Oil pressure relief valve booster spring

[Duncan M]

So far the engine in my TC that was packed away in 1955 or '56 by my father is continuing to amaze, as the car gets driven around for longer and longer drives. The other day I decided the oil pressure was just too good to be true. Upon removing the oil pressure relief valve assembly, not only was everything getting cleaner by the mile, but the ball bearing had no grooves or wear of any kind. Of interest was not just the original 13 wind spring, but also what has been identified as likely BMC part # 706/226 "oil pressure booster spring." Also 13 winds. Apparently these have been NA since the '70's. Any reason not to keep running this?

[Steve Simmons]

What kind of pressure are we talking about? Generally speaking, 10PSI per 1000 RPM is fine. XPAGs seem to run a bit lower than more modern engines like MGB. In my opinion, anything between 40-65 PSI at highway speeds is good. Higher than that and I'd lower it a bit. If you're in that range with two springs then I don't see a reason to change anything.

As for the ball, I doubt it sees any real abuse that would wear it down. It doesn't spin or anything, just moves slightly up and down and is always immersed in oil!

[Duncan M]

I think I will try the standard spring only.

[stephen stierman]

I rebuilt my xpag about 11,000 miles ago and it included new cam bearings, crank turned with new rods and mains, etc and will see around 60 lbs at road speed hot, much better than it was prior to rebuild with about 20 lbs. hot give or take.