Cast # 3998920 which equals 72-74 w/ 1.94
My question is, what are they from??? Other numbers on heads state: GM1 and also L-09 2
Hope this helps, and if it doesn't help, how can I find out what the engine is from.

 

I can't really help much here. However, there have only been a handful of heads produced there were ONLY for one vehicle, or even platform. Like 882's.. they came on just about everything w/ 8 cylinders in the 70's... you could have them on trucks, station wagons, chevelles, novas.. the list goes on.

 

My info says the 920 heads came on 350s from 1972-1975.

The L 09 2 casting date works out to December 9, 1972.

Please Note-I have read somewhere (a long time ago) that the letter code for "I" was not used by GM because it could easily be confused with "1".

If that is the case, your heads would have been cast November 9, 1972.
jms

[This message has been edited by jms (edited June 20, 2001).]

 

There is now way to determine what the heads were originally on. GM never put suffix codes on the heads. Only on the blocks.

 

Where can I find the suffix code on the block????

 

What is it you really want to know about this motor? Maybe you can attack the issue some other way besides finding out "what the engine is from", and get some actually useful information instead of that, which would be pretty much useless. Knowing what shape and size of sheet metal it was originally wrapped in will tell you very little of anything useful. No magic is mystically left over in the cast iron from the old chassis, even if it was from the legendary Vette that about half of all the motors in existence came from.

That head casting is the low-perf version of 350 heads, it also is listed for the 307s of the day. That means they came in 2-barrel applications. 1.94 valves AFAIK are the stock size in virtually all, if not all, 350 heads, so there's no distinction there. It is a large chamber head with small ports and big valve guide bosses, especially on the exhaust side. Not suitable for any sort of performance usage. If the block is in fact a 350 block and not a 307, then it's just taht: a 350. They're all pretty much equivalent for most of what the majority of us on this BBS are likely to use one for.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

The block suffix code will be on the little tab surface in front of the passenger side head (behind the alternator). The codes are stamped into the block and are usually hard to read from dirt and paint. If the block has ever been decked then the codes are gone.