I'm putting together a "GREAT PLANES-PIPER J-3 CUB" arf .40 size with an os46ax engine. Can anyone suggest the proper muffler to fit this combination as the included muffler will not work. It extends back into the firewall instead of down through the cowl.[:@]

You can get muffler extensions for the OS46AX. They are oval tube extensions that fit between the engine and the muffler to move the muffler farther out. They come with a set of longer muffler mounting screws that are sized to the extension. I have seen at least two different size extensions. I use one on my Four Star. It is a 1/2 inch extension, and is the smaller of the two that I've seen.

Scott

The other option would be to mount the engine at 90 degrees from vertical. ie, if you mount the engine with the cylinder head sticking out to the left (as viewed from the pilot's seat), then the muffler will extend down and might clear the firewall.

Or try 45 degrees.
Dennis-

If the engine is already mounted we need to know what position it is in. If it is 90 degrees like DB said then a pitts style muffler is what you need . Bisson and Slimline are 2 good brands to get.

If the engine is straight up or upside down then you need a muffler for a verticle application. Slimline and J'tech have mufflers for this. If you have not mounted the engine, give DB's suggestions some serious thought. One of them should get you fixed up right. Good luck.

Mark Shuman

Thanks for the reply. The engine is mounted with the top of the head facing right (as seated in cockpit) tried each config. of mounting engine with the same result. Took plane to lhs and checked a pitts type muffler (too short to extend through cowl). The instructions show some type of muffler similar to the look of a c.o.2 cartridge. what kind is this?

A slimline has long outlet tubes. If they do not clear you can add some silicone tubing to make up the difference. You need a pitts style muffler. I believe the plane is set up for a slimline and it should fit. Good luck.

Mark Shuman