<VV> oi pressure revisited

[Mark Durham]

That will only work if the spring is weak in the first place, but is an
easy test to see if that is the problem. What is missing in that
thought process is the realization that the spring holds 35 PSI when
the oil is cold now. This tells me there are other issues, like a worn
pump or mis adjusted cover plate or the clearances in the bearings are
loose, but he said he built a tight engine, so I,m guessing pump. Your
comment about the pump turning faster goes right along with that
thought process, too. If the relief holds 35 PSI when cold it should do
the same when hot, all other things being equal, but they are not, the
engine clearances expand a lot. This is why I suggested a 20 W 50 oil
as a test. The relief oil pressure should be somewhat higher when cold,
and stay higher when warm, too. He tried some STP which did affect the
pressure in the positive, like what a thicker oil would have done. Mark
Durham

Sent from my Windows Phone From: Daniel Monasterio
Sent: Tuesday, September 20, 2011 6:02 PM
To: hyarnell1 at earthlink.net; Mike Kovacs; VirtualVairs
Subject: Re: <VV> oi pressure revisited

If hot idle (600-700 rpm) is 20 psi and hot cruise (2500-3000 rpm) at
22-25 psi, I vote for increasing regulated presure by adding shims or
changing the spring as there is no significant change on oil pressure
when the oil pump gears increase speed by 4 times.

Daniel Monasterio

> From: hyarnell1 at earthlink.net
> To: kovacsmj at sbcglobal.net; virtualvairs at corvair.org
> Date: Tue, 20 Sep 2011 17:51:26 -0400
> Subject: Re: <VV> oi pressure revisited
>
> Stretching the spring will do nothing for the lower pressure you're seeing
> when hot. The relief will be out of the circuit at that point.
> Actually your pressures arn't out of line.
>
>
>
> -----Original Message-----
> From: virtualvairs-bounces at corvair.org
> [mailto:virtualvairs-bounces at corvair.org] On Behalf Of Michael Kovacs
> Sent: Tuesday, September 20, 2011 4:34 PM
> To: VV
> Subject: <VV> oi pressure revisited
>
> Just to see the result, I added a can of old STP I had on the shelf. The
> idle
> pressure now at hot cruise sits at about 22-25 PSI, Cruise still starts out
> cold
> at 35 (factory recommendation). Hot idle is about 20 PSI. All as I expected
> with
> the STP in there. Next is to put mechanical gage on and compare with
> electrical.
> Got new standard pump and will eventually get around to pulling parts off
> engine
> to replace the old pump.
>
>
>  What effect is there by stretching the spring?  Just curious. I think
> higher
> pressure as the spring acts like a pressure relief valve.
>
>  MIKE KOVACS
> ............................................................................
> ............................................................................
> ........................
>
>
>  1966 140 pg very well rebuilt engine by me. Balanced, bored, Steadman
> heads,
> mild cam etc.  Clark .010-.010 crank run out almost .000 and  plasti guaged
> carefully. 10,000 miles, runs very smoothly with strong  acceleration. 20-23
>
> MPG.
>
>   Starts cold at 850 RPM at 35 PSI oil  pressure. After a 20 mile drive with
>
> engine now at operating temp, Tach  at about 2900 RPM = 60-65 mph, the oil
> pressure now has dropped to about  20 PSI.
>
>
>  It will stay there unless the engine is idled back to 750 RPM = 13-15 PSI
> and
> is still running smooth and no lifter clatter.
>
>  Using fresh NAPA 10-40 oil. Clark filter. I forget if I did the oil pump,
> but
> probably looked it over and reinstalled.
>
>
>  I  assume the pressure relief valve is the reason for the 35 PSI cold. The
> oil
> press  gage is electrical and I assume it is accurate due to the steady 35
> PSI
> when cold even at cruising speeds. As oil heats, up just a steady  decline
> in
> pressure.
>
>  Suggestions? Should I check oil pump for clearence? Change filters? Check
> with
> mechanical gage too?
>
> By the way I use the same NAPA oil in all four operating Corvairs and they
> hold
> about 35 PSi when hot.
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