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Tech Tip #3 - Johnson Model A Inner Muffler

Most of the opposed cylinder Johnson Model A motors have the inner mufflers missing or badly deteriorated. You can easily make a replacement that is spot-on for the original with common 2" copper plumbing tubing available at many home repair or plumbing stores.

Here's what you need:

- Tape measure
- Pipe cutter
- Sharpie marker
- Set punch
- Hammer
- 1/4" drill bit
- Dill press
- Misc wood blocking
- 2-inch copper tubing

Here's how to do it!

Illus #1 . 1929 Johnson A-45
Illus #2. A-35/A-45 Parts book - inner muffler on upper left
Illus #3 . Measure distance between muffler ends (this will vary due to distortion of the muffler ends)
Illus #4 . Ring compresser used to draw line on copper tubing
Illus #5 . Pipe cutter makes a nice clean cut
Illus #6 . Parts manual indicated 12 holes evenly spaced (this worked out to every 1/2" on this example)
Illus #7 . Use of a punch to dimple the copper makes it easier to drill. Note wood blocks used as cribbing to hold tubing
Illus #8 . Holes drilled with a 1/4" bit
Illus #9 . Test fit new inner muffler to be sure of a good snug fit.
Illus #10 . Leftover copper pipe can be used to roll out any dents in the outer muffler can
Illus #11 . Install inner muffler with holes facing down Illus #12 . Motor is now ready to run and will be nice & quiet

Please use common sense when working on anything involving gasoline. Practice good shop techniques and work safely and cleanly. Don't forget to visit our DISCLAIMER before you contemplate doing anything presented on this website.

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