alright someone please explain the theory of heads on the engine seems none of my friends can or any mechanics around. Was wondering why people use 64 and 76cc heads on a 350 when Ive been told that 58cc heads would boost compression to 10 to 1. Good for performance right? yet my 305 has 58cc heads on it stock, so what would happen if I put my 305 heads (stock for now ported later) or performance or rebuilt 305 heads on a 350 bored 30 over and an upgraded cam? thanks so much for clearing up my confusion.

Jason

 

people go with a smaller CC head for more compression you don't want a head with a monster chamber on a large bore motor either..

 

305 heads might help an 8-1 small cam smogger motor. At some point the small valves in a 305 head along with the small ports will become a restriction.
A bigger chamber will usually out flow a smaller chamber due to valve shrouding.

So a stock low cr motor would pick up some 1-4k power. And some gas mileage. Not a bad idea for that set up. But few people run such a small cam for long w/ perf. in mind.
Usually only done when "free" or "out of cash" is involved.

 

definitely out of cash but can get a short block with a cam in it pretty cheap, but all in all the stock 305 heads on a 350 will run alot better than a slightly modded 305 right? thanks

 

You'd be better off with the stock TPI heads and using a thinner head gasket to boost compression. You want the bigger ports and valves so you can get upper RPM power. The reason people run the larger chambers is so that they can run larger valves. The larger chamber unshrouds the valve and allows better flow. Also too small a chamber could cause other problems with flame front travel, but that's a whole other story. Stick with the 350 tpi heads and use a thinner gasket for more CR. But you're going to have to run better gas.

 

I agree