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 Best Oil Pressure??

 Created by: croc7
Orig. Posting Date User Name Edit Date
Apr 12, 2017 03:22AM CooperTune  
Apr 12, 2017 01:53AM GeorgiaCracker  
Apr 11, 2017 10:23PM Alex  
Apr 11, 2017 01:36PM croc7 Edited: Apr 12, 2017 10:50AM 
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 Posted: Apr 12, 2017 03:22AM
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US
I picked up one of the adjustable Oil pressure relief valve caps. I installed it with a ball bearing. The engine it's in is a 67 Cooper S block and is daily driven. I'm not a fan of the ball, mine tends to bounce at idle 5 psi up and down. I shoot for 60 psi but it can move around. My engine runs a little warm around 210/220. Extended high speed runs tend to drop pressure a couple of psi. 

Your question and SB Chevy, I walked away from the auto machine shop biz in 2000. We were still working with cast iron then. There were several oil pumps for them. Std., Hi Vol, hi press, and hi vol/press combo. If you think about it oil pressure is a result of bleed. Each bearing receives pressurized oil and it leaks past the side clearance and bearing to journal clearance. Small block has 8 rods, 5 mains, 5 cam bearings. They also use the oil to pump up their lifters that's 16 lifters to leak oil as well as 16 push rods carrying oil and spraying the rockers. 

Oil pressure can be adjusted by working with main and rod housing bores, rod and main bearing journal dia. and rod side clearance. As we know oil does not only lube but also cools. With the correct choice of pump and clearances pressure can be almost any thing you like. The pressure number is not as important as having some pressure. Steve (CTR)

 Posted: Apr 12, 2017 01:53AM
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US
Both of my most recent 1275's ran 50psi at idle and 70psi at anything over 1500rpm, and this after being warmed up. Who knows how accurate the gauge is, but if memory serves way back when I had Midget and Sprites it was similar, except for the very first 948 which was much lower and needed a rebuild. When warm it would idle at 10-15psi, and maybe hold 35psi running down the road. But it still ran ok.

 Posted: Apr 11, 2017 10:23PM
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GB
70 seems a bit high to me - my race engine which has the pressure set by the manufacturer (CMES) only runs at 60-65psi.

 Posted: Apr 11, 2017 01:36PM
 Edited:  Apr 12, 2017 10:50AM
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I've heard from as low as 60 PSI to as much as 80 PSI or a minimum of 10 PSI per thousand engine RPM.  I've been fiddling with different spring lengths, washer stack-up and bouncing between using the plunger/bullet or ball.  Settled in at a spring length of 2.8" and the ball for 70 PSI at cruise.  Care to offer insight on why the mini engine has such high oil pressure compared to a small block Chev engine?