Pressure relief valve in back of Block

[patrickt]

Originally Posted by ERA Chas

Because it was originally shimmed to 100PSI by the machinist. I changed that fast while on the dyno. Would still prefer 65PSI but this is within a good margin.

Maybe it's right on the money and your gauge is off a little bit. I wouldn't waste any worries on it though. But just in case anybody ever asks you can tell them that Ford's NASCAR engine blueprinting specs for 1967 called for the relief valve to start opening at 50 to 65 PSI.

[ERA Chas]

Originally Posted by patrickt

Maybe it's right on the money and your gauge is off a little bit. I wouldn't waste any worries on it though. But just in case anybody ever asks you can tell them that Ford's NASCAR engine blueprinting specs for 1967 called for the relief valve to start opening at 50 to 65 PSI.

I don't waste any worries on it because this is the 3rd OP gauge tried in the car and #'s 2 and 3 matched. #1 was very high. Also the idle PSI would not be a near perfect 22. The hot numbers on 5W-30 Mobil 1 (no longer used) were 17 (1000 RPM) and 65 @ 6800.

Forty-two years ago Ford NASCAR motors (which made 510 or 20HP in race trim) ran on straight 50 weight (and most with additives like STP syrup) so it was prudent to bleed pressure before the filter blew off. Now 'Cup motors qualify on something like 0W-5 - quite the reversal.

In the 18 years I've got on this Sideoiler, no one has ever asked me the pressure relief spring blueprint spec on a '67 NASCAR Sideoiler. I am fortunate to have gleaned this gem of antiquity from so esteemed a source.

[Anthony]

If I had to do it over again, I'd probably use a standard volume pump but with a 100 psi bypass spring, and leave the rear pressure relief valve in place.