I always disassemble new engine mufflers for the RTV treatment, before I ever run them. I've lost muffler halfs anyway, and it's never been from a loose bolt. Rather, the thru-bolt in my 46AX muffler would occasionally pop it's head right off (the bolt itself would fail). It wasn't overtightened, and had been on over 2 dozen flights. At that point I leaned the engine a tad more (it being well broken in by then), and the extra heat caused the bolt to stretch and fail. The engine didn't quit, it seems to draw fuel quite well even without pressure, though I avoided throttling up (muffler pressure is more and more important as the throttle opens. Idle has the best fuel draw.

I've taken to drilling a tiny hole in the fin of the p-box style mufflers. Then a piece of tie wire ties the rear half to the front half. Next time the bolt breaks, I won't loose the muffler half. That said, anyone know the hole diameter in the 46ax baffle?

J