SBC Heads

I've got a set of heads that have a sort of camel hump to them but they are squared off on the tops and the 3 digit casting number on the bottom under the intake side is 434

I tried looking them up but came to deadends in regards to them numbers, looks like the big 194 intake valves though with the small combustion chambers (as in level with where the spark plug threads come into the chamber) they got 3 accessory holes drilled into them so I know they aren't real ancient

gonna sit down to a thanksgiving feast shortly but I'll try and get some pictures before dark

thanks

 

<font color="green">The casting numbers you are looking for are on the top, in between the valves.

I can't remember how many digits either.

Go here Mortec and you will find all you ever needed to know about Chevy casting numbers. </font>

 

6 digit number (354434) saids they are off a 262 or 305 vintage 1975/76

they needed rebuilding anyways so back in the corner they go

 

Guys thing to remember. When running 305 heads on a 350 or other SBC causes a comp.ratio INCREASE because of the smaller combustion chamber ( I think they are 56 cc ) it will knock and ping like hell with pump gas!

 

I put stock rebuilt 305 heads on my 283 because they were cheap - 150 bucks each and I needed the small 58 CC chamber.

I think they are going to be a good head on a 283. Has anyone had any experience with this combo? It is going to be a while before I crank this motor up to find out myself.

 

whats the highest compression ratio thats safe to use on say 90 octane fuel?

 

10-1 compression

 

The compression ratio being too high depends on the pistons too.... Chevy made some REALLY LOW compression motors in the 70's... the 305 heads (although they have **** for flow numbers) may be a good way to pick up some compression for increased performance.

A smaller chamber is ALWAYS a better way to gain compression than a larger piston dome...

I also agree, with iron heads, I'd try to stay around 9.5:1 or 10:1 tops.

With aluminum heads, and a big cam I run almost 12:1 (11.7:1) on pump premium (94 octane), without the slightest hint of detonation.

 

I have a 283 with 305 heads and it is the sweetest little motor I have built. Not balanced but sooooo smooooth.
Don

 

Did chevrolet ever make an alunimun, amilun,,,aluminum 305 head? I'd like to run a pair on my 283 with flatops if they're in existance. I suppose they'd have that silly manifold bolt angle the late engines use?

 

they did make a small chamber aluminum "corvette" head. I see them brand new at swap meets all the time, but for the money, I think I'd rather go aftermarket!