J heads upgrade

Just one more thing I can't let pass.

If you chose your cam based on where the port starts to stall, how do you chose which pressure drop to test at? This has been a pet peeve since I bought my flow bench.

If you test a head at say 10 inches, where most bench top benches still test at, your port may look good to well over .600 lift. Bump it to 25 (the Super Flow standard) the lift at which turbulence occurs will be much closer to .500 lift. Drop to 28 inches and turbulence will occur sooner. I have tested as high as 48 inches on a production head (will be doing some W-2's before the end of the year and my push it to 60 if I can) and I will tell you the port on a production head is a turd as soon as you open the valve.

The point is, you can't pick you lift based solely on flow verses lift numbers. Sometimes,you have to lift it as much as the valve gear will let you. Other times, reliability, parts and output dictate lift.

At this point, I can't see any reason EVER, to not NET .500 lift on any application. That's why you need to develop a relationship with a cam grinder.

Hope this helps someone. I'm sure others will argue.

To the OP...a bigger valve, on the heads we are discussing, will increase low lift flow, to the detriment of mid and high lift. Low lift being, in this case, .075-.175 and mid being .175 to about .250 lift. You'd be better off with a 1.88 valve, a steeper angle valve job and a faster ramp on both the intake and exhaust lobe. That may be out of you and your machinists comfort zone. If so, use the 2.02 and use a slower lobe on the intake. The longer you keep it at low-mid lift the more power you will make.

We could discuss a 2.02 valve and a 50* seat, but that would tip some viewers over. And, some castings won't take it. Don't ask how I learned that.