will a 350 head from 1986 fit on a 305 block from 1986?

 

Yes it will question is will it give you the results you want ?

305s want heads with 55-58cc's and 350s have heads with 68-76cc's. If you put 350 heads on a 305 you may drop compression below acceptable values. Find out how many cc's the 350 heads are first.

RP.

 

I belive its of more benifit to put 305 heads on a 350? someone correct me ifim wrong

 

An '86 350 head should be 64cc. I'm not completely sure what they did with truck or full-size heads that year, though.

One benefit would be a larger intake valve - s/b 1.94" vs. 1.84" for the 305 heads. You should see improved flow, but there are "bad" 350 heads out there, too. It would be best to shave them down to 58cc chambers, which would require removing ~.04". If you do that, have the intake manifold shaved by the machine shop to match - prevents leaks.

305 heads on a 350 increase compression due to the smaller chambers. To really improve performance, though, they should be ported and the above-mentioned 1.94" intake valves installed.

 

only thing i know is both the 305 block is stock and so are the 350 heads the heads came from a Vette and the 305 is from a Z28 Camaro

 

I hear that the 350 vette heads (the cast iron ones) are 76cc. If so, you really dont want to use those on a 305. The aluminum ones you wont lose any compression, but they arent as good as the later aluminum vette heads.

As for bolting up, you can bolt up any SBC head to the block, only differences I can think of right now are the accessory bolt holes (or lack of) and intake bolt angles on the center 4 bolts. That and a 305 has a relatively small bore, which does not work well with large chambers and large valves. Could have issues with the valves hitting the block. All depends on what the heads are though as to if they will work or not.

 

If the heads are cast iron and came from an '86 Vette, they are 64cc.

If the heads are aluminum and came from an '86 Vette, they are 58cc. But, they're smaller to increase compression in order to compensate for the heat loss through the aluminum - on a 350.

So, either one should be shaved to maintain proper compression and power on a 305.