flathead oil pump gear question

Started by Tom Martinez, July 29, 2011, 11:17:14 PM

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Tom Martinez

I'm currently fussing over the details of my 1941 346 engine rebuild and I'm working on the oil pump.  I received my new gears and shaft from Egge. After dry assembly I seem to have excessive backlash. the spec says .008"  to .012" thou. I seem to have about .014. The body checks out within specs (I'm using the tank manual), I have checked the sizing of all the details such as the shafts, bores, etc. everything is well within limits.

My old helical style gears are pretty scored up on the faces and they have maybe .018" so Just for fun I flipped my original gears around so the worn faces are no longer in contact, it was better but still the excessive backlash remains.
I'm checking the backlash just by using a feeler gauge between the teeth whilst holding one gear and rotating the other. I believe the actual measurement should be done at the O.D. of the gears with a dial gauge, but my crude method is close, and it would only be worse at the O.D.

What am I missing? Is my measuring premise wrong? do I have bad gears? should I just use what I have? I'm trying to build a strong runner, not a museum piece, hence the fussiness.

Any experienced opinions will be appreciated. Regards, Tom M.