261 on the floor. I'll check the casting number tomorrow.

 

[oldskydog]

OK, here it is, you were right:
T56X 55-57 chev 235-261

http://clubs.hemmings.com/clubsites/chevytalk/GMhistory/index2.html

:

 

[CDNpontiac409guy]

And THAT blows my theory out of the water
NEVER ever saw that before

Best I stay away from the 6's

 

[Tom Kochtanek]

Suffix #s

Cecil and CPG, thanks for your help and info. Looks like it is correct for the 1957 model. Not sure where the suffix numbers are on a six cylinder block.

I should stick to the stuff I know as well. Rather it be a "W" than a commn I6 or ordinary V8 .

Cheers!
Tom