How much vacuum is ideal for street use 572 wedge. I now have around 5in. Would a smaller pulley on the pump be the way to go. The pulley on the pump now is 4 1/2” diameter. How much smaller pulley would kick it up to say 10”. Thanx for your time.

Wet sump? Dry sump? What pump and pulley ratio currently?

I would smoke test it to see if you have any leaks to start.

I would have thort, if you had a good pump, you would have to set the relief to control your peak vacuum. I have 5" at idle & 10" at WOT with a Moroso 4 vane pump. As mentioned above, you might have a leak so maybe you need to test your system. I do know my pump is worth 0.12 to my ET. when it had a fail we looked at where the power went & found the pump drive was faulty. Once fixed the missing ET returned.

Easy to make a fitting and use a $5 Harbor Freight regulator. Ring seal and the engine being sealed up will vary the result. Air up the motor with 5psi and spray with soapy water. If you have a leak it'll show. Mine makes about 10-12" with 5 at idle. GZ pump.
Doug

I had less than 5.0 inches on my 505 C.I. race motor in my S/P Cuda with an enhanced GZ vacuum pump in neutral at 1000 RPM up to 5000 RPM
The next race motor will have a four vane Moroso, or dry sump oil system. I'm hoping for 12.0+ inches revved up above 5000 RPM

Same here.

I can regulate it for 15 but adjusted to 10.

I have a 4 vane Moroso on my 575" hemi that pulls about 10" at WOT.

Ok thanx guys. I just checked it at idle, had about 5. Didn’t check it with any rpm, that will be next. I’ll post some pics of my new ride someday. Here’s the engine.

Ran a vacuum pump for years on the street. Not sure why anyone would want to regulate the vacuum it makes, usually any extra just helps ring seal along with other things. bang for the buck, its hard to beat a maroso vacuum pump, but there is other good options as well.

When people say what vac they pulling , they should say what block material . Alum or cast iron will make a difference

Same here on my 528" Hemi.

I have not had a BB of mine pull less that 15" of vacuum at WOT in YEARS,if it does not its leaking somewhere. Generally all 4 vane enhanced or Star pumps(seem to be a tad better) These are all aluminum block deals and wet sumps. The Stratus pulled 19" with a dry sump and vac pump.the one iron block we did when my son first started racing the dragster as his "training wheels" was a 446" stock block that we pulled 11" at WOT. FWIW the heads up car has seen 19" as a wet sump with a moroso 4 vane on an aluminum block driven by a serpentine belt. But it is a brand X deal.

Again it'll pull more vac than 5 at higher engine rpm. You have to do the math with pulley ratios. Be aware that each type of pump has its RPM limit.

It’s a gz. I did raise the rpm roughly to 4000, pulled 10” so it’s working fine. Never had a vac pump, just getting so input. Thanx everyone.

I would have thort, if you had a good pump, you would have to set the relief to control your peak vacuum.
I have 5" at idle & 10" at WOT with a Moroso 4 vane pump. As mentioned above, you might have a leak so maybe you need to test your system.
I do know my pump is worth 0.12 to my ET. when it had a fail we looked at where the power went & found the pump drive was faulty. Once fixed the missing ET returned.

We have a new 4 vane enhanced Moroso with about 4 dyno pulls on it for sale.