<VV> oil pressure question

[kevin nash]

> 
> ------------------------------
> 
> Message: 7
> Date: Thu, 15 Sep 2011 17:29:52 -0700 (PDT)
> From: Michael Kovacs <kovacsmj at sbcglobal.net>
> Subject: <VV> oil pressure question
> To: VV <virtualvairs at corvair.org>
> Message-ID: <1316132992.11640.YahooMailRC at web82006.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
> 
>  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. 
> 
> 
> 
> 
>  MIKE KOVACS
> 
 Mike- Yes, your oil pressure is a little low- I would check to make sure that the clearance between the gears and oil pump coverare good, (.002 to .004) and if the clearance is much more than .004, that is likely most of the problem. Also, check the clearancebetween the gears and housing- I dont remember the spec though! If the clearances are reasonable, it might be worthwhile to put a high volume oil pump in, (but then switch to 10-30 oil) as thats the only sure way to up the oil pressure at idle-stretching the oil pump by-pass spring doesnt do anything at idle and isnt as effective as putting a larger pump in. Kevin Nash