Heat muff question on -M1B

[Davepar]

The plans call for mounting the cabin heat muff for an IO-360-M1B (180hp fwd induction) engine on the #1 cylinder exhaust pipe. The problem with that is the SCAT tube routing is rather convoluted.

I saw a couple of builders put it on the #3 cylinder exhaust and pull air off the back of the baffles. The SCAT routing is nice and short, but the heat muff is a bit cramped on that section of pipe:


The bigger problem is that the muff is right over one of the slip joints in the exhaust. Is that a bad thing? Can exhaust leak out of the joint?

Dave

[jcoloccia]

Couldn't you just have it welded? Don't take this as a suggestion as I know nothing about heat muffs and aircraft exhaust systems at the moment. It's just a question from a relative newbie.

[dan]

Originally Posted by Davepar

The bigger problem is that the muff is right over one of the slip joints in the exhaust. Is that a bad thing? Can exhaust leak out of the joint?

That's where I put mine initially until I got a clue. Putting a heat muff over a slip joint or a ball joint or anything that's not just solid sealed exhaust tube is a BAD IDEA imho.

[fodrv7]

Dave,
I have an M1B and a Vetterman exhaust.
I fitted it to the vertical section of the #1 exhaust.
(I do have a vintage undercarriage. Little wheel at the back, but from the look of your pic it should go on the vertical section of #1.)

The scat routing was a bit of a bugger, but the LAME who I had check the FWF came up with an elegant solution.

I have all the cowls off at the moment so I can send you a pic. including the scat routing tomorrow.
I also fitted a CO Monitor.

Dan has an Angle valve engine and the exhaust is quite different. How do I know. Vans sent me an Angle Valve exhaust in error and were so embarrassed that they sent me another straight away. Yes. I still have the other exhaust!!

Shall send the pics tomorrow.
Pete.

[Bob Brown]

I spoke with Van's, who in turn asked me to contact Vetterman's, who in turn put me in touch with Robbins Wings in Colorado. He makes the heat muffs that Van's sells. I had him make another one for me that was 1" longer and had the fittings clocked 100 degrees apart. That allows the scat coming down from the right front baffle area to nicely flow into the muff, and allows the scat going aft from the muff to be routed in a direct manner. I return from Australia next week, and you email me offline next week, I'll send a pic of the install, or you could plow around in my (most unorganized) website (brownsrv7a.net) and see a picture of it in the engine section. It is certainly a cleaner install for your application than what Van's sells...

[fodrv7]

If I had known I would have asked you to bring one South for me Bob.
Pete.

[Davepar]

Thanks for the confirmation. Once I thought about it more, putting it on the #3 exhaust seemed like a bad idea to me as well. It doesn't seem like the exhaust gasses would creep through the slip joint, but even a tiny chance of a tiny bit of CO in the cabin is too much for my comfort level.

I'm installing a Guardian CO detector as well.

Any pictures of the SCAT routing would be great.

I found a tiny picture of Bob's custom heat muff, but couldn't find a larger version. Here's the thumbnail:


That looks much better than having the inlet and outlet facing the same direction.