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HP500 (Carb) oil pressure

Old 05-18-2021, 08:06 PM
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Default HP500 (Carb) oil pressure

Ok oil gods!

Bought a used HP500 from a reputable place, compression and leak down were all within spec. 270 hours on the motor, 70 hours on a fresh top end. Currently running 20w50 dino oil and a wix Racing filter. Oil pressure is 58-62 psi idle start up cold, 49-55 psi Turning 5k rpmís (hot.) 40-45 psi turning 3500 rpms. After a moderate or hard run the pressure at idle will drop to 12-14 psi(in gear 750-800 rpm). After a couple of minutes will rebound to 18-20 psi. Bump the throttle to 1000-1200 rpm and then pressure will be 25 psi or so. All confirmed on a mechanical gauge. Is this normal or should I be concerned. Didnít see any metal in the last filter. But it only had a handful of hours on it.
Thoughts and guidance appreciated!
I should note I do not have a oil temp gauge... I know I know itís the next purchase....
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Old 05-18-2021, 11:16 PM
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Perfectly normal for a performance engine to be that way. Not unusual at all.
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Old 05-19-2021, 12:09 AM
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That is pretty normal.
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Old 05-19-2021, 10:34 AM
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Perfectly normal. Your heart sinks the first time or two it happens but itís common after even a mild flogging.

Fwiw, I oversized my oil cooler using a thermostat and it minimized that dramatic swing a good deal.
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Old 05-22-2021, 10:37 PM
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I saw the same with my 502s with factory oil cooling and just about had a heart attack when they dropped to 20 lbs. Doing just as you described showed the same results, and when I did a tear-down on both this past fall, the bearings were in great shape. The rebuilds have huge coolers and Iím using high volume pumps so this should be minimized.

On my buddyís Cig Bullet, 454s and blowers, the oil pressure hardly drops at all even after beating the snot out of it so I was really surprised when my stock 502s lost so much pressure. His set-up... no thermostats and huge oil coolers.
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Atpsr22 (05-23-2021)
Old 05-22-2021, 11:08 PM
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those numbers all match our 500efi...+\- a few psi
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Old 05-23-2021, 10:18 AM
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Thank you all for the input!
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Old 05-23-2021, 02:31 PM
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Might try 25/50
but harder to find than years ago, in my area at least!
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