[Wayne 962]

In the book, I discuss following the guideline laid out by Walt Watson at Competition Engineering (1.25mm to 1.50mm or .050" to .060"). For higher performance engines where you have checked all of the clearances and can be assured of no conflicts, I recommend running 1mm or about .040". If you run it really tight on a mag case that has not been properly machined, then you might run into problems.

-Wayne