I know alot of people talk about putting 350 heads on a 305. But the compression would be less, so then, couldn't u put 305 heads on 350, and maybe port them out or whatever so they flow better? then wouldn't that Raise compression? i know this is a crazy question, but i haven't seen it asked before,

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

This is an easy way to increase compression. Be careful, because it might be too much. I thought about doing just that with my 350 or 383 buildup, but too many people told me no, don't do it. But I speak to others who have done it and had no problems. Its a risk, but you will definately have to run premium fuel.

John

 

You could, but the heads will need to be extensively ported by someone knowledgeable. If you go the route of bigger valves, you get to work the combustion chamber as well to unshroud the valves, which will help to negate the compression increase since you will lose a fair amount of material from the chamber.

 

how much more power do ya think someone would get doing this

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

More? I'd say none, if not less. You'd have to put more money into the 305 heads than they are worth unless you happen to know what you are doing and have a bunch of spare equipment laying around. The compression increase isnt worth the effort to swap heads.

 

I have my original 305 heads on my 350. as far as the porting mine are and if you take the center bolt 305 head and put it next to a center bolt 350 head the only real noticable differanc are the valves and even those are real close. I had the 1.94 valves installed in the heads as well. now for the power yes they are way better than a set of "stock L98 heads" but, if you don't know any one at a machine shop than or your self than for get it. the L98 heads are a dim a dozen. and for the money you could get better heads. the compresstion is not as high as every one tries to say it is..(.5 I think? I for got but going from 9.5 to 10.0 is not any thing at all. I have ran 87 oct. with no nock and had my timming advanced. yes I even watched with a scanner! I make lots of low end torque but, thats mostly due to the cam I have.

 

I will be putting modified 305 heads on a 350 in a few weeks. Mine are basically copies of World Products torquers with a little more porting done. I hope they at least perform better than stock 350 heads.I couldn't afford to buy another set for the 350.