moroso vacume pump questions

[wedge542]

whats best drive pulley size to go wth the 5 inch pump pulley,whats max vacume motor will take before problems,is it better to mount tank before or after pump,motor is sealed,will turn around 7200,thanks.

[Jamze Duncan]

whats best drive pulley size to go wth the 5 inch pump pulley? Don't know for sure. I'm using a 2.5" pully on bottom & 5" on pump, but appears the general tendency is to go larger on the crank pulley to produce still more vacuum these days. Have seen some Pro Mods recently using about a 4" pulley on the crank.

whats max vacume motor will take before problems,

have seen some recently pulling 20 lbs vacuum.

is it better to mount tank before or after pump,

AFTER, because the thing will quite likely pull some oil from the engine & you must be able to catch that before it blows all over the engine compartment or hits the track.

[wedge542]

thanks jamz,i saw a article somewhere that placing a catchcan in front of pump stops any moister before entering pump but you are right about mess everywhere,i guess that combo would need two catchcans,do you use a v-groove belt,moroso has the pulleys like a elec waterpump drive belt so it dont take as much belt tension not to slip but that kit is over a hundred bucks for two pulleys.

[Jamze Duncan]

[QUOTE]Originally posted by wedge542:
i saw a article somewhere that placing a catchcan in front of pump stops any moister before entering pump>
Believe the pump is hard anodized inside and the rotary vanes are composite, so i can't see where moisture could ever be mush of an issue. Mine eventually accumulates enough oil that it becomes less efficient - so have to pull it apart and clean the oil up ocasionally. I use a "V" belt - have never had a problem with belt slippage to my knowledge.

[wedge542]

thanks again jamze,how often do you need to clean the pump,so many passes,have you ever cked idle vacume and high rpm vacume?

[Jamze Duncan]

Wedge, my pump simply quits pulling vacuum when it gets oil in it (usually after lipping/burning pistons & such.) Maybe a tank before and after is a good idea - this should rather dramatically cut down on the amount of oil going into the pump. Mine pulls about 8lbs. vacuum at idle - don't know on top end. On a nitrous pro mod engine, what you see in the shop often don't correlate anyway, because when the thing gets hit with 3 healthy stages of nitrous, ring seal decreases and blow-by increases dramatically - this of course, means that little pump is trying to handle everything that blows past the rings into the crankcase - and still pull vacuum. At that point, I suspect it would pull little if any on a gauge, but you at least are not fighting a pressurized or "positive pressure" crankcase and that's the whole point.