[TR] TR2/3 - oil pressure adjustment

[Randall]

---- Angelo Graham <agraham at execulink.com> wrote: 

> My '2 had the early filter head with the partial full-flow feature.

Not "full flow" at all, it was a bypass type filter, designed to take wool felt filter cartridges that wouldn't flow enough oil to feed the engine.  So the engine was fed with oil direct from the pump, and the filtered oil was returned to the crankcase (to be sucked up the next time).  That sounds really bad, until you consider that many successful engines (eg the Model T and VW bug) had no oil filters at all!

> My engine seems to be 
> running a high oil pressure - around 50 lbs. at idle and going up to 
> around 70 - 80 lbs. revving or under load. I feel this is a bit high

That is perfectly normal, I would leave the adjustment alone!  Practical Hints calls for 70 psi minimum with hot oil and traveling at speed.  If you would like to see only 70 psi instead of 70 to 80; try using thinner oil.  Assuming you are still seeing 80 with the oil thoroughly warmed up; without a thermostat it takes much longer for the oil to get up to normal operating temperature than shown on the dash gauge.  A fresh engine shouldn't need 20W50 unless you routinely drive in desert conditions.  Again Practical Hints only recommends up to 40 weight.  (Note that the 20W portion of your oil's rating refers to its "winter" performance, below freezing.  At operating temperature, it's a 50 weight oil.)

> Do you try to get the adjustment at idle and that should set it for the 
> entire range?

NO!  The pressure relief valve should only start to open at 70 psi.  In the vast majority of cases, it will not be open at all at idle.  And even once it starts to open, it operates over a range, so the pressure will still not be entirely constant.

> I have a freshly rebuilt engine with no apparent problems and using 20 - 
> 50 oil.

Stop worrying, get in and drive!
Randall