bjuice

ok here is a question that has stumped me..

i have the 632ci in my vette..it is a dry sump..( 4 stage WEAVER BROTHERS)...This isn't the pump with the built in vaccum pum.

ok i have a Moroso 4 Vane vaccum pump..this is the one THEY SAY is the best fit for dry sump motors..

ok guys here is the question i am running into problems getting a clear answer..

How much vaccum does this dry sump block need to be pulling ?

at the current moment i do not have a releif valve installed...I DO HAVE one..but i keep getting different answers to install or not install..since its a dry sump..

ANY FEED BACK ON THIS WOULD BE APPRECIATED.


Thanks

Brian

racecrafter

Hey bjuice, kinda new here and always enjoy reading your posts...along with many others.....cool site.....
anyway
I will start with the short answer, If your motor is happy, and the vaccum pump isn't injesting a bunch of oil I wouldn't worry about it. As far as a specific number well first I would need to ask where are you pulling the vaccum from ie valve cover, intake valley, block? and are you using nitrous or anything else that would have you running a ring package that would require high vaccum numbers.
One other thought...If you don't have some kind of data recorder or a gage with a telltale do you know how much real world vaccum you are pulling?

racecrafter

left something out ...If you are pulling more than 20" of vaccum you could be looking at some lubrication problems!

bjuice

hey thanks for reply...pulling from valve cover..no data recorder..

i think the smart thing to do is intall a vaccum gauage ..i agree with you 20'' would be extreme...

i need to do some checking and see what these 4 vanes pull...


thanks for reply.

ashtrak

Hey Brian, I know you have your vaccum pump already but you could maybe talk to these guys here. They may be able to help ya.Good luck
www.starvacuumpumps.com

gyrogearloose

Been running a dry sump for 6 years. (Burning alcohol) You would be smart to install a vacuum gauge and a check valve to control how much vacuum you are pulling. If you get up to and above the 20" of vacuum, this is where the wrist pins starve for oil and will go away on you. Not Good.
We regulate ours to 4" at full throttle down track and have found that as long as there is vacuum, your performance will stay the same reguardless of how much.
It will let you know how tight your engine is too.


gyrogearloose

bjuice

i dug out my relief valve and read the directions..the current shims in the valve is 4 shims open at 18"...3 shims at 16"....and so on..

i think i am going to install this valve and set it to open at 16"...this way i know i am safe until i get a gauge installed...

i feel i cannot go wrong here with the 20" ceiling here....if anything it would not be enough vaccum which doesn't hurt anything as far as oiling is concerned..

thanks again