<VV> oi pressure revisited

[Michael Kovacs]

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
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 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.