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The bearings in the D4600 are not the same as modern steel backed shell bearings. They are some form of aluminium alloy and they are at least 1/4 thick. The only problem I can see with using the bearings again is the fact that the crankshaft journals have been polished. Keep in mind that these engines are not high revving and only very low horsepower for their size.
After looking closely at my used rod bearings last night, I'm pretty sure I'm going to have to get the crank turned. Some of the used bearings look new, others are a little grooved and scuffed. I'm going to measure the new bearings inside the rod end with an inside mic tonight and see where they come out. In hindsight, maybe I should have done all this measuring prior to assembling. But when you are installing brand new bearings and your crank measures within spec........
I went through the effort of getting new bearings to zero-time the rotating assembly. As I think things through, it would be pretty stupid to do all this work to the bottom, re-do the heads, etc., and then throw sketchy rod bearings back in. Measuring the bearing bores in the torqued rods may tell you something. A dial bore gauge may be better than a hand mic. It is easier to see the out of round. I have no experience with all aluminum bearings so will not comment on how much clearance is needed with them. You mentioned the slight wear on the old bearings. Your fingers can feel .0005. Do you have any specs on what the thickness of the bearing shell should be?
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