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Builder’s Tip—Slim Wrench Needed for Engine Bolt
Bits & Pieces Newsletter - July 2014
By Ian Brown, Editor - Bits and Pieces, EAA 657159
July 9, 2014 - This tip might apply to other occasions, but was specifically necessary to allow correct tightening of the top left engine vibration mount bolt on the O-320 mounted to my RV-9A. The problem is that the pushrod tube on Cylinder 4 is so close to the end of the bolt that there is insufficient clearance without risking damage to the tube.
My solution was to grind off enough of the wrench (a spare one as it happens) to allow a good fit over the bolt, and to reduce just the part of the wrench to allow it to clear the end of the bolt and the pushrod tube. It was polished on the 3M Scotch-Brite wheel.
The clearance for between the nut and the engine mount really needs quite a slim wrench, too, so I ground off part of the diameter of the head of the wrench as well as its depth.
Finally, it’s not likely I’ll need that modified tool for several years, so labeling it is a handy reminder if I ever need to remember what I did last time.
It will also make it easier to identify if I want to lend it out for the same purpose.