While breaking in my TT .46 engine at about the end of the first tank the muffler rattled loose a little and some greyish, black liquid was seeping out around the muffler/engine connection. I quickly shut the engine down tightend the muffler up and put it away for the time being. Is this normal? My procedure for break in was as follows:

1. Applied a little after run oil in the carb and top of the cylinder before 1st start-up.
2. Adjusted the needle valve to ~ 2 turns out from lightly tighetned in position
3. Primed the engine
4. Applied the Glow plug ignitor to the engine and cranked it over with electric starter
5. Upon start-up opended to WOT and with a tach adjusted needle valve to ~500 rpms rich of the peak rpm

I am using a 10x6 prop as suggested by the manual. I read the manual several times but it does not give much of a detailed break-in procedure other than don't run it lean and a prolonged break-in is not nessecary and what fuel/prop to use.
I don't believe I did any damage because it still has that tight squeeze when cold at TDC associated with tapered bore ABN engines but I want to make sure. Thanks.

No problem. The black stuff is just from the metal to metal contact. Tighten up the muffler, and run it again. Sounds like you're doing everything right. Another tankfull or two and go flying!

Thank you. I thought that might be what it was from but thought I would ask some more experieced flyers before going further. Thanks.

Btw, that black stuff is often the first sign that something is coming loose on your engine. As Minn says, it's metal rubbing on metal.

If you see it in the future around the muffler, backplate, or head, it's a sure sign something is loose. Sometimes you'll see it appear around the engine mounting bolts, usually indicating that your engine is starting to work loose.

Yes to everything that's been said, and I agree with Mike, sounds like you're doing everything right.

Someone's done some research, and actually pays attention to what's been said or read!

Kudos,
Dennis-

Good information to know. Thank you.

Everything I learned about proper break-in procedure was from this message board and I couldn't have done it without it. Thanks.