ProComp/Speedmaster aluminum heads
what is your opinion on the CNC Speedmaster head as a budget performance head.
Typical of what you see anymore. Big, blown out bowls and a runner too small to feed it. Oversized valves to fill up the huge bowl.
Last set I did was for a big block. It actually went almost 900 on the dyno which was over a hundred more than I guessed. I had the dyno sheets faxed to me and the numbers looked legit. And the time slips matched what the dyno said.
As far as casting go, they are fine. I've never seen a set of heads like that that don't need a valve job. With a bowl that big, they get a 50 degree seat.
The issue is always the same. You are still using mid 1969's architecture. Without offsetting the intake rocker (and maybe the exhaust...I think the last time I looked at my W2 junk I was thinking about an offset exhaust but why I thought that at the time I don't remember) and raising the port, you are stuck. The small CSA makes air speed go through the roof, so you do things you don't normally do to control it. Everybody and their mother thinks the faster the airspeed the better, but that is just not the case. You need to CONTROL the air going through the port (or, picture the head moving through the air...) and sometimes, more often than not, air speed is your enemy. The flow bench will tell you the port loves airspeed. Sometimes you have to ignore the flow bench. Especially on the exhaust.