hey guys, i've always had trouble in this part of the build, as far as trying to find some mild performance heads for my car, i know the sizes of the valves don't matter with performance but the size of the combustion chambers do, now, is it the lower number combustion chamber size the better or the other way around, and since the valves don't matter, how come there is diffent sizes of valves in every type of different heads, (for ex. 2.02 and so on and so forth), but if someone can answer that question on the cc's and the valve sizes that would be great.

 

In general the lower cc number on the combustion chamber is better partly because it can raise compression and partly because it offers a more effecient environment for the combustion to occur. Valve size does matter or you wouldnt see heads with bigger valves. You must keep in mind though the head needs to be designed or ported for bigger valves to work properly. Say if you took a stock vortec head the intake is sized 1.94 if you would change the valve to 2.02 you could actually show no gain or lose flow due to the valve shrouding and chamber design, if you took that head to a good head porter the larger valve would show a gain. When you really start looking at heads it can get very confusing flow velocity, swirl, cylinder filling, quench distances, plug locations, runner design.Everything should tie together to make it work well for your combination and for what fuel you want to use. In my opinion one of the best heads out there are the afr heads but they are a bit pricey. For a mild engine one of the cheaper options is the vortec head they have an excellant chamber design and flow better than any factory production gm smallblock head. We are running a vortec headed 350 cast piston factory crank, unbalanced .420/.440 lift summit hydraulic cam first time out with this cam it ran a 8.44 in the 1/8th it has the potential to run in the 8.30 range with some tuning, this engine only has about $700 in it. http://s99.photobucket.com/albums/l3...t=ba97afd4.pbr