quote:
Originally posted by over50:
... to me the oil pressure seems to be very high, especially with 10W30 oil. I've seen some references to a 50 psi relief but mine must be higher.
The standard oil pressure control spring in the Cleveland is set for 60 psi +/- 10 psi. What this means is that the pressure relief valve is fully closed at 50 psi, and fully open at 70 psi. This is a higher pressure specification than any other Ford V8, indicating the folks at Ford knew they had a lubrication problem.
The 351C is equipped with a hi-volume oil pump from the factory. The oil pump rotor is taller than in any other Ford V8. This is another indication that the folks at Ford knew they had a lubrication problem.
In spite of these measures most Clevelands have a hard time making 50 psi hot oil pressure (measured at 2000 rpm). This is due to leakage via the tappet bores and the over-sized clearances of excessively worn rod bearings. For the last 2 or 3 years of production the hot oil specification was 45 psi at 2000 rpm ... even though the pressure control valve was fully closed at 50 psi! This obviously indicates the folks at Ford knew they had a lubrication problem.
When a high pressure oil pump spring is installed the cold oil pressure usually runs ridiculously high, like 100 psi or more. Enough to burst an oil filter if the owner inadvertently blips the throttle while the engine is heating up. Following is your description from your first post:
quote:
Originally posted by over50:
... Installed mechanical 0-100 psi oil pressure gauge in passenger compartment. Tube comes from rear of engine off tee with electric gauge sending unit. Cold oil pressure is 70/75psi both idle and above. Even after water temp is up to 175 degrees, idle pressure is still near 70psi. When engine is fully warm, idle drops to 30/35psi and quickly increases with rpm to between 65/70psi ...
Based upon this description your Pantera's engine appears to have tappet bore bushings installed, as the pressures you described are exactly what I would expect to see with tappet bore bushings, they indicate an engine that has "normal" leakage at the tappet bores and rod bearings that haven't been damaged or excessively worn by the lack of lubrication. The capacity of the oil pump is not being "over-taxed" and the pressure control spring is operating within its intended range.