Re: Deja Vu

Posted by Tim Cole On 2011/11/19 16:27:53

Hi Folks:

I'm not sure why choosing tiny teeth on gears that are clearly oversize represents an engineering advantage, except that perhaps the horsepower load is decreased, and that oil pressure in a worn motor may be more stable.

What I do find very interesting is the comment that
number 8 rod bearing was the first to go. This is the bearing closest to the pump. It has also been the bearing that I have seen spun most often. In the Senior 8's number 2 is the rod that likes to go into orbit and is nowhere near the feed source.

When I look at the pump circuit for the V-8 the feed for number 8 rod bearing is directly taken from mainline pressure before the sender. The other rods are being fed from the oil gallery. Now to do this the oil has to change direction and if you get the mainline flow going fast enough this can create a syphon action that will starve number 8 rod bearing.

So maybe this Oldsmobile pump with fewer teeth leaves a few milliseconds of reverse pulse that interrupts the tendency toward suction and therefore rod bearing failure. The bonus for the lifters maybe that there is less aeration of oil with the larger teeth.

How about that?