Eng Block Identification
 

Afternoon gang
Need some help. I’m getting ready to rebuild a Chevy Block. The GM code shows a 3914678 eng stamp code, but when I look it up, I find it can either be a 302, 327 or 350. There is another stamp that looks like a VIN number that reads: 18J102400VOI84HM. Can anyone help me decipher this? I’ve researched it and get conflicting answers. Any help will be appreciated!!!

Re: Eng Block Identification
 

It will come down to the casting date on this engine suffix. If it is 1965 or 1968 it is a 327, if it is a 1969 casting it is a 350

Re: Eng Block Identification
 

Thanks SStock

Here is what I found and what my dilemma is in trying to glean the info from the internet. Here is what I found. The casting numbers are the same. I could always measure the stroke, but was trying to save myself some time. I’ve already removed the pistons/crank.

Re: Eng Block Identification
 

You are going by the engine casting number, I'm going by the suffix which is HM, which further breaks it down to a 327 if it was indeed casted in 1968

Re: Eng Block Identification
 

If it is the 302 and the car is still around, someone would pay handsomely for that, 68 302's are very scarce.

Re: Eng Block Identification
 

HM engines in 1968 and 69 were 250 hp engines and chevrolet made a kagillion of those., a 302 would have a DZ suffix and now yes you are right good money in one of those.

Re: Eng Block Identification
 

Yes that casting number puts it in the 4" bore family, the difference only is the crank/rods that got dropped into it. 302 had a 3" stoke, 327 had a 3.25" stroke and 350 had the 3.48 stroke cranks. HM tells you the actual engine application 250 hp 327 or 350 cu inch

Re: Eng Block Identification
 

they didn't make a 350 with small journal crankshaft did they?

Re: Eng Block Identification
 

I'm pretty sure they didn't... :ito:

Re: Eng Block Identification
 

Hello, im into tracing chevy numbers. What is your crankshaft casting #? Also post a pic of the different numbers cast into the front block face. I wasnt able to get much yet with the stamped # on the cyl head deck(18J)

Re: Eng Block Identification
 

thanks RideBlue...I’ll dig into it tomorrow. I really want to nail this down.

Many thanks