New Magnum heads for 347 with Flow data
Getting the exhaust out of the way I wanted to go back and try and unlock a little more flow above .450" valve lift. The port wants to stall at anything above .400" and I know it is because the S.S. can't handle the airspeed coming off the small pinch. At this point I have to make a choice between more time invested or leave well enough alone. Well I made the choice to go after some more flow because this engine is destined for my '73 Cuda AND because I know that a port that stalls on the flowbench is not going to yield a smooth power curve.
So using a 13mm wrench that measures .820" as a quick and easy Go/No Go guage I knocked almost .090" out of the pushrod pinch. Flow was up a noticeable amount but the stalling condition was still present.
.1 62.7
.2 125
.3 187
.4 224.5
.45 217
.5 215
.6 216
The stall is present at anything above .400" lift.
It's also important to roll out the sharp edge from the backside of the pinch. I use an inverted cone cartridge roll. J.Rob