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MG MGB GT V8 Factory Originals Technical - Adjusting oil pressure w/Buick 'Metric' oil pump?

Guys, my Rover 4.2 has the "METRIC" oil pump (Buick V6?) which I've seen on many other BOP/R V8 conversions. Query thus: my understanding is that it is easy to adjust oil pressure on these. If so, please tell me how. Additionally, when it is proper to change out the pressure relief valve spring for a stronger one? What's the optimal oil pressure for a Rover?
David

Various springs are available which will change the opening (or closing?) point of the pressure relief valve, which is part of the oil pump. When doing the mods to my oil pump to make it a high volume pump, the kit from Melling contained several springs of different strength & color. Using the recommended spring resulted in 100 lbs of pressure at idle, pegging the gauge while running. Far too much pressure. After experimenting, I finally went back to the old, used stock spring originally in the pump. Idle pressure, hot, 800 rpm's is around 25 lbs, hot running at 2000 rpm's is around 45 lbs. This is on a 4.2 that now has around 250,000 miles- same pressure as when new.
Jim Stuart

Oh. That is about the OP that I already have. It's about 48-49 going down the highway. If that's enough, I'm more than happy to leave well enough alone. Many thanks.
David


The Buick oil pump pressure can also be varied "shimming" (ie adding shims of various thickness under the pressure relief springs).

This achieves the same result as changing the spring and is often used for old or tired springs to maintain the pressure.

By the way most V8 engines run oil pressures of about 10 PSI per 1000 RPM minimum as avery basic rule of thumb.

Cheers, Pete.
Peter Thomas

Remember, its not just a question of pressure, VOLUME is the weakness of the buick oiling system. The longer gears of the oil pump kits also increase the VOLUME.
stevem

Also if you are going tot he trouble of upgrading the pump make the most of yor investment and have the internal oil galleries relieved to get the flow withing the block up to the same level.
Cheers, Pete.
Peter Thomas

This thread was discussed between 21/10/2002 and 24/10/2002

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