Michael:
The oil pressure sounds low for 20W-50, but on the money for
10W-30.
The hot rodders rule of thumb is 10PSI/1000RPM. That is OK as a
guideline,
but what makes the engine work is flow, not pressure. You can have
great oil pressure, but if an oil gallery is plugged there will be no
flow and
something is going to break.
The load on the engine is not as important as the RPMs for oil
pressure.
Cold, my car (with 10W-30) runs 60-70PSI at about 3,000 RPM. Hot, it is
more like
50PSI at 3,000RPM, which is plenty. If you have medium or high mileage
on your
bottom end expect pressure to be a bit lower.
When idling, my car drops to maybe 20-25PSI, which is very close
to your
hot idle number.
What I get a kick out of is when I start the motor. The oil
pressure
hits full pressure one heartbeat after I start the motor. Great stuff.
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of SamuelsMA@aol.com
Sent: September 01, 2006 10:31 AM
To: 6pack@autox.team.net
Subject: oil pressure
Listers:
My '76 has had extensive motor work with the P.O., including porting,
high
compression (9.5 to 1), cam, lightened flywheel, and headers. It runs
beautifully, now that the carbs are rebuilt and tuned. I run 20W50
conventional oil
in it.
My question is that my oil pressure gauge shows only about 35 psi hot
under
load, and maybe 25 psi hot at idle. That seems low to me, but I don't
have
any basis for comparison. Also, I'm not completely positive what oil is
in
the car, as the mechanic who changed the oil last time may have put in
10W30.
What is the usual oil pressure hot under load and at idle for these
cars?
Could my gauge be reading low?
Thanks as always. Have a great holiday weekend.
Michael
'76 Tahiti Blue
CF 57044U
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