Originally Posted by
racingrick
I've done it also, used chevy valves and "backcut" them them on a grinder, but I did do it with the motor on a stand. I know a guy in lakeland that has done it in car a few times using old chevy valves (and yes, use stock heads for the guide). It's really easy to go too far they cut far easier than you would think.
I used painters tape on the valve stem and marked out .010 increments to know how much needed to be removed. As its going down the tape will destroy itself from spinning contact in the valve guide.
And like you said,.. they eat into a piston like butter. Dont push too hard or for too long. It happens faster then you might think.
Porting aluminum heads is pretty much the same. Dremel has these bits with teeth on them and they chew through the aluminum like butter with out getting clogged up like grinding bits do.
Hurst