the article linked has a lot of the background and the detail. However, be sure to note that the article is nearly 20 years old. As mentioned in the article folks ran 50 weight oil back then. That was certain to increase the loading on the small oil pump gear. The subject of oil pump gear failures surface time to time, but confirmed failures are really rare. Some of that is because many top level slant six racers have changed to belt driven external pumps and those that have not know to take care in the installation, verify that the gear alignment is good and some have added the extra oilers as shown in the article. The only oil pump gear failure that I have observed in the past 5 years was caused by a severe mis installation of the oil pump gear. It was pressed so far on the shaft that the mesh with the cam gear helix was out on the tip of the oil pump gear. Still it had ran several seasons that way.
