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145 Posts
This all started when I tore the pan down a year ago, maybe more, to replace a leaking base gasket. It's a 1959, unmodified. Found the rear cylinder and piston scratched beyond repair. Bought new V-Twin cylinders (gulp), sent the heads, cylinders, pistons to Accurate for bore and rebuild, all new, and went back up. Put a pressure gauge on it this time, for good measure. I was sure the failed base gasket was the source of the ruin, as it failed on the pressure feed hole to the top end (common failure).
As it warms up to full hot, takes about 20 minutes, the pressure gradually falls off to zero with the stock, cast iron oil pump. Me and the wrenches I hang with eventually settled on tired pump, so new S&S pump, installed last weekend. Guess what, exactly the same deal, exactly, no change. 40-45 psi on cold start, holds good pressure early then just graaaaadually fades to nothing at full hot. I'm talking about nothing here, not even a blip when I jack it. One interesting fact, that may be important, is that when the lifter screen stops up, which it's done three or four times since the build, it holds great pressure, 25-30 psi, in the bottom end, even at full hot. Clean the screen, same deal, pressure good early, then fades to zero.
S&S is stumped, I'm stumped, my wrench friends are stumped. S&S suggested I go back to solids and plug off the hydraulic feed holes, which I had already decided to do, but what do you guys think about this? Any help or opinions would be greatly appreciated.
As it warms up to full hot, takes about 20 minutes, the pressure gradually falls off to zero with the stock, cast iron oil pump. Me and the wrenches I hang with eventually settled on tired pump, so new S&S pump, installed last weekend. Guess what, exactly the same deal, exactly, no change. 40-45 psi on cold start, holds good pressure early then just graaaaadually fades to nothing at full hot. I'm talking about nothing here, not even a blip when I jack it. One interesting fact, that may be important, is that when the lifter screen stops up, which it's done three or four times since the build, it holds great pressure, 25-30 psi, in the bottom end, even at full hot. Clean the screen, same deal, pressure good early, then fades to zero.
S&S is stumped, I'm stumped, my wrench friends are stumped. S&S suggested I go back to solids and plug off the hydraulic feed holes, which I had already decided to do, but what do you guys think about this? Any help or opinions would be greatly appreciated.