Downside of shimming oil pressure relief valve in a 59A

[BigDan]

What problems could occur from shimming the oil pressure relief valve in a 59A, assuming no bonehead mistakes? What might the bonehead mistakes be?

Thanks in advance for comments.

[rotorwrench]

Shimming too much. The earlier engines didn't need as much pressure using the floater bearings. Many have been known to idle just a bit above zero and run out at 20 or 30 psi when outside air temps are high.

[G.M.]

The proper thickness shim to get the oil pressure you want will cause
no problems. Of course the pump has to be capable of producing 50
or 60 lbs. Even a shim that is to thick isn't a problem, the valve that
the spring pushes has a flat side removed on the side of the valve.
This flat allows oil to leak down on the timing gears to lubricate them.
On 37 to 48 engine some of this oil is slung off the gears to little catch
cups and into small holes that send non pressurized oil to the water
pumps. G.M.

[BigDan]

3/8 in about right for shim? I have the common problem of very low to zero pressure at warm idle.

Thanks.

[flatheadmurre]

Originally Posted by BigDan

3/8 in about right for shim? I have the common problem of very low to zero pressure at warm idle.

Thanks.

If the pump or bearing clearance are out of spec shimming won´t do much for the idle pressure.

[rotorwrench]

Sponsored Links (Register now to hide all advertisements)

Yea, if it's gushing past worn gears or bottom end bearings, not much will help with that.

[Kahuna]

I think a 3/8" shim is a bit much.
JMO
Jim

[flatheadmurre]

You can get 80Lbs springs for it to replace the old probably worn from use over a long time.
How much pressure the old bearings like can be debated.
When the flow on a bearing gets to high there is always a risk for wear from that instead.

[TomT/Williamsburg]

There's s 50 lb spring available as well ....

[G.M.]

Originally Posted by BigDan

3/8 in about right for shim? I have the common problem of very low to zero pressure at warm idle.

Thanks.

About 5/16" is about what you will wind up with. G.M.