hi, i have mounted a 1.60 fx onto a great planes christen eagle II 29% arf, but the pitts muffler i have bought, is 1 inch short of poking out of the bottom of the cowl, any suggestions on how to fix this problem, is there extensions for the muffler you can buy?

You can go two ways on this problem. You can buy the flexible exhaust extensions that slip on over the muffler stacks and clamp down with a zip tie, or you can purchase some metal tubing that will fit into the opening of the exhaust stacks, cut it to the length you want, and use either solder or JB WELD to attach them. Mind if I ask which PItts muffler you are using? I am running the OS 1.60FX on my Goldberg Pitts 12 with a Brison Pitts muffler, and the stacks stick out of the cowling a good inch. Another bit of info for you... a bunch of people say that the OS 1.60FX wont run well with a Pitts muffler unless you crimp one of the stacks closed, because the muffler wont develop enough back pressure. I would suggest running your engine first and see how it does. I lost count of how many guys told me mine would never run right with both stacks of my Brison muffler open, but it has run like a charm since the first day I installed it, with no back pressure problems.

yeh its a brisson pitts muffler, i was thinking of putting the flexible extensions on, but i was trying to aviod it, even though it looks like im going to have to, because i dont really wanna weld/solder any of it

Just get the large diameter silicone/teflon extensions that are actually used for couplers for between a header and a tuned pipe. They will slide on and never come off unlike the extensions you zip tie on and they are clear and harder to see if that matters.

Something similar to this is what I used. My hobby shop had several diameters in 6" lengths for like $4.00 - put them on and cut them to the right length etc...

http://www2.towerhobbies.com/cgi-bin...?&I=LXJF43&P=0

i just found some small car heater pipe, yes its black but it does the trick, put 2 of them on with hose clamps and bob's ya uncle lol.

I too never had a problem without plugging either.

I have this setup also and it runs strong. No pump or plugging needed.