Any experts on carb heat out there?
I recently got my '65 C model back from annual. During a recent run up check, I applied full carb heat and it resulted in the engine cutting off. I immediately turned carb heat off and the engine recovered normally.
I opened up the cowling and inspected all the ducting to the heat exchanger and to the carb air inlet. All clear.
I checked the position of the carb heat flapper door in the air inlet (pic attached) and it closes all the way with carb heat applied. Feels like the mechanic may have greased that cable and now I seem to get a little more throw. As such, the door closes pretty tight.
My question is, is the flapper door suppose to remain open a little even with carb heat fully on? The engine will only cut out as I apply the last quarter inch or so of carb heat.
IMG00933-20131020-1039.jpg 155.92KB 17 downloads
Ok, thanks for all the good ideas. But here's a couple more pics and observations. But previously my carb heat check during engine run up was always a 50-75 RPM drop, I have no carb temp gauge.
the second butterfly valve mentioned several times is connected to the small screen at the nose below the prop. Isn't this an alternate air intake incase the air filter becomes blocked??
The other pic shows the carb heat cable fully retracted (carb heat on and flapper door in the full down position) and the second butterfly valve is closed too. Looks like when the flapper door is closed, it allows heated air from the heat exchanger to enter the air intake from behind the closed door. To me, it only looks like the second butterfly valve is for alternate air (scat tube shown disconnected and you can see the valve closed with carb heat on).