vacume pump pulley question

Has anyone used standard size aluminum crank pulley apposed to a mandrill, and a small pulley on the vacume pump ?

No, but if you use a big crank pulley, you'd need an even bigger pump pulley to keep from spinning the snot out of it. I don't know how fast is too fast, but if you use a 4" or bigger crank pulley, the pump pulley would need to be pretty daggum big to slow it down...and I've never seen a pump pulley bigger than 5".
The typical setup is a 3" crank pulley w/ a 5" pump pulley IIRC.

an8sec70cuda is correct you don't want to overdrive the pump. here's what Moroso says max rpm is for their various pumps.
"Moroso Vacuum Pump Nos. 22640 and 22641 can be driven no faster than 6500 RPM. The Moroso Vacuum Pump Nos. 22642 and 22643 can be driven as high as 8000 RPM. "

Joe

Thanks for verifying my thoughts

Rule of thumb is 50% smaller pulley on crank, larger pulley on vacuum pump

I do 36 vacuum pump pulley and 18 teeth crank pulley.
Or a 24 tooth vacuum pump and 12 tooth crank pulley.
I personally use a Gilmer teeth setup.

Pretty easy math. If you spin and engine 8000rpm and ruin a 3 vane moroso it will need to be underdriven 20%. If you run say an enhanced 4 vane it can be driven 1 to 1 at 8K. Spinning the pump as close to max rpm as possible will yield the highest vacuum possible as its linear, it wont make 20+ at idle that generally requires a fair amount of RPM not to mention a very well sealed engine.

Al so the vacuum pump pulley would have to be 20% larger than the crank pulley ?