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Old Apr 04, 2015, 12:24 PM
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OS Gemini Cam Bearings

I have had to repair 3 different OS Gemini twins in the last few weeks . When stripping them down it was obvious that all of them had quite a bit of clearance in the cam bearing assemblies . A couple of them were at .010 " clearance per side .
All of the engines were rather low time engines and it seemed that the bearings were very prematurely worn .
Has anyone else seen similar results ?
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Old Apr 04, 2015, 06:39 PM
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This is interesting. I will be doing bearings in my FT-160 before flying this season so I'll have a look. How did these engines look inside otherwise?

Greg
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Old Apr 04, 2015, 06:55 PM
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Thank you Greg , I was hoping to hear from you .
One of the engines had lost a con-rod but looked great otherwise the other two were crash damage but the innards aside from cam bearings were very nice on the inside . Two were synthetic oiled , one had some castor residue but no real rust issues .

They all had similar cam bearing clearances on both ends of the camshaft . By measuring over the bearing bore with the OD I saw about .24 MM clearance per side ! Just a rough measure but still a lot of slop !
Please let me know what you see in your engine ,
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