Reply To: oil pump drive

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For replacement gears, first try Then & Now Automotive in Weymouth, MA (AKA Antique Auto Cellar, best known for fuel pump rebuilding–see link). Clearance of oil pump end plate should be 0.002 (mine was 0.012 before machining inside surface). The two matched pump gears are more critical than the upper drive gear; the slop in the (upper) drive gear really doesn’t have much effect, in my opinion.

The drive gear is accessed via the square cast plate attached with 4 bolts and located at left rear of engine underneath manifolds. Oil pump is driven by a vertical piece of 1/2-inch square tubing (available at hardware stores) which, believe it or not, dangles from the drive gear assembly by a cotter pin! The oil pump drive has a tapered tip above the square section that fits into the square tubing to permit ‘threading’ the pump drive into the tubing.

Originally, the oil pump was secured to oil pan by 6 studs and nuts. I strongly recommend replacing those studs and nuts with cap screws to make it MUCH easier to ‘thread’ the tapered tip of the oil pump drive into the square tubing should you need to do so later when the pan is on (I found this out the hard way). Be careful–3 of the 6 threaded holes are blind or closed, so ensure that the cap screws are not so long that they will break the cast aluminum pan. I put flat washers under the heads of the cap screws and use Permatex #2 on the threads of the cap screws.