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[Healeys] Pressure relief valve

Subject: [Healeys] Pressure relief valve
From: rrengineer.mike at att.net (Michael MacLean)
Date: Sat, 30 Apr 2011 20:19:40 -0700 (PDT)
First of all, get a calibrated in-line oil pressure gauge and find out what
your actual oil pressure is BEFORE you adjust anything.  You would be
surprised to find out how "off" the dash gauges can be.  Then you can play
with the relief valve.  By the way, 70 PSI is not too high for lubrication,
but you may be bypassing your filter.
Mike MacLean
56 BN2
60 AN5

--- On Sun, 5/1/11, Bob Spidell <bspidell at comcast.net> wrote:

From: Bob Spidell <bspidell at comcast.net>
Subject: [Healeys] Pressure relief valve
To: "healeylist" <healeys at autox.team.net>
Date: Sunday, May 1, 2011, 2:16 AM

Background: my BJ8 has run low oil pressure at idle for as long as I've had
it. At startup I get 60psi, but after running on hot days I would register,
for all intents and purposes, zero psi at idle. In spite of this, the engine
has run and performed well for me for over 100K miles. I use 20W-50 dino oil.

There has been a lot of discussion on the BCF about replacement relief valve
springs being shorter than spec.  It has been suggested that putting washers
or other shims or a 1/4-inch bolt behind the spring could increase running
pressure.  I actually didn't believe it because AFAIK the valve is there to
keep pressure from getting too high, and presumably would be fully closed at
normal running pressure.  But, I was curious ...

So today I pulled the relief valve and measured the spring at 2 & 11/32";
quite a bit less than 'spec.' So I installed the 1/4-inch bolt and fired her
up; 70psi on cold start/fast idle--not too surprising. What's surprising is
even after the engine has warmed-up--when I would normally see 10-20psi,
before a long run in hot weather--I am getting 40psi. And the max pressure is
still at 70psi; so the effect is max pressure is up 10psi, but the hot idle
pressure could be up 10-20psi!

My questions to the forum are: is 70psi too high a max oil pressure? Any
explanations for this phenomenon? Should I split the difference with some
shims?  Go back to the spring-only setup so I can sleep?

Bob

-- *******************************************************************
Bob Spidell           San Jose, CA            bspidell at comcast.net

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