Head Information

kpack5982 said:

I've been learning new things constantly on here, but I still have some things to sort out. The one that is nagging on me right now is the cylinder heads. What is the difference between a 58cc and like 63cc or something. I read that 58 cc gives you a higher compression ratio, making power and mileage better, but how exactly does that work? what is the 58cc part that is measured, the cylinders themselves? And which heads can actually be placed on a stock block without having header and piston clearance problems? And finally, what is the difference between a valve angle job and what does it do?

Click to expand...

No matter which cc head you use you shouldn't have any HEADER TO PISTON clearance issues.lol

From my understanding: What is being measured (in cc's) is the quench pad area (where the valves are on the bottom of the head). Someone please correct me if i'm wrong here.

Piston to valve clearence is something that should always be checked and there is no "one size fits all" answer. There are many variables depending on cam size, rocker size, piston size, and valve size. Maybe even more. If you give a good description of what combo you are running then maybe one of the more knowledgeble people on here can give you a better answer as to what will work for you and what won't.

Matt

AFRs won't clear stock pistons with 2.02" intake valves, but Twisted Wedge heads with the 2.02s will. The TFS stage 1 cam will keep a good piston to valve clearance, but always check just to make sure.

The cc part comes in for compression ratios. Just before ignition, the top of the piston will be in line with the top of the block, making it flat. The combustion chamber (those 50 or 60 cubic centimeters) is where all the compressed air goes (a whole cylinder worth)..so when you have you are compressing a cylinder's worth of air into 58cc, it is more compressed than in a 64cc head.

Valve jobs are really just to clean up (or polish) the area where the valve rubs against the head..think of it like boring an engine oversized, but you're really just glazing it to clean it up, therefore giving you a smoother surface.

Hope this clears a few things up.