#1  
Old 10-30-2023, 10:49 AM
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Default OIL PRESSURE ?

Upon startup, my auto meter gauge says 48#. Line connected by the dizzy.
Connecting a Mac tools gauge it says 52#.
Moving the Mac gauge to the oil filter housing it reads 62#.
Motor has a 60# pump.
Normal ?

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Old 10-30-2023, 11:30 AM
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That's because at that point in the oil system your reading all the restrictions in the oil system up to that point ( all the 90 degree turns to get there ) and if you have the bypass blocked in the oil filter adapter then your reading the restriction of the oil filter also.

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Old 10-31-2023, 04:25 PM
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There is bound to be a small difference between gauges, I wouldn't worry about that. Steve is right about picking up the pressure from the top by the dist. or at the filter adaptor. There will be a slight difference. I have my pump shimmed for the bypass to open at 75lbs. But on start up when cold the gauge reads around 90.

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Old 11-01-2023, 06:24 AM
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Sounds normal. What oil filter are you running, and what weight oil? I'm running two oil gauges. One at the oil pump and one off the distributor. They read pretty much the same. But I'm running a Wix high flow racing oil filter. 20w-50 Amsoil oil.

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Old 11-01-2023, 07:40 AM
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What engine RPM at start-up on a cold engine?

RPM plays a HUGE roll in observed oil pressure.

Temperature also effects what you'll see on a cold start.

Oil type and viscosity are also players here.

My engines also shoot the gauge well past 60psi on a cold start even with a 60psi oil pump spring. I've seen 80lbs plus on really cold days past 1500rpm's or so.

The pressure eventually comes down to about 20-30psi at idle speed (engine warmed up) and anything past 1500rpms it's pegged at 60psi. All five of the engines I had in the Ventura over the last 40 years were almots exactly the same far as observed oil pressure (take at the distributor).......FWIW...

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Old 11-01-2023, 05:28 PM
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Wouldn't 90-100 psi reek havoc on distributor composite gears?

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Old 11-02-2023, 12:02 PM
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1500 RPM on cold startup. 60 degrees.

Valvoline 10W30

Seems a bit low to me ?

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Old 11-07-2023, 06:11 PM
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Not that much distance between the oil filter adapter fitting for the gauge and the hole by the distributor. A straight 1/2" diameter shot straight in to the engine for about 10" and then a turn up to the hole that might add another 6", and after that the passage continues to the front of the engine and there's all sorts of drainage points. Both spots should be really close in pressure readings since all the loss occurs after that. I could see a notable difference if we were taking a reading at the tail end of the passenger gallery.

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Old 11-07-2023, 07:46 PM
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Need to correct my last post. If using the slanted oil filter adapter used on A-bodies then the pressure reading on the adapter would be before the filter and that would account for some of the pressure variation.

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