This issue has me completely baffled. Car is a 1968 Series V with correct 725. New engine rebuild with some mods, none of which should effect oil pressure.
New bearings, (main, rod and cam) oil pump etc. Engine started easily - oil pressure at cold idle was about 40 psi. When engine got fully warmed up this fell to 10 and below.
Modified the pressure relief valve to make it adjustable. Now cold pressure at idle is 60 to 80 - basically whatever you want to set it to. Now hot idle still drops to 10. Changed oil three times, the last time we put in old school Valvoline Racing 20-50. No real difference. When driving the car, pressure initially goes up to about 40. Then as the engine gets fully up to temp it drops down to 15-20 at 5,000 rpm. For a new engine this is really not good.
I've built many engines over the past 50 years, however this is the first Alpine. Never experienced this issue before. Pulled the engine back out of the car and disassembled to check. Bearing clearances on mains and rods are good. Oil pump clearances are tight. I am stymied.
Are there any secret oil galley plugs that I might have left out? Only one that was odd for me was the timing chain squirter and I even crimped the end leaving only the small hole to feed oil to the chain and gears. It has the small ball and spring installed as called for.
Car owner has been extremely patient but I am at my wits end. Any members out there ever experienced this problem before?
Henry Payne
HPMotors
New bearings, (main, rod and cam) oil pump etc. Engine started easily - oil pressure at cold idle was about 40 psi. When engine got fully warmed up this fell to 10 and below.
Modified the pressure relief valve to make it adjustable. Now cold pressure at idle is 60 to 80 - basically whatever you want to set it to. Now hot idle still drops to 10. Changed oil three times, the last time we put in old school Valvoline Racing 20-50. No real difference. When driving the car, pressure initially goes up to about 40. Then as the engine gets fully up to temp it drops down to 15-20 at 5,000 rpm. For a new engine this is really not good.
I've built many engines over the past 50 years, however this is the first Alpine. Never experienced this issue before. Pulled the engine back out of the car and disassembled to check. Bearing clearances on mains and rods are good. Oil pump clearances are tight. I am stymied.
Are there any secret oil galley plugs that I might have left out? Only one that was odd for me was the timing chain squirter and I even crimped the end leaving only the small hole to feed oil to the chain and gears. It has the small ball and spring installed as called for.
Car owner has been extremely patient but I am at my wits end. Any members out there ever experienced this problem before?
Henry Payne
HPMotors