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Help with tolerance for IO360 case studs

mandorfer

Active Member
Help. I have looked in the table of limits and multiple IO-360 assembly manuals and I can't find the diameter tolerances on the long 0.500" studs (Lycoming 75154 or 72154) that pass through the case. Does anyone have a reference for that? I am about to reassembly the engine and want to make sure they are correct. Thanks.

Mike
 
I check the fit with a plug gage or use a thru bolt. If its not an interference fit I order oversize thrubolts.
 
Body-Fit Through Bolts

?Interference fit ? They need to go in solid if you can push them through by hand they?re too loose. I often have too use P-1 ( .001? oversized) through bolts in some locations with the center main ( 4 cylinder ) being the most critical. I watched an engine builder at a big name shop using a custom slide hammer to pull through bolts out of a recently built Lyc 4 cylinder. When queried the builder told me they can?t be too tight.
 
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