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Is this a worthwhile thing to do, or leave them as is? Reason I ask is because I've seen erosion between the galley holes in the bearing saddle, so wondered if slightly increasing one or both of the bearing holes would help. In the pic it looks like they opened it to match the galley size, which seems like it would be too much.
 

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What I do instead is slot the block to match the slot in the bearing, you can do it with a cut off wheel. It allows the oil to flow into the bearing through a larger area than just the window of the main oil feed passage and is much less of a pain than drilling the bearings and you don't have to do it every freshen up like you would if you modified the bearings.
 

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One thing I discovered when using a Dart block, is that Dart spread the two oil feed holes in the main saddle apart!

The four non-thrust bearings had a long enough slot that it was not an issue, but the center thrust bearing had a shorter slot than the rest, and the primary oil feed hole was almost blocked off. I had to elongate the slot. That being said, I later checked a newer set of King bearings, and all of the slots were long enough.

It's definitely something to check if you have a Dart block!

DART:


FORD:
 

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As far as the erosion, I had some erosion/pitting on my bearings after making dyno runs then letting it sit for a few weeks before tearing it down, the lad at the engine shop said it was from fuel in the gas and said he'd get better or harder bearings. Not sure if thats what your seeing or not.
 

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I have been doing that bearing mod to Pontiacs since the early 90's. ;)
Oil feeds at n angle and the oil hole faces the cam bearings. Nothing like making left and right turns to lube the crank and rods.
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BTW; I can't remember anymore but there is a company that makes slotted main bearings for the 302 Ford engine. Used them a lot before i retired.
 

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Is this a worthwhile thing to do, or leave them as is? Reason I ask is because I've seen erosion between the galley holes in the bearing saddle, so wondered if slightly increasing one or both of the bearing holes would help. In the pic it looks like they opened it to match the galley size, which seems like it would be too much.
What Stuska said is best advice. We place the block on a milling machine and machine a slot in the main saddle using a carbide ball endmill. Like he said, do this one time and you don't have to fool with the bearings every rebuild.
 
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