100 + Flights... guaranteed!

The only gasket material you will use is permatex ULTRA Black (No Gasket) high temp metalized silicone gasket compound (any auto parts store)

Install retainer bolts DRY to finger tight. Do not use any kind of threadlocker and make sure there is NO oil on the threads. (Use brakeclean to clean out the holes prior to assembly and also douse the bolt threads if you think there is dirt / oil, etc.)

Spray muffler and bolt bosses with C02 or other means in which to freeze the parts. As an alternative before application of silicone you can also put the muffler and engine in the freezer for 30 minutes. Once assembly is cold enough, install the muffler and tighten bolts to specs. (bolts don't need to be frozen but it won't hurt if they are)

IMPORTANT : Let engine temp completely stabilize and silicone cure before turning crank or starting engine.

Hint - Buy a can of Chemtronics Freeze-It at any electronics store. We use this stuff to troubleshoot circuit boards and it does the job above very well. Its about $5 a can and will last a long time on the shelf.


Its expansion and contraction, along with vibration that loosen muffler bolts. By freezing the parts, you are contracting the aluminum to its lowest point and then setting the bolts. When the parts heat up and expand, they have no where to go but out - further compressing the metal. When it cools back to ambient, its still under tension from the chilling process.

I have never had a muffler come loose once since doing this on dozens of engines.

Remember also when removing the muffler later you will need to COOL the assembly or you could possible STRIP out the threads.

DP