Hi
I just opened the box of new inserts for my P-24; Federal-Mogul kit #485.(M10)
The same six inserts are supplied for the two center mains and the front. These fit the front, but not the center two locations. They are wider, and the oil holes don't line up. The parts book, and my old parts show the center inserts to be the same as each other, but different from the front and rear.
What gives?
Mr. Cranky

I did a 230 a couple of years ago. I don't remember about the bearing width of the two center mains. I do remember that the oil holes do not align properly. You should make the align by either relieving the block or redrilling the bearing. I relieved the block to make the holes align. Oil flow at the two center mains is critical. Each main has to furnish two rods with oil. This is where usually rod burn out occurs. I had my crank cross drilled in this area. So far I have had no rod bearing damage in this area. Hope this helps.

The misalignment isn't difficult to correct, and I've seen it on a couple of other older engines of various manufacture.

I'd like to recommend that you use a sharp round file to open up the bearing hole in order to match up the passages. Then carefully chamfer it with sandpaper like the crank holes. The reason behind this is due to the possibility of oil pressure literally pushing on the back of the bearing. If there is enough bearing area sticking out into the hole misalignment, and the oil pressure is high enough, there can be problems with premature wear on that part of the bearing face around the hole.

Even though it may not look like much area hanging out over the hole, the net effect from the physics of "pressure times area equals force" is no different than if a small piece of crud (metal, dirt, etc.) is left between the bearing shell and the block when you assemble the parts. It will create pressure where it's not supposed to be and result in excess friction.

The only apparent issue with this method is the "large" hole, and the apparent lack of support for the crank due to the missing shell material. But that "hole" is filled with pressurized oil when it's running, and the crank is supported on the hydraulic pressure, instead of the pressure pushing on the backside of the bearing and squishing the oil film down too thin on the crank side.

I hope this helps out, too.

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David
newbie #4153

Mystery solved; the Parts Kid gave me Slant Six parts!
Ward