lml@lancaironline.net Mailing List Archive

Bob--

Thanks for all that, especially the timely warning on the stainless steel nuts; I haven't installed them yet so I'll use the chrome-moly nuts instead.I had planned to use anti-sieze compound on the studs, but that probably would have just burned off.

--John

On 11/25/2013 3:09 AM, bob mackey wrote:

I also switched to 12-point reduced diameter "K-nuts" for my Lycoming exhaust.

However, I would strongly advise against using stainless steel. It will gall and weld to the stud, then the stud will come out with the nut. If you're lucky. If not so lucky, the stud will break off.

I used a black-oxide chrome-moly steel flange locknut from the aviation department at McMaster Carr.

Part Number 90759A200

Chrome-Moly Alloy Steel 12-Point Flange Nut, Black-Oxide, 5/16"-18 Thread Size

http://www.mcmaster.com/#nuts/=pj23uv

Before I switched to the 12-point nuts, I used a 1/4 drive socket ground down to fit into the space. the socket depth was cut down so that it just engaged the top 1/8" of the 1/2" hex nut.

BTW "standard" 5/16-18 hex nuts fit a 1/2" wrench. If your nuts need a 9/16" wrench, they are "heavy" nuts.