Changing out studs

jdeas · #1 06-03-2010, 03:12 PM

While mounting the exhaust and MT governor on my IO-360B1B I ran into problems with the stud lengths.
It appears that I need to purchase longer studs for the governor due to the thick MT base plate. I also have one cylinder where the exhaust studs are shorter than I would like.
Can any one tell me the part number for the longer studs Lycoming puts in the Prop Governor plate?
I would also like to hear a few opinions on replacing all the exhaust studs with the SS type while I'm here and if doing so is really opening a can of worms better avoided.

Thanks

cln1owner · #2 06-03-2010, 04:50 PM

Lycoming Part# 31C-12-P03
5/16(.3125)-18 - 1 1/2 Inch Stud
(Not sure if the P03 indicates plus .003)

Looks like ECI part number AEL31C12, dartaircraft.com ($1.90)

AEL31C13 - 1 5/8
AEL31C14 - 1 3/4

G-force · #3 06-03-2010, 10:16 PM

Jim: we just went through problems with exhaust studs with Axels 320. If the factory studs are too short, they are probably just threaded in too deep. They do not bottom out or hit a stop, you can thread them in alot farther than you need. One side of the stud is an oversized thread that created an interferance fit into the head, thats all that holds it in there. If the threads in you head are worn, then you will need oversize (a few thousands per oversize step) studs. The oversize end of the stud is even bigger to account for the worn out threads in the head. Perhaps your short ones are just too deep on accident, or loose enough they got threaded in when tighting the nuts.

JonJay · #4 06-04-2010, 08:21 AM

http://www.vansairforce.com/communit...ighlight=studs

I recently changed out a few on my Bucker. I ran a tap through to clean up the threads then it is really, really important to clean out the threads in the head with an appropriate brush. I then blew them out with air. The interference threads on the stud will gall easily if the threads are contaminated.
As long as your within range of minimum and max torque you can have them any length that works for your flanges.

jdeas · #5 06-04-2010, 03:09 PM

Thanks guys,
I'll try to back out the one pair of exhaust studs and order the longer gov studs on Monday.

JD