What are the advantages/disadvantages to milling heads on an angle?
Anyone know?

 

It's usually used by the stock car guys to up the compression on a SBC. It reduces the size of the combustion chamber.

 

Yes, and we are building a stock car engine, but I'm not sure if a bigger angle is better or not. Say 11 vs 18 degrees.

 

I will also affect your PTV clearances.

 

It allows you to get the same if not smaller chamber size without removing as much material from the center of the head. So as long as you cut the intake surface of the head to match what you have angle milled the intake angle will remain stock.

 

Yeap..

 

If you are going to do it, reduce the angle, It should aid and low and high lift flow just slightly if you reduce the angle as the valve will be going straighter down the bore. Like everyone said though it is to get the compression down significantly. Just make sure not to go to far overboard or everything on the head is going to have to be modified (rocker locations, intake location, etc.).