I started porting out my 311 101 373 A single port head and was pretty happy with my just smoothing it out, I thought I did a good job and was happy enough to make the second one match. The second one is a 040 101 373 2 and has larger passages than the 311 head after cleaning it up. Are the 040 heads the single ports with the largest passages? I don't know if I have the patience right now or the tools, but are the 311's just that much thicker so they can be ported out to match the 040's? Or did they redo the mold with the 040's and make the passages larger with the new mold?
I figure someone has to be a single port motor fan or maybe a score racer that has experience with the single port heads and performance.
Thanks
TIm