I'm putting in a .15 and its a little tight. Can the fuel return line off the muffler touch the motor? I'm not sure on the melt point.

xray328,
Ideally you don't want the tubing rubbing against the engine, but it's not going to hurt anything if it does. The temperature isn't the problem because the heat from these motors don't even come close to affecting the silicon tubing. If there is anything to worry about it would be rubbing through the tubing, but I wouldn't even worry about that too much either. It's going to take a lot of airtime to rub through, and I mean A LOT of time. More than any of us will fly in a year!!!

What you have in your picture will be just fine. Don't worry about it and have fun flying!!! [8D]

Ken

I agree with Ken, the way you have it shouldn't be a problem. If you are still concerned, you could make the tube a little longer getting it a bit farther from the head. Another thing you might be able to do -- could you run the tube up and out behind the firewall?? Just a thought. Really though, you should be fine the way it is. ENJOY !!! RED

you can also put a tye wrap right where its touching the head. now the tye wrap will be affected by the head and eventually break off but only takes 2 seconds to put a new one on.
have fun

And a lot of times, the tubing will get blown somewhat by the airflow and won't be touching anything much when the model is in the air. Matter of fact, I was just breaking in a new .46AX and noticed the fuel tubing was blown back as far as it could reach. And that was on the ground with no flight speed.

Most of my planes have the tubing touching the engine head and have not had any problems with the tubing melting. It might be different if it was pressed against the head.[8D]

I have had tubing rub and a hole eventually wear through, but it took years.

The only place it might matter is if it is against the exhaust of a 4 stroke. These do get hot enough near the head to melt silicone tubing.

In your application you will have no problem whatsoever.

Dennis