Second reason to not use valley for relief woudl be why woudl you want to pull outside air through your engine. Best place for one if you must is on the pump itself.

X2!

Yep ! I've seen a lot of motors with the relief on a valve cover, and then they wonder why they keep filling the catch tank

My suction hose fitting is mounted on the right front valve cover next to the bypass valve and it gets moisture only in the tank after a day of racing using a enhance GZ pump that pulls only 5.0 inches of vacuum

I was told you wanted to get a little amount of oil back to the tank that way the vac pump is getting lubed ??

Who told you that?
I'm thinking there are a lot of tiny oil droplets in the motor being slung around, especially after 4500 RPM
I had a 12.0 inch long baffle welded into my right side valve cover with a lot of 3/8 holes drill in it to act as a trap to help not let a lot of oil be slung into the fitting going to the pump. It vibrated loose the welds and I removed it this year, it has less oil in the tank now after 5 or 6 runs than it had before with the plate: confused:

Fred Flintstone loved his.........

I ran one of those systems for a short while on my old A/SA M.W. NHRA stocker a long time ago, it would suck in a lot of moisture after every run and condensate in the valve covers making a milky mess with the oil, NOT GOOD: down :

My contribution to this thread......

I dyno tested a 557 BBM with -1 heads on it that the owner was trying a vac pump on.
He had the fitting in the valley cover.
We had made several pulls with valve covers that had breathers and no belt on the pump.
Swapped covers and hooked up the belt.
I barely got to WOT and the puke tank was over flowing.

Took the hose off the puke tank and had it aimed into a bucket.
At WOT it looked like a fire hose amount of oil coming out.

Valley cover = Not a good place for the fitting.

Good for you helping on this post

How about a 4 vane Moroso pump? My machinist told me to not even worry about regulating it with an aluminum block. Your thoughts Al?

I use a Moroso 4 vane and I am happy with it.

I do regulate it.

How much vacuum to run is a whole other discussion. I limit mine to 12".

However I know that the more vacuum I let it pull the more horsepower it makes.

I think Star is considered the top of the line.

I personally do not regulate them. Never have cant make enough vacuum to hurt it. But your results may vary. We have pulled 20"ish with a 4 vane enchanced in BBM aluminum block stuff with one. That number scares alot of guys who read magazines and internet forums though. I have NEVER hurt a wrist pin in any of my deals to date. Nor have we in the red car which is the same set up and results.

IMO a 3 vane is PERFECT for those folks, why I suggest it for most. Throw the regulator away or dont buy one and save some money for something else. We have pulled 12+- with a three vane in the dragster back when we used one. Also have one on the street car doing the same.

Same deal here….. morose 4 vane w/t Star regulator. ……but I don’t have a top shelf aluminum block so I’ll get back on the porch.

(Disclaimer: jeff and I will make any snide comment available at each other’s program, but it’s all in jest and we usually learn something in the process….. carry on )

I think the Star pump is very nice quality but on a quieter street car annoying from the vanes -clack -clack -clack -clack.....

Second to that, the regulation of pressure was at the pump itself but they recommended using a separator between pump and engine. Soooo, as the foam media gathered oil the amount of vacuum between pump and separator remained at whatever you set it at, but between separator and engine would quickly go from negative to positive as the media became more restrictive. I felt with that design the regulator should have been on the hose between the separator and engine (as to maintain negative pressure on the crankcase consistently) but Star did not agree. (so I moved on)

Now using a GZ pump as it has more of an oem appearance and is quiet.

I have a Moroso vacuum pump fitting like pictured in my valve cover oil fill cap with no issues and a Moroso enhanced 4 vane pump.

IMO wherever it ends up I woudl use the Star baffle where it attaches...

In the most forward area of the valve cover!

I have a Moroso 22641 pump (4 vane). Pickup on top the valve cover b/t rocker arms. Just a straight fitting w/ no baffle. I use a regulator mounted on the pump, but it's as tight as it'll go...might as well remove it. Pulls 10-12" or so and no issues filling the tank w/ oil at all.