how big of valve can you cut into a 194 fastburn head ?

Answer 1

never heard of a fastburn head , if you are talking about a small block Chev. 1.94 inch diameter intake valve head , you can go a few thou. over but there is a danger of recessing the seat and that will rob power. if you need a bigger valve go with a 2.02 head , there is no shortage of buyers for an unmolested 1.94 , good luck