5-0 Blackbird

Hey guys, starting looking more into any ID numbers I can find on this 350 motor I pulled from my bird seeing as though I don't know much about it and it now needs some internal work. Anyways, the block is a 010 70's 350 from a truck/ van of some sort, but when I went to run the ID for the heads I got a casting # of 3973493. Now I looked the number up on Mortec and it says:
3973493....71-72...400..........76cc chamber

Now, I'm not familiar with these heads at all so I was wondering if while the engine's out and being fixed, are these heads worth leaving on for now until I can get some Vortec's or something, or are they really killing the engine? I'm on a pretty tight budget so if they're not too bad, I'll leave em alone for now, although I would rather fix any performance hindering parts now while I'm going through the motor so I don't have to do something twice. I haven't got too much into the engine yet, but I was also wondering if maybe the person who built the engine may have been running some high compression and used the bigger chambers to drop it a bit? Idk, just a thought, I'll find out when the heads actually come off. Thanks for any help though!!

tony_cogliandro

iTrader: (3)

dont know what they are on but they are for a sb 400 ci engine and they are 76cc.
clean them up and have fun.
they were also used on a 350 and if they have steam holes they can go on a 400 but if not then they will run pretty good on a 350.
it was a way that gm reduced compression to get under the smog laws.
try looking here http://books.google.com/books?id=78T...num=7#PPA55,M1

AlkyIROC

With an 010 casting block, you know it's a 4" bore and probably a 350. The heads however are not original. They were originally on a 400 SBC. There's nothing special about the heads. They're typical smog heads with small valves. They probably have steam holes in them for the 400 block.

Providing they're not cracked, they'll do fine for a stock replacement engine build. If you're planning on doing any kind of buildup, buy something better.

5-0 Blackbird

Alright, I'll probably just leave them alone for now assuming that when they're checked they're ok. And for Tony, it's a 1969-79/80 350 out of a truck supposedly rebuilt about 10,000 miles ago and when I took the oil pan off found out it's a 2 bolt main. Anyways, I was stripping the motor of unneeded parts so I can get ready to take it to the machine shop, when I came to removing the manifolds. I noticed that the passenger side manifold didn't have the last bolt (closest to the back). There wasn't even a hole for the bolt. I'm assuming this is normal for these heads?, but will normal third gen headers work fine then? Or will the exhaust ports not line up? If this is gonna cause any probs as far as fitment or gaskets when I install headers, I'd rather just replace em now. Thanks for the replies so far though!!! Hopefully I'll have it up and running again soon.