Oil Pressure reading at Speeds ??
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Road Captain
Joined: Jun 2008
Posts: 714
Likes: 53
Oil Pressure reading at Speeds ??
Just trying to compare oil pressure readings with other Rushmore Twin Cams (Stock and Modded)
I am still running Stock Pump and stock plate
Start up cold is around 31-32 PSI
Running at speed after warm around 27-28 PSI
idle after warm up is around 13-14 PSI
Sound about normal?
I am still running Stock Pump and stock plate
Start up cold is around 31-32 PSI
Running at speed after warm around 27-28 PSI
idle after warm up is around 13-14 PSI
Sound about normal?
Last edited by 94 ultra; Jun 29, 2019 at 12:05 PM.
Thread Starter
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Road Captain
Joined: Jun 2008
Posts: 714
Likes: 53
I think my bike is fine
or at least it has been so far
just wondering how it compares
and with those with Blue pumps and Red pumps and Orange pumps?
or at least it has been so far
just wondering how it compares
and with those with Blue pumps and Red pumps and Orange pumps?
Last edited by 94 ultra; Jun 29, 2019 at 03:25 PM. Reason: edited i forgot Fueling
Stellar HDF Member
Joined: May 2015
Posts: 2,100
Likes: 307
From: mid Michigan
Have a fueling pump w/baisley spring I'm at 3/4 gage +- a couple hot or cold at speed. When I had SE think it was some over half gage W/ stock spring.i like lots of oil. My Chevy rebuild will be getting a high volume oil pump.
Cruiser
Joined: Mar 2010
Posts: 162
Likes: 16
From: Moorhead MN
I had my 88" built to a 103" and had issues with sumping using the OEM pump with the heavier relief spring running around 40 to 45 psi along with adding a oil cooler. Decided to try the S&S TC3 pump and cam plate and currently the issue has disappeared. The S&S shows 32 psi cold and slightly less at cruising speeds, hot idle is 15 psi and oil temperatures have stayed under 225 in the last 1100 miles with no cooler and lower 80's for ambient temperatures.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,957
Likes: 8,048
From: poway
I had my 88" built to a 103" and had issues with sumping using the OEM pump with the heavier relief spring running around 40 to 45 psi along with adding a oil cooler. Decided to try the S&S TC3 pump and cam plate and currently the issue has disappeared. The S&S shows 32 psi cold and slightly less at cruising speeds, hot idle is 15 psi and oil temperatures have stayed under 225 in the last 1100 miles with no cooler and lower 80's for ambient temperatures.
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Cruiser
Joined: Mar 2010
Posts: 162
Likes: 16
From: Moorhead MN
Originally Posted by Max Headflow
The issue is that adding the heavier spring on the stock oil system caused the motor to sump. If you'd left the oil pressure relief valve alone your motor would have run cooler. The SNS is a good pump. It has a higher scavenge to feed ratio. Dump more oil into the motor through a heavier spring and you'll have more oil to remove.
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Seasoned HDF Member
Joined: Dec 2005
Posts: 19,957
Likes: 8,048
From: poway
I learned a lot over the last few months. Everything that could have happened during this upgrade happened! I ran 40k with the Baisley spring with no cooler or issues. I was getting spiked oil temperatures inconsistently after the build and figured having the higher pressure along with the cooler it was causing cavitation on the scavenger side. So far the only issue of running at a lower pressure is between my ears.
TC pumps don't cavitate. It's a misused term here. The oil pump fails to scavenge for different reasons and the flywheels aerate the oil. Aerated oil (foamy) is harder to scavenge as it's volume is larger. Once sumping occurs oil temps will spike due to flywheels dragging in the oil. That drag (loss of HP) heats the oil directly which is why the temps spike.
In your case, since the motor seemed to sump after the build, I'd be more inclined to think that the reason for sumping was increased windage due to increased displacement or possibly greater cylinder leakage but there are many other factors that can cause sumping. SnS pump will definitely help tho.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,655
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From: Honah Lee
Sounds perfect to me. You will get plenty of oil to top. The relief is set 35 on most. You say TC but I thought it was and EVO. If it's a TC, then idle is below pressure release like it should be at idle.
Harleys just need 35 or less since that gives plenty of volume thru the engine. Cars need enough since they have to push it a lot further thru all those shell bearings and still make it to the last one. As the wear, oil pressure drop. Harleys do not have that problem.
Harleys just need 35 or less since that gives plenty of volume thru the engine. Cars need enough since they have to push it a lot further thru all those shell bearings and still make it to the last one. As the wear, oil pressure drop. Harleys do not have that problem.