i just purchased a 4 vane moroso and going to run on my 622 dry sump.
i also purchased the relief valve and was advised to go with 3 shims which will open at 16 inches of vaccum..
these motor builders on here know more about this vaccum than i..but i would like to ad if you have not purcahsed your pump yet i would recommend AUTO -FAB RACE CARS for the purchase of this pump and relief valve...My total savings was $150.00 over what you can purchase from JEGS OR SUMMIT.....
Rob Hamilton is the owner they are out of Baltimore MD...410-796-8777.
They Built Gil Mobleys 10.5 69 camaro...thery are a full line chassis shop and parts house...GREAT AND TIMELY SERVICE...
ask them about their other parts...CHEAP compared to Jegs and Summit.
thanks- BRIAN
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "