hello, sorry in advance if its been already asked. but I am building an a12 up with a hotter cam for higher rpm and torque. so far I have arp head and conrod studs, 74mm bore, 278 cam, dual valve springs, 34mm bs34 bike carbs.

now my question is dose a h10 head fitted with L16 valves(38/33), ported and polished, and possibly raised ports(depending on cost) flow more than an stock h72 head with dual valve springs?

also if the h10 head is better then how much can it be reliability ported?

That's a fairly radical workover of a lowly round-port head. I wonder if the valves are too big for the little A12 bore. Certainly polishing hurts power though it was popular in he 1970s.

Reportedly it will outflow a stock A14 head.

thanks dd, I will try for the h10 head then since it will out flow an h72 and eventually I'll be getting 76mm forged pistons.

Dose anyone know how much you can port one of these heads before you hit a water or oil pocket?

plus I thought on an NA engine you can never go to big on valve size as the engine is going to pull the air in and push the air out. instead of forced induction when air is cramed in the chambers