Wayyyy.
915 J 1971 casting [email protected], [email protected], [email protected][email protected], [email protected]=3 angle valve job & 186 cc ,hard seats on int proud in the chamber. Most of the work in the roof ,widening the port , and leveling the floor before the turn...guide skinnied n left long.
I pass on all those experimental / oddball seat angles. Longevity is more important to me and ultimately I get where I wanna go, just fine , without it. It's there if you search hard enough... I have spent a weeks time, conservatively here and there, on one port, in order to find it. Back cuts, sets angles...worth 4-9 cfm, sometimes... other times they speed the air and create a revisit somewhere else to correct the fall off. Gordon said it earlier in this thread, something like or about how to just get "close enough" to the goal, in some heads, is good enough...because that next move can sometimes bring headaches.
You'll definitely find more in that head. You may.. or may not, trade 4 cfm 'down low' to see those 290's... I doubt it... but i know you have a good 12-15 cfm waiting on the next page for ya.
