View Full Version : Using a spring to get better cabin heat?

10-30-2017, 05:47 PM
I have 1969 Citabria with dual exhaust and the cabin heat is marginal at best. I herd a person can get a spring heat it up with a torch to anneal it and wrap it around the exhaust between the heat shroud to catch a little more heat from the exhaust. Anybody herd or done this?

10-30-2017, 07:01 PM
On the "free flowing" cross over exhausts on the Murphy's, that have a very short heat shroud, I use "jack chain" (the same stuff you use for tailwheel chains) and wrap it around the exhaust section under the shroud. A cotter pin at each end to secure the chain to the shroud bosses and safety wire between the spiral wrap of chain to keep it tightly in place. Gives more metal surface for the air to pick up heat from on it's way to the cabin. Generally we feed the inlet air into one side, then SCAT hose to the other sides shroud and then into the cabin.

Currently searching for a picture...

10-30-2017, 07:20 PM
Annealed spring used here on a few planes. Wrapped with safety wire and shorter than the heat shroud. Cessna used to put little fingers on their exhaust cans to do the same. Yes it works.

Also put a couple of 2" aluminum duct adapters inside the cowl facing the front for prop blast air to feed the duals. Mo Betta' airflow especially when on the ground or flying slow,


mike mcs repair
10-30-2017, 10:09 PM
I scratch my head on why annealing would matter.... if it loose/vibrates its gonna cut muffler can anyway...

fire up your lathe, and wind your own "spring"

10-30-2017, 10:14 PM
The only thing annealing does is make the installation easier...than fighting spring tension. I've also annealed them and inserted a hose clamp through the spread coils and installed them on the can. A few side by side clamps with the coils only on the clamp tang. Whatever works.