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Old 09-27-2019, 09:38 AM
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Default Crankcase vacuum?

After a run down the strip I noticed that I have oil spray that came from my breather on the EVAC pump catch can.
I was told that if I add an adjustable regulator valve to my Moroso 4 Vane pump I can adjust to alleviate the issue.


My question is what is a normal range a vacuum gauge in my valve cover should read at idle and full throttle?

Is it safe to assume that full throttle is when the pump is picking up additional oil, I never had an issue at idle or mild driving.

Bob

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Old 09-27-2019, 10:43 AM
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In mine at idle is about 3 , at full throttle is hard to check to bizzy eyes on the road but I've read around 12 and mine is up in that range and the relief valve is adjusted all most all the way out. After about 100 miles I need to drain the catch can other wise it will spray oil.

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Old 09-27-2019, 11:59 AM
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i dont know if it will help, but i run a wrist band or cut sock over the breather just to catch any mist that may be developing. i think i have changed it once in years or so

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Old 09-27-2019, 12:00 PM
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If you get much more over 12 to 14 it could potentially cause the wrist pins to not receive enough oil.

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Old 09-27-2019, 01:06 PM
lakefect lakefect is offline
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wrap a shop rag around it , run as much vacuum that your seals and gaskets will take. its a myth about the wrist pin thing. i pull 12 at a high idle and 18in going down track. we tried 20 plus and suck the rear main seal in

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Old 09-27-2019, 01:10 PM
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Quote:
Originally Posted by mysticmissle View Post
i dont know if it will help, but i run a wrist band or cut sock over the breather just to catch any mist that may be developing. i think i have changed it once in years or so
That was my quick fix. :-)
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1966 GTO Post Coupe, 467ci. N/A Pump gas, best 1/4 11.6 118mph
1966 GTO Post Coupe, "The Bright Idea" 535ci. N/A Pump gas, best 1/4 9.58 141mph
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Old 09-27-2019, 03:31 PM
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perfect!

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1971 lemans sport convertible
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Old 09-27-2019, 03:47 PM
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Quote:
Originally Posted by lakefect View Post
wrap a shop rag around it , run as much vacuum that your seals and gaskets will take. its a myth about the wrist pin thing. i pull 12 at a high idle and 18in going down track. we tried 20 plus and suck the rear main seal in
X2.

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Old 09-28-2019, 08:35 AM
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how much power difference are you seeing form 12 to 18 psi? what rings are you running?

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1969 carousel red firebird 455, richmond 5 speed
1964 540 gto
1971 lemans sport convertible
1972 Maverick under slow construction
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Old 09-28-2019, 11:33 PM
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I only run 10 vacuum. I afraid of getting oil of the pins

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Old 09-29-2019, 07:18 AM
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I don't have any direct knowledge of the pin oiling concern but I'm skeptical that it's a problem.

What I do know for sure is that any crankcase vacuum is also working against the wet sump oil pump pickup. If the total vacuum on the inlet oil ( crankcase vacuum plus the sucking of the oil pump) gets low enough, the oil will cavitate. I don't know what the magic number is, but more vacuum is more risk. We regulated to 6 inches in the Grocery Getter and never had bearing or wrist pin problems. That amount of vacuum was enough to eliminate oil leaks and that was our main concern.

Eric

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Old 09-29-2019, 11:14 AM
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i started out with regulator on the valve cover and needed a sock on the breather. Switched to Moroso regulator on the pump and no longer need the sock. Have the smaller 3 vane pump, 4-5 at idle, 12-13 at the stripe. That worked for me.

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