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Discussion Starter #1
Somewhere I read it is a good idea to grind shallow oil grooves in the connecting rod bearing surfaces to promote oil distribution, an X in the top and bottom halves. (not in the crank shaft!)

Does this make sense or is it out of line?

The current Tecumseh connecting rod has an oil feed hole at the top. Otherwise, the bearing surfaces are flat. One motor shows a tiny bit of galling on the connecting rod surface. I am thinking a little better oil distribution could have prevented that.
 

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Nope, dont mess with it...rods have whats called oil clearance, and if there is oil anywhere on the rod, it distributes evenly around the journal.

Galling on the top of the rod journal is usually caused by overheating, or overworking the engine, with bad, thinned out oil, or low oil.
 

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The law of unintended consequences definitely applies. Don't try to outsmart the factory engineers unless you are smarter than they are.
 

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Discussion Starter #4
OK, no changes. That makes it easier. Thank you.

Then it's ready to re-assemble and (gulp) test.
 

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The hole in the connecting rod is actually a squirt hole intended to lube the cam and lifters/tappets. That is if it points towards the cam...
There should be a hole in the connecting rod bearing journal that supplies oil to the connecting rod. If you have a pressure lubed system.
I have seen grooved bearing shells, but mostly main bearings, and some camshaft bearings. They are generally there to allow oil to feed further on in the system, using the main bearing supply as the supply to the hydraulic lifter gallery, for example. The groove allows oil to pass right on through to another hole in the bearing shell feeding the cam or lifters or what ever.
If you were building a race engine, there are other things you can do to plain bearings to make them handle the heat rejection and bearing loads better. I have heard of the bearing shells being cooked and frozen to change the texture of the bearing surface. They wanted to get a 'bumpy' surface, with lots of highs and valleys to minimize contact and maximize flow, I guess.
tom
 
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