The International Cessna 170 Association

My carb heat control slides on fast. Basically nothing holding it in place. It is so bad I have to fly holding it in! The notched or toothed metal part attached to the air box is so worn down, rounded over, so much that it doesn’t hold it in place.

My mechanic wants to just put a McFarland control in place with a center button.
I don’t want to replace my original knob for this.From what I can tell none of the repair kits have this part. They only have the piece on the rod that rotates over the notches.
Any suggestions?

Take a look at Spruce’s A-740 Rachel control. It has a 10-32 threaded shaft the knob is threaded onto. They use Loctite to secure the knob. The Q&A section there says it can be special ordered without a knob. McFarlane has similar bowden cables. Read this thread for how to use your original knob on a new cable. If you don’t want to go to that much trouble, put a kink in the wire as described here.

That’s probably the answer! Thanks!