IF you run a vacuum pump, how much vacuum should you set it up for? What is the desired crankcase vacuum I should shoot for?
thanks

I have heard 14" of hg... I have mine set at 12"..
if you go too high it strips the oil off the wrist pins
so I've heard

I don't desire much because of all that talk about wrist pins. 5 or 10" would be enough for me. I have 13" and if I ever have a wrist pin problem I'm gonna feel real stupid.

Here's something to think about: The absolute air pressure in a sump, along with the oil height over the pump inlet, are the only things pushing oil into the oil pump. Decrease that enough and you're going to have oil problems. On the other hand it seems that the more vacuum in the crankcase the more power the engine makes.
So it's a balancing act.

R.

I know some high buck racers that use 17 inches, they did have to open the wrist pin to rod and pistons clearances some, close to .0010. This is a all out drag motor that leaves at 7200 RPM and shifts at 9600 RPM I haven't ran one yet but I'm buying parts with the intent to set the bypass valve at 15 inches to start with

I have been running 12-14.5 inches with no modifications for a few years with no problems.