On my 1/2A scale engine (.061) is silicone a good product to use to seal the muffler where it plugs into the engine exhaust port? Is it heat resistant and easily removable? I have never used silicone so I don't know how it is when it dries. Thank you.

I can't see what you're trying to show in the picture. If you're trying to make a gasket then clean the mating surface real well and use red rtv

I too cannot see what you are pointing to in your photo. However, I have been using Silicone Automotive Adhesive Sealant on all parts of my mufflers, except the bolts were I use blue Loctite, for a good 15 years. As soon as I see any kind of a leak I do it over.

+2, I've used Red (high temp) RTV, but lately on my Gas engines I've been using Permatex Ulta Copper...
http://www.permatex.com/products-2/p...t-maker-detail

the stuff does work well!

The area I am referring to is where the muffler plugs into the engine's exhaust port. This motor has the wire strap to keep it on instead of bolts or screws so it has a habit of shifting away from the engine's port opening leaving a noticeable gap between the two so I need something that will prevent it from shifting and to make sure it remains sealed.

The Norvels do leak from there pretty bad. Silicon is fine. I clean the parts real good with Acetone or laquer thinner first so they stick. You could clean one surface, and leave the other one oily so it is removable. The muffler moves anyway, so I think it will still leak, and it doesn't really matter that much. It will still make a mess and leak.

It looks like an AP wasp engine?
On these there is no real mating surface on the muffler, they didn't copy Norvel well enough there...

I have put JB weld on the muffler to get flat surface that can mate towards the cylinder surface, and that helps a bit. Silicon should work too, you might need to redo it every now and then as the muffler fit is very loose.