Speedmaster Small block porting tips and results Part 1

MOPAROFFICIAL said
Wayyyy.
915 J 1971 casting
[email protected], [email protected], [email protected] [email protected], [email protected] its 186cc
3 angle valve job , 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 definitely can find more in that head, you may or may not trade 4 cfm down low to see those 290's... I doubt it... but you have a good12-15 cfm waiting on the next page for ya.

What's not reliable about a 50 degree seat?

The funny thing is I know there are many guys out there doing some variant of a 50 on everything from street cars to their race stuff.

I've used it on 2.3 heads, and last time I checked on that engine (mid December) that head is still the best they've come up with, and it's still the best on the dyno and at the track. And that's after Esselinger squealed like a stuck pig when the found out I was not only changing their valve job, but correcting their crap CNC porting.

I know, for 100% surety, that I'm not the only one who doesn't pick a valve job based on lift. I know personally (through PM messages and such) that there are guys who are using some variant of a 50 on lift rule stuff. All under .500 lift. And it works.

I've never been fond of doing R&D for free, but I've also never sat back and let technology go by without doing my own investigation. And making my own judgment.

It doesn't take long on a flow bench to understand why steeper than 45 degree seats are becoming the norm. Irregardless of how much David Vizard and a bunch of other guys harp on low lift flow and flatter than 45 degree seats for less than .600 lift stuff.