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crankshaft bearings
Topic Started: Oct 17 2013, 07:53 PM (663 Views)
geodad98117
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Just got my '98 G10 engine back from the machine shop, it looks beautiful! They surfaced the head and the block for flatness, did a full valve job and bored .5 mm over. The crank was within specs so they just polished it and ordered up a set of standard bearings, they got Clevite brand which I can say, for my crank, is a perfect fit. As always, your mileage may vary.

I was warned that aftermarket bearings can be slightly undersized so I checked several of the journals with plastigauge. They were all right at .001" which was a huge relief. It's a real simple process to check and I'd highly recommend if you're worried your clearances might be out.
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evintho


If you don't mind I'll add some pics to this thread. I'm in the middle of rebuilding mine and I just happened to snap some pics when I checked the clearances with plastigauge. Very simple process. Lay a strip on the journal, install bearings and torque down a cap, remove cap, measure with the enclosed gauge. If the machining was done right, it should be right on the money!

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geodad98117
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evintho
Oct 17 2013, 11:35 PM
If you don't mind I'll add some pics to this thread.


Thanks, don't mind at all. I was thinking I should have taken some pictures to show how simple it is.
Edited by geodad98117, Oct 17 2013, 11:49 PM.
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socal geo garage
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.001 to .0019 is the spec from the gm service Manuel the green plastigage measures small so you are a bit tight, take it back and have them polish it down a bit. up to you if it was mine i would take it back with the strip on all 3 and have them adjust to 1.4 for nice quick revs & MPG ....could Bind on you torque mains and rod bearings without piston rings and see if you have ANY binding at all.
Edited by socal geo garage, Oct 18 2013, 12:20 AM.
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Smidgen
Smidgen

it looks like you used the red stick and measured with the green paper. As far as I know you cannot mix and match. It looks like you are closer to .002.
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geodad98117
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Smidgen
Oct 18 2013, 12:52 AM
it looks like you used the red stick and measured with the green paper. As far as I know you cannot mix and match. It looks like you are closer to .002.
That's good info to know. I was wondering why his stick was red, mine was green and I have the green gauge strip. That brings up another question I had with this procedure.

I was thinking if you put a strip on just one side on the rod journal it would show overall clearance. This would mean that with the clearance distributed uniformly it would be one half what the reading shows. I looked up the plastigauge website for direction and it said on large bearing surfaces to use 2 or 3 sticks distributed around the journal. I put one on the top of the journal and one 180 degrees opposite on the bottom. Torqued it down and pulled it apart. It showed .001 on both sticks.

So if evintho is reading .002 on one side of his connecting rod journal, wouldn't that clearance be distributed as .001 all the way around?
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