Here are some results from recent testing I've been doing on a Speedmaster head with 2.02 intake valve. I've enjoyed digging into the data so I thought some of you guys may like it. The methodology is somewhat scattered because I'm looking for flow in certain areas of the curve. That approach led me to try changing valve angles and seat angles. Ignore the pink, green and blue scribbling on the data chart - that's for my own use.
The data sheet shows that 6 different flow tests were run with 4 different valves. Those valves were put into an optical measuring stand and the profile of the valve was plotted. The 4 valve profiles along with the chamber cross section in the shrouded area (as indicated at the green arrow) are shown on the drawings. At low lifts it's fairly easy to make a direct correlation between the drawing (look at the valve curtain area) and the flow numbers. The enlarged drawing shows the 4 valves at a lift of 0.100". The 0.016" measurement is just thrown in for reference. It shows the height difference between the Edelbrock valve and the Speedmaster 35/50 valve. In other words, the SM valve blocks off the port more than the Edelbrock valve at the same lift point.
The first 5 tests were run with a 45 degree seat angle. For the last test the seat was recut at 50 degrees and a different valve was used. There were no other changes. And yes, this made the 50 degree seat too wide.
I'm not really tying to make a point or draw any conclusions, other than to point out what a large difference a few thousands of an inch and/or a few degrees of angularity can make in flow. This is not a true test of valve angles or seat angles, just some random tests I was running for other reasons. I already had the info printed anyway so I thought I would share it.
The data sheet shows that 6 different flow tests were run with 4 different valves. Those valves were put into an optical measuring stand and the profile of the valve was plotted. The 4 valve profiles along with the chamber cross section in the shrouded area (as indicated at the green arrow) are shown on the drawings. At low lifts it's fairly easy to make a direct correlation between the drawing (look at the valve curtain area) and the flow numbers. The enlarged drawing shows the 4 valves at a lift of 0.100". The 0.016" measurement is just thrown in for reference. It shows the height difference between the Edelbrock valve and the Speedmaster 35/50 valve. In other words, the SM valve blocks off the port more than the Edelbrock valve at the same lift point.
The first 5 tests were run with a 45 degree seat angle. For the last test the seat was recut at 50 degrees and a different valve was used. There were no other changes. And yes, this made the 50 degree seat too wide.
I'm not really tying to make a point or draw any conclusions, other than to point out what a large difference a few thousands of an inch and/or a few degrees of angularity can make in flow. This is not a true test of valve angles or seat angles, just some random tests I was running for other reasons. I already had the info printed anyway so I thought I would share it.
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