Purchased two Evolution 46NT engines a few weeks ago.
Got one mounted (cowled and a pain to take out over and over again).

I've had nothing but problems with one of the engines. Won't idle, transition problems, etc. Not 100% sure what the problem is but I know we have tried every setting within the limiters. Replaced every fuel line, tried 8 or so different glow plugs, and swapped out with a new tank. Still not reliable.

Noticed that when the engine was running that the muffler was rotating like crazy. Disassembled by unscrewing the flat head screw (how about a allen head next time?). JB Welded the long screw and let dry over night. Low and behold, it continues to rotate.

Took the muffler from the yet to be run engine, JB welded the long screw to the end cap and end nut and same problem. Spent fuel runs like crazy at the mid section of the muffler and usually rotates to the point where it will probably fry my covering on the fuse.

Talked to Horizon Support this morning and they say send both engines back and that there are no problems at all with these mufflers. (I must be the crazy one) I am but tried to not let on.

Ended up taking both motors back to my LHS and exchanged them for two OS 46 AXs. Never had a problem with the OS motors.

Is this a bad muffler design or just me? Thought I would like the evos since a friend has one that seems to run extremely well. I did notice he changed his muffler on his also due to the same issue. My LHS also indicated that he had one other fellow in there ordering a new OS muffler for his evo as it was also rotating with no way known to NASA to stop the rotating and losening.

Any thoughts or experiences?

Regards,
Hank