Worn Rocker Arm Washers - what else?

[Lucky Phil]

 

Two comments here. A) test rig should simulate the environment that the components work in. Substituting air for oil is a no go. Air just removes the oil that is part of the system. Use air to pressure an oil tank that feeds the test rig, your results might change.  2) Lapping? While I haven't had this system out this is a piston in a tube with radial holes at a determined depth. The piston balances oil pressure (low side + spring pre-load) vs the high side (mechanical oil pump pressure.). What was "lapped" the piston to the bore?

 

Scud, here's how the pressure relief valve works. This is a small block PRV from the Aero engine conversion, but they work the same..

Nothing but a piston closed by a spring. The washers control spring pre load. 

Simple.. but..

Here's a quicky test rig I made up. Pressure is controlled by an unseen regulator. The Lario PRV blew off at 20 lbs. (!) Washers made very little difference. I used some fine lapping compound, and lapped the piston into the orfice. Viola! 75 lbs. 

Need I say to clean the lapping compound out very well? 

I would look here, first.

 

Wrong on both counts, perfectly adequate test using air, crack pressure is crack pressure at 60psi oil or air doesnt matter. If you were interested in the flow rate after it cracked then it would.

No its a straight piston and spring,pump pressure one side crankcase pressure the other,so for all intents and purposes its spring preload that determines the crack pressure

Ciao   

[Chuck]

Thanks, Phil..

[Scud]

The oil-pressure puzzle is solved. I posted the below in the thread where I originally brought it up, but wanted to "Close-Out" this thread too.

 

A piece of the upper sump gasket was missing. It was one of the two tabs that goes between the housing for the filter and the block - it was metal to metal contact at that point (where the oil was supposed to pass through under pressure. The lack of gasket created a substantial, pressure-robbing, internal leak. After finding that problem and installing a new gasket, I have much higher oil pressure - about 40 PSI at 2,000RPM and holding steady at about 60 PSI under normal riding conditions. 

 

Thanks again to everyone in this thread.