OK I picked up a 67 Special with the 300 in it and the oil shaft pump is EXTREMELY hard to turn the motor does turn freely with the breaker bar, my question is how hard would it be to change the oil pump with the motor still in the car?
Let be a little more specific what is involved in performing this procedure? Is it highlighted in a sticky?
Most Buick engines, with the exception of the Nailheads, have the oil pump in the timing chain cover. It is driven by the distributor via the cam. The pump is actually 2 gears that rotate in a pocket that is integral with the timing chain cover. One gear has a shaft that extends up to the bottom of the distributor shaft. The other gear rides on a pin. The timing chain cover is aluminum, the gears are steel. The cover expands more than the gears when hot. That increases clearance in the pump. Clearances are critical to good oil pump performance. If the timing chain pocket is worn, oil pressure will not be as good as it can be. End clearance between the gears and oil pump cover should be set at .002-.003. This is done with the right gasket. Put "oil pump end clearance" into the search function of this board. It has been discussed many times before. To disassemble the pump, remove the oil filter. Remove the small bolts holding the pump cover/oil filter nipple to the timing chain cover. Pull the gears out and inspect the pocket for wear. When you re assemble the pump, pack the pocket with vaseline to fill all air spaces around the gears. This ensures the pump will prime upon start up.
