Engine Installation Thread

[jaredyates]

I found that most threads on the engine are coarse, and grade 5 hardware from the local place works great.

[Bcone1381]

I found that most threads on the engine are coarse, and grade 5 hardware from the local place works great.

Those course threaded bolts are sometimes hard to find for some reason on typical aircraft hardware sights. AN bolts are fine all threaded.

With that being said, I am begning to like Studs instead of bolts that thread into cast aluminum. Consider them instead of a bolt. Aluminum castings receive the stud once and stay put. A bolt is removed & installed untold number of times and that can create thread wear in the aluminum casting. As a datapoint to confirm my theory, both Lycoming and Continental parts manuals have studs with oversize threads to accomodate the looser fits.

[alaskabearhawk]

AS sells the coarse engine bolts with drilled heads. They are MS20074 series: https://www.aircraftspruce.com/catal...inebolts15.php

Also do a search for "MS20074 Bolt" on ebay. I found quite a few on ebay that I needed and they are much cheaper than the normal aircraft hardware suppliers. I'm guessing you need four MS20074-04-04 bolts.

[noema]

Thx Bcone1381, alaskabearhawk! Ordering the MS20074-04-03. For some reason I found the ACS page but didn't realize that the coarse pitch screws are listed further down. I guess studs would work too. Actually my Lycoming came with some long bolts the could be turned into studs with a safety wire hole at the bottom. (supposedly for the baffles or mounting other stuff).

[svyolo]

I will concur with Brookes on using studs if you can in Al. AL threads are pretty easy to bugger up.