Synchro909, would you mind posting a photo of how you did the relief valve?
It's inside the engine on the side of the oil pump so sorry, no.
It is a piece of steel rod that I put in the lathe and turned on end down to 9.5 mm (3/8"). I then put a 3/8" UNF thread on it and drilled the larger diameter to (by memory) 11mm. After checking what springs I had on hand, I calculated and measured how long I would need the tube to be. I then tapped the other end to take a plug. I made a 11 mm diameter piston which went into the tube followed by the spring. I calculated how much force was generated by 22-24 psi in a 11mm dia. tube. I screwed in the 11mm plug and then put a nail up the tube from he male thread end and used the kitchen scales to get the force I had calculated. After a couple of trial and error testes, I had something I could work with so I measured where the piston was. That gave me where to drill across the tube for oil to escape through once it reached 22-24 psi. After cleaning up the burrs on the inside of the tube, I assembled it and checked, adjusting the force to get the piston to where I could see the piston just start to uncover the cross drilled holes when the scales told me I had the right force on the piston. The female 11 mm thread and plug gave me the ability to adjust it. Once I was happy, I drilled through the plug and tube and inserted a split pin. I drilled and tapped a hole in the side of the oil pump where Terry said it should go, screwed the valve in and put a couple of weld tacks on it to hold it.
The valve points directly across the engine so it clears the counterweights and blows relief oil into the dipper tray and upwards.
I was pretty much spot on. Cold, with 20W50 oil, it sits on 22-23 psi and when thoroughly hot, 19-20 psi. About 4 psi at idle.
I don't know whether it actually passes oil or whether the modified A pump can only deliver that pressure given there are so many bearings to bleed off the pressure.
I hope you can follow that but if not, PM me and I'll make a drawing and send it to you. There is a warning though. The drawing will look like I did it with a thumb nail dipped in tar. (That's a reference to a famous Australian poem, Clancy of the overflow.)
