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MBradbury MBradbury is offline
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Join Date: Jan 2001
Location: Troy, Michigan, USA
Posts: 62
Question Conrod rocking. Is this normal?

Help everyone,

This engine rebuild is racking my nerves

I just closed the crankcase a few days ago, and now I am really concerned about the amount of rocking movement on all the conrods. The crankshaft was not reground, but I took extensive measurements with an engineering micrometer and it was absolutely within standard specifications with no measurable out of round. The old bearings were in near perfect condition when removed. I fitted new standard Glyco bearings, but DID NOT perform the plastigauge clearance check. I did perform the visual drop swing test, and they all seemed ok. Now the crankcase is closed, I can deffinitely rock the conrods. At first I thought it was lateral movement, but now I am convinced there is a distinct sideways rocking when I apply a finger-thumb force.

The only variable I can attribute is a temperature difference of about 20F between when I assembled the crankshaft and today's test. I don't know the exact coefficent of expanison of the crankshaft journal, but working on an average of 0.000008" per degree F, I can't believe this would account for the rocking motion.

Is it normal for the conrod to rock to the extent that you can feel a distinct click? Has anyone observed similar? If the experience of this board is there should be no rocking, I am prepared to spilt the case again and perform the plastigauge test. I wish I done it the first time

Mark Bradbury
1983 911 SC
Old 11-05-2003, 06:20 PM
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