View single post by CDA951
 Posted: 07-13-2019 03:49 am
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Joined: 04-16-2018
Location: Santa Barbara, California USA
Posts: 20
During our epic 8,000-mile cross-country road trip in #19250 (as shown on the J-H Facebook page), we learned the nuances of our engine's oil system. I had rebuilt the engine and it had about 1,500 miles on it when we started, and bearing clearances were all within factory specs.

I come from the Porsche world, and air-cooled 911s run similar bearing clearances as the 907; the rule of thumb there is about 1 bar (14.7 PSI) of oil pressure per 1000 RPM when hot, up to 5 bar. I noticed that our 907 engine (running Total Classic 20W-50 oil) generally follows this trend, though when hot the max pressure does not go above 4 bar/60 PSI, which I would consider low for such a high-RPM engine as RedRacer states. I didn't replace any oil pump parts during the rebuild (pump rotor clearances and endplay were within spec, though I later learned from JAE that I should have replaced the rotor/annulus!).

We have the Champion radiator, JAE water pump with later impeller and an oil cooler installed. We drove the car in 100+ degree desert temps in Las Vegas on the way out and across the Mojave desert on the way back, and it was over 90 degrees and humid much of the trip, so more extreme than our customary mild weather here in Santa Barbara, CA!

I think I will try to shim the relief valve a bit to see if that helps. The downside of this "mod" is that it can cause cold pressures to be too high, which can blow out oil seals in extreme cases . . . .

Last edited on 07-13-2019 03:51 am by CDA951