Good point Denny.Quote:
Originally Posted by DennyW
Logic would tell you that it would only increase pressure on the top but, that wasn't my experience.
I built my mtr pretty loose and the pressure would get down as low as 5 psi when hot at idle. But after shimming the spring it held around 15.
With the coil spring, I don't think the valve is an all or nothing valve. If the spring is a little weak, it will open a little even at idle.
For those that don't already know, Chevy's use a bypass oil system that bleeds some oil off to the oil filter through the check-ball valve in the oil pump. Ford use a full flow system that routs all oil through the filter.