SBM Edelbrock/Speedmaster Head Data

Newbomb Turk said
No, I’m saying that looking at your flow curves the 50 took a bigger dip than the 45.

I forget the valve size exactly but at a 2.055 valve the .25 l/d ratio is .5138 lift and a 2.08 valve is .520 so you should be well past where the valve has a bunch of influence on the flow curves.

I’m a bit bewildered by that curve. Usually at high lifts the 50 and steeper seats don’t do that if the port has the cross section to support it.

Have you put the valve in the guide from the spring side and flowed both ports??

That may get you going the right direction.

Sorry for the confusion, but the two tests shown this time are both 50 deg. They are the same port, just showing the progress over 1 week. 1/8 identifies that it's cylinder 1 or 8, then the date is shown.

So, the bigger dip is a result of lots of work on the short side and some in the chamber.

And it is definitely an area thing. Once the short side is lost, a majority of the air is going over the valve and toward bore center. Finding area in the 0.550"-0.650" lift range is the key. It's hard to do. Laying back the short side helps some, but eventually the mid lift flow will suffer. I'm going very slowly at this point because I have a pretty good port going. Don't want to mess it up.

Haven't flowed with the valve upside down lately, nor have I tried the different test pressures. Maybe I'll try that in the morning.