I was working on a 350 for my camaro, but that didn't work out.. the block and crank were no good. But, the heads were good, so I gave them to the machinist to redo and port. I figured I'd freshen up the 305, put a cam in, and throw these ported 350 heads on.

But, I just talked to him, and he said the 350 heads won't work on a 305 cause the bore is smaller on the 305 and the valves in the 350 head are too big for the 305 bore.

So.. am I screwed for using these 350 heads on my 305? I dont remember ever hearing of a problem of swapping heads between a 305 and 350.


------------------
Luke
94 Saturn SL (1.9L)
86 Camaro Berlinetta (5.0L) *TPI 350 In Progress*
Berlinetta Board Mod @3rdgen.org


[This message has been edited by sven86berlinetta (edited April 04, 2001).]

 

I can't say it's true for all chevy heads, but Mike Gillen is running L31 Vortec heads on his 305, with no problems. Those are 1.94 1.60 valves in a 64cc chamber, so I'll assume the chamber width is typical of most SBC heads. Now if you put some 76cc smog heads on there, I couldn't say.

[This message has been edited by Macgyver (edited April 04, 2001).]

 

It depends on the valve size and location in the head. I personally have never heard of anybody using heads on a 305 with valves larger than 1.94 intake and 1.50 exhaust. Anything larger and you run into valve-to-bore interference. However, some heads with larger valves can be used on 305 heads, assuming your cam doesn't have too much lift. If you'll check Edelbrock's web site, they say their Performer heads will fit on 305s as long as the cam has less than .450" of lift.

Another thing to consider is the combustion chamber volume. Our heads are around 58 cc and the compression ratio is about 9.3:1. A 64 cc head will drop that compression ratio down to around 8.6:1. The loss of compression results in less than optimal power output, but assuming the heads flow that much better you may actually experience a gain. This is supposedly true with the Vortecs. They have 64cc chambers but make much more power than the stock 305 heads.

If you do have the 1.94x1.50 valves, you could always install them, throw some clay on top of the pistons and slowly rotate the engine by hand. If you do it slowly enough you'll know if the valves hit the bore or pistons and you'll be able to check valve-to-piston clearance with the clay.

Your machine shop should know this stuff. I hope this helps you out,

Jason

 

Yea some work and some dont. I was told by a machinist that they might not work for valve clearance and they might leak water in.
dunno just what he told me. just check everthing out pull some numbers off the heads
and block take them to your machinist see if they can be used togather.