Author Topic: Exhaust Studs and Nuts  (Read 356 times)

yukonranger

Exhaust Studs and Nuts
« on: October 28, 2018, 07:49:56 PM »
Hello, my, late serial number, H295 has 5/16x24 brass nuts on the exhaust studs.  I have seen Helios with steel nuts on the exhaust studs. What is the correct nut and stud? 

Thanks


jmetzler

Re: Exhaust Studs and Nuts
« Reply #1 on: November 01, 2018, 09:39:05 AM »
The nut called out by Lycoming is an STD37. The Helio parts manuals (military and civilian) call out AN121503. Both STC37 and AN212503 are plain steel nuts. Both will corrode and sometimes bring the stud out with them when removed. I've seen brass used, our preference is the MS21046C5 per minor alteration, which is a stainless steel self locking nut. They don't rust, don't need lock washers and come off nicely. Studs come in all kinds of oversize on the thread going into the cylinder.

yukonranger

Re: Exhaust Studs and Nuts
« Reply #2 on: November 07, 2018, 08:10:31 AM »
Thanks Jim.  I see CRES studs are availible too.  Do you recommend those?

Mike

jmetzler

Re: Exhaust Studs and Nuts
« Reply #3 on: November 07, 2018, 03:10:20 PM »
I'd definitely use corrosion resistant nuts. Jim