I just bought this car 1990 Firebird, looks like your standard 305 tbi motor with a busted oil pan.

Well, I go to replace the oil pan, and it's not the right one!
so I got all the casting nad serial numbers hoping someone here could tell me what I've got.

Casting: 3970010 K10
serial# 141648171
K01 09 CMR


So far I found out that it was built on St Catherines's Ontario
Jan 09 and the CMR means that it's either a 74 or 78 350 or a 1980 305 How can I find out if it is the 305 or the 350?

Thanks for the help!

edit, Got the crank cast # 3932442

Pretty sure now that it is a 350!

 

It's a 350. That is indicated by the casting number (3970010).

Beyond that, it's anybody's guess. It has probably been rebuilt more than once, and bears little or no resemblance to whatever that serial # would tell you. No telling what pistons are in it, what heads are on it, what cam is in it, etc.

 

That was weird....

442 crank castings also came in most 85-back 305s. The stroke of a 305 and a 350 are the same. The bore is different, so the block casting will tell you for sure which one it is.

 

http://www.mortec.com/castnum.htm

This might help you..it confused the hell out of me!

 

Yep, but you can quickly tell the difference in counterweights. On a 305 crank, you can lay a straight edge down and rest on all the weights. On a 350, the weights are larger and that won't be possible.

Using a 305 crank in a 350 might cause some interesting vibes.


-- Joe

 

It's official,
it's a 350, after sleeping on it, I put 2 and 2 together,
the 3970010 casting on the block meast that itis a 4" bore,
whick makes it a 302, 327 or 350, add the crank 3932442, a 3.48 stroke and, ta da, it's a 350.

Thanks for your help!