Carb Intake Cold WX Cover

[N95645]

Anyone have/use a cold wx cover for their air filter? I understand cold dense air screws up the fue-air mixture in the carb (too lean?) and the engine will quit if the thottle isn't delicately advanced from idle. I read about this somewhere, maybe here, but I can't find it on the search feature what is needed. This happened to me Friday on roll out on the runway when I advanced the throttle to back-taxi the plowed runway. Air temps were about 22F. I have experience this hesitation before but this was the first time it quit on me. Fortunately, I seem to be the only soul at our airport who goes out when it is below freezing, so I was the only one inconvienced by having to get out, chock it and start it again. Two shot of primer and she started on the first blade as usual when she is warm.
Thoughts?

[Dick Smith]

Re: Carb Intake Cold WX Cover

You might have your mechanic look this over:

http://www.bowersflybaby.com/tech/Cont_SB_idling_failures.pdf

Dick

[VictorBravo]

Re: Carb Intake Cold WX Cover

when I advanced the throttle to back-taxi the plowed runway.

Thoughts?

Sounds more like a problem with the idle mixture setting (large knurled idle screw on the rear passenger side of the carburetor), not the amount of air into the carburetor. Check with the carburetor operating instructions, but I SEEM to remember that turning the screw counter-clockwise will richen the idle mixture and turning it clockwise (screwing it closed) will lean it out a bit. CHECK first!

My suggestion is to richen it about 1/8 of a turn at a time, no more than that, and GROUND-TEST (airplane CHAINED to something) it for smooth acceleration from idle through full power.

If the idle mixture turns out to NOT be the solution, before you go off covering the intake, PLEASE try using carb heat first, which will slightly richen the mixture as well. That seemed to solve an engine failure on takeoff issue I had, although it was not happening right on throttle advance.

Once you close off part of the air intake, you could easily have a loss of power (best case) or an engine hesitation / failure on takeoff due to rich mixture or reduced airflow when you need it. I cannot speak for anyone else but I've never seen or heard any discussion about covering the carburetor air intake.

Bill

[N95645]

Re: Carb Intake Cold WX Cover

Gents,

Thanks. I recall that I had shut off the carb heat before giving it the throttle and that may have contributed to the issue. I have not had the idle setting tweaked for cold WX either as it is still adjusted for warmer WX. I haven't encountered this with temps above freezing nor when I leave carb heat on. Will pursue the issue with your pointers. Thanks!

Tim