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Guest Anonymous

New main bearings very tight... after losing all oil I po

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Guest Anonymous

asking for advice last week what to check out. The crank looked beautiful still good polish almost no wear from orignal(and I miked it). The main bearings had slight wear and the con-rod bearings looked like they had spun. I tore it down and cleaned everything out and put in new bearings (std. main and con-rod). I plastigaged the assembly and everything ceheked out. I assemlbled everthing using STP as assembly lube and the engine is so tight it won't turn. It make no sense, I went through everything twice connecting rods point the right direction caps on right, checked torque. But it is so tight it will not turn even when the car is rocked in gear.

Thoughts, suspicions, things that go bump?

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Guest Anonymous

It should be very easy to turn...with a torque gauge only inch pounds to turn it..

Are you sure you put the bearing shells in correctly...

(the tabs are pointed correctly) are the caps on perfectly straight??

Either you ended up with mismatched bearings or you did something wrong on assembly..

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Guest Anonymous

I agree with the statement it should be easy to turn. I have re-measured the bearings, diassembled and re-checked orientation of caps and put it together again. Still very tight.

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Guest Anonymous

I cant see why it would be a problem but.....

does it turn fine with only the mains in place (no connecting rods attached?)

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Guest Anonymous

Rod,

Double check that the rod bearing caps are on in the correct orientation. If you reverse one, you can throw the bearing tolerence off. (due to the way the big ends are ground)

If this doesn't help seems like some step by step troubleshooting is in order. First take off all the rods and make sure the crank spins over nice and smooth...then add one rod at a time. The whole rotating assembly should move smoothly with the exception of piston ring drag. If you are truely anal, assemble the bottom end sans pistons and make sure they turn then take it apart again and assemble everything.

Really good engine bottom end cranks will spin freely with no rods on them and just the main caps. I'd suspect orientation or some other misassembly problem. The m10 that I just built for a friend turned over easily with no problems, but when I was plastigauging the rods ends, I put a rod cap on backwards and the rod refused to budge on the crank.

Also check the thrust bearing clearence on the crank. Sometimes when cranks are redone the thrust clearences are not increased for the oversized bearings.

Goodluck

-Bernard

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Guest Anonymous

Nick referred to this. The little cut out area on the end of each bearing half should be opposite each (180deg out) and not on the same side. If they go in wrong the motor will not turn over. Weird, but true.

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Guest Anonymous

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I know it is too late now, but maybe you could undo them one by one until you find the culprit.

Do NOT rock the car please. Use a ratchet and a 30mm socket available for $8 at any Pepboys store. It will let you feel when and where it gets stuck. You may have to remove the fan blade but it will make your life way easier. Trust me.

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Guest Anonymous

your crank may be tweaked or mains are out of alignment

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