Oil pressure sending unit

1 Kilogram force per square cm = 14.22 psi, so yes, 64 psi. What happens though, due to wear and internal oil pump clearances, is that when the oil and engine get hot, idle pressure can drop below 7 psi, and that is when the light turns on. I suggest you take the car for a long ride at highway speeds for 15-20 minutes, then stop and check the idle oil pressure.

 

No, you can't relax, I wouldn't. Get the engine good and hot and measure the oil pressure at different RPM. The light turns on at around 7 psi. That is not good, but at idle, nothing will be hurt. The pressure should rise as you raise the RPM. The 400-430-455 engines need a minimum of 10-11 psi for every 1000 RPM. The chassis manual says normal hot oil pressure should be 40 psi (2.8 kgf/cm2) at 2400 RPM. If you have 20-25 (1.4-1.75) at 2000 RPM, and 30-35 (2.1-2.46) at 3000, that is OK, but still low. If you want to rev the engine to 5000 RPM, you better have 55-60 psi. (3.8-4.2)

 

The oil pump consists of 2 gears rotating in a pocket that is part of the timing chain cover. One gear is driven by the bottom of the distributor shaft, and that gear drives the other. The clearance between the gear teeth and the sides of the pocket, and the gear faces and the oil pump cover is critical. As the engine heats up, the pocket expands and clearances increase. As oil gets hotter, it's viscosity decreases. It is normal for oil pressure to be high when the engine and oil are cold. It is normal for oil pressure to drop off as the engine and oil get hot. If clearances in the pump get too large, oil bypasses the gears and pressure gets too low. The clearance between the oil pump gear faces and the pump cover is called end clearance. The gear faces actually extend above the timing chain cover gasket surface. The oil pump cover gasket can be used to adjust the end clearance. TA Performance sells a gasket assortment meant for adjusting end clearance.

http://www.taperformance.com/proddetail.asp?prod=TA_1704

As the bottom of the pocket wears, the gears sit lower in the pocket. That increases end clearance. If the pocket is excessively worn, then the timing cover must be replaced. The chassis manual shows how to measure for end clearance,


Looking at the above picture, the gears should extend between .002 and .006" above the gasket surface. Preferred end clearance is .002" If the above measurement was .004, then using a .006" gasket would give the preferred end clearance.

TA Performance also sells a booster plate to boost oil pressure. That may also be an option.

http://www.taperformance.com/proddetail.asp?prod=TA_1510