Vacuum Pump Bypass Setting?

Old 05-05-2013, 05:54 AM
  #1  
TheEngineer
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Default Vacuum Pump Bypass Setting?

I have a stroker SBC 427 race engine with 14.7-1 Compression, wet sump and it turns 7500 RPM. I just installed a Moroso enhanced 3-Vane vacuum pump with a Moroso 22637 relief valve. Internal shims in the relief valve change the bypass settings.

The valve has five different inch pound bypass settings; 10, 12, 14, 16 and 18. I just set it in the middle to 14 inch pounds (not knowing exactly where it should be). It is pulling about 5 inch pounds at an idle and increases with RPM.

So, what does everyone think the bypass should be set to on this engine?
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Old 05-05-2013, 08:22 AM
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markdunlap
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Default Vacuum

My choice would be 12" max.

Too much vacuum and lubrication can be robbed from splash parts like wrist pins.

Otherwise, what ever makes highest dyno figures or fastest ET.
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Old 05-07-2013, 07:03 AM
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hammertime
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12-14" will be plenty at rpm.
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Old 05-07-2013, 08:02 AM
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TheEngineer
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Thanks for the inputs!

I have a race this weekend, so I'll get to see if the car picks-up some with the new vacuum pump. The car has been running fast and very consistent this season, with 1.28 60fts and 5.80s 1/8 mile ETs @ 118 MPH. Foot-braking it in the NO-E class.
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