I have the chance to pick up a whole engine and tranny (the tranny i'm deffenetly getting it's a T400HD that's in way better shape than mine).

the block casting number is: 3970010 which comes out to be a 1974 350 L65 or a 307 or a 327 (got love the GM casting system)

the heads are: 3998991, which are 307 or 350 heads with 75cc chambers made from 1972-1973


I have 882's on my 355 right now which are known to be crap but anyone think theese heads are better ?

i was thinking about just buying the whole engine and building it up to swap out with my 355 but i dunno yet...

here is a pic of the casting mark on the side of the heads:




Thanks for any info...


Dave

 

The heads are crap. 2-barrel heads. Throw them away.

The block is a block. 4" bore. Since all of those motors are 4" bore, it could have originally been any of them. Odds are quite hich that it's a 350 though.

The third size is 302, not 307. The 307 had a 3.25" stroke and a 3.875" bore, and therefore couln't be built out of that block.

010 casting was used from 69 to about 78 or 79. You can't tell that it's a 74 or what RPO the motor was by that number. It could have been any number of RPO codes, depending on whether it was a 2-barrel, a 4-barrel, a truck motor, car motor; L48, LM1, L82, LT1, etc. etc. etc.

 

good info,

everything i found was in these pages:

http://www.jimsperformance.com/blocks.html
http://www.chuckschevytruckpages.com/casting.html
http://www.mortec.com/castnum.htm


it's funny how all the different sites have everything different.... Kinda makes you wonder...


the dude with that engine said that it came out of a '79 stepside Chevy and it was a 350. i saw the head marks and decided to do some research. it's got a quadrajunk on it so somebody must have swapped the heads at some point.......

 

Yeah, gives new meaning to "I saw it on the Internet, it must be true!!! You can't post anything that's wrong, can you? CAN YOU????!?!?!?"

But to be completely honest with you, I don't have to depend on Internet sites for everything, since I've seen a set or 2 of about every SBC head there is at one time or another; especially the ones that were common on vehicles in the late 60s and the 70s.

Head swaps are real common. People have a problem with their vehicle, take it to the shop or disassemble it themselves, find a blown head gasket or whatever; decide the thing to do is to get a replacement set of heads. After all, they can walk into the shop and get a set of "350 heads" for $275 a pair or whatever..... so they unknowingly drop off a set of groaty disgusting 186s off of their 69 Impala 350 4-barrel with cork valve cover gaskets that turned to dust 50,000 miles ago, and walk out with a brand-new-looking shiny set of 624s off of a 74 Chevelle, and think they got a deal. Then they can't quite figure out why their car doesn't run anywhere near as good as it did when it was new; and they blame "rebuilt" stuff as the cause. Little do they know that if they had gone the other way (took 882s off of their 74 Monte Carlo 400 for example and put on 186s), their car would have got an immediate 25% or more bosst in power.

So, 25 or 30 years after the fact, you and I stumble across a 69 Impala 4-barrel in the junkyard, and out eyes light up; until we realize that the heads are garbage. But they look like they've always been there. How can this be? Now you know.

Unscrupulous machine shops used to make alot of money off of people like that.

 

hey check out www.nastyz28.com they have a more accurate listing of the casting numbers i believe than a some of the sites on the net still not 100% accurate thou..lol

 

They have an accurate isting of what came on '70-81 Camaros, yes. Well, the good ones, like the SS and Z28 anyway, not really for the lesser 350s and 307s, etc.