IO-540 Vaccuum Pad Stud Size

[Auburntsts]

Folks,
I want to add a standby alternator on my 540's vacuum pad but my rebuilt didn't come with any hardware for the studs. What' the stud size or the right metal lock nut to use?

 

[mahlon_r]

Should be 1/4-20 threads.
Good luck,
Mahlon

 

[Auburntsts]

Another issue

Thanks Mahlon for the info. A quick search of the usual suspects (ACS, Vans's, Wicks, etc) didn't turn up an AN 363-4 metal lock nut with coarse threads (20 vs. 28). Anyone have a suggestion? For those with vacuum pumps or alternators on that pad, what fastners are being used?

 

[rocketbob]

Tractor Supply is where I get course thread hardware for engines. Buy it by the pound there. The stuff you buy there is better (Grade 8) than what Lycoming uses (Grade 5).

 

[rleffler]

I've been able to get some from NAPA in the past as well.