I am rebuilding my 29 Plymouth engine (SN U50105). My car was manufactured approximately May 15, 1929. On this engine, the line to the oil pressure gage comes off an oil galley port on the left rear of the engine under the starter, near the rear main bearing. I obtained a 1929 parts engine (SN U29287) that was manufactured earlier than my engine. On this earlier engine the oil line to the oil pressure gage comes directly off the oil pump. I am using oil pump from the parts engine on my rebuilt engine. This has allowed me to place a second after-market oil pressure gage in my car, with the "new gage" showing the pressure at the pump, and the original gage showing the pressure at the other end of the oil gallery. When I run the engine, the difference in oil pressure between the two is 5-10 lbs when running at operating speeds (30-40 mph). At warm idle the two register about the same (~20 psi). Also, the gage measuring the oil pressure at the pump fluctuates quite a lot, while the oil pressure measured downstream on the original gage is much more steady. Now - I am trying to set the engine oil pressure. The "May 1929" manual states the oil pressure should be 35-40 psi at normal operating temperature. I have set it so the oil pressure at the original downstream gage is 32 psi when warm, and the pressure at the gage is about 38 psi. When the engine is cold and run at 30-40 mph, the pressure at the pump is about 45 psi - until the engine warms up. I hope this is OK?
My survey question is:1) What year is your car?
2) Where is the oil pressure line connected - to the oil pump or to the oil gallery under the starter?
3) What is the max oil pressure when run at operating speeds - cold and hot?
John