Hello all,
I just checked in the factory manual for my 1985 S15 pickup truck, and in the R4 overhaul section it does rather clearly state in the R-4 compressor front head and/or O-ring section page 1D1-18, (REPLACE, Par 3) "Position the oil hole in the Front Head to be "UP" when assembled to the compressor cylinder to correspond with the "UP" position of the compressor. Install the Front Head and tighten the front head mounting screws to 27 N'm (20 lb. ft.) torque."
There is also a picture that shows the oil hole. The front bearing is a needle bearing, and the front head is held on with 4 screws. Seems to me that it would be a simple thing to rotate the front head to the desired position before installing the compressor, it might be a good idea to use a new o-ring. The only problem is that one would have to pull the clutch and clutch coil off the front head to get to the screws.
So here's the dilemma- the oil hole really doesn't have any oil collection surface, so does it really matter if it's up or down? If it's down, the oil will enter the bearing area along the shaft surface and leave from the hole, if it's up the oil will enter through the hole and exit from the shaft surface. There's not really that much difference in my opinion. But, it appears the information given is correct.
Regards,
Richard Wooldridge