Cold Operations and Misc

[3Dreaming]

Re: Cold Operations and Misc

Carb heat richens the mixture.

Marty, I hope you were joking and just forgot the smiley face.

[waltermrich]

Re: Cold Operations and Misc

I have found that durning cold weather the engine will start a lot easier when it is warmed up of course, but if I havn't warmed it up I give it extra prime with temps between 25-40 degrees F, crack the throttle step back to the cabin and reaching thru the door give it extra prime to keep it running, until it warms up. When the engine has been over enriched from prime and it will not start ( no more than 8 pulls) I shut off the mags and pull the prop backwards about 10 times no more prime will be needed and it will generally start on the first try. Hand propping is defiantly something that requires your full attention, and shouldn't be done with out all safety steps in place.

[c tudor]

Re: Cold Operations and Misc

Thank you Gents for your help.

I think we gave up too soon and turned to beer.

Anyway it was a Cub that wouldn't start, so I suppose it wasn't that important. It wouldn't have gone much faster if it had started.

A Taylorcraft would have better manners.

Regards to all,

Chris.

[crispy critter]

Re: Cold Operations and Misc

If the C85 engine is still running a stromberg carb like the A65's then you will find they are more temperamental to cold weather mixture changes then the 65's. Cold weather will lean your mixture and like someone else said. Lean your idle mixture a 1/4-1/2 turn and that should help. Also don't use as much crack on the throttle(hot or cold I also start at dead idle and never crack it), sometimes carb heat will help because it will richen it a bit however with 85's they do tend to flood easier for some reason so keep that in mind. You should be able to tell if it's flooded because it will be running gas out the overflow on the carb pretty hard every time you start trying to prop it. That's when you make sure the throttle is dead idle, mags off, carb heat off, fuel off, and pull her backwards 8-12 blades, then go fuel on, hot mags and try to start it...don't touch anything else. If it doesn't fire on the first blade or two then you may have other issues such as fouled plugs, or simply just a stubborn engine.
Another thing to check in the winter that most folks don't think about is your primer orings. The tend to harden during cold weather and even thou they might not leak, they can allow it to suck air creating a small intake leak....usually doesn't affect the starting to much but does make it stubborn to keep running once it fires.

[c tudor]

Re: Cold Operations and Misc

Thanks Kevin.

It's my friend's cub. We will go and have a play in the next few days.

Couple of questions:

Do you really mean lean the mixture a 1/4 to half turn, or richen it up?

Secondly on the a65 in my Taylorcraft, with no primer, I prime about 16 blades with throttle hard shut, start either shut or just a fraction when cold. When hot a touch more throttle seems to work well.

The only thing I do different to what you said is if it's flooded I go full throttle, wind back 10 or 12 blades, reset throttle, check throttle set at least twice more! And then go mags on and it goes once the fuel comes back in. Usually about 3rd swing. Am I wrong clearing it out with full throttle?

[crispy critter]

Re: Cold Operations and Misc

Richen the mixture in the winter and lean in the summer.
As for a flooded engine.....In my experience it makes no difference whether the throttle is open or closed when turning it backwards. I think the book says to clear a flooded engine by going full throttle and pulling it thru several blades with the mags and fuel off(not backwards). What it does is push all the excess raw fuel thru the engine and dumps it out of the exhaust. The problem in this comes when you forget to turn the mags off, or you have a hot mag and don't know it....the engine fires at full throttle and usually the witnesses are the only ones left to tell thier version of what happened to you.

However by pulling the prop thru backward you are pulling fuel backward out of the engine and dumping it back into the intake where it will run back down thru the carb Venturi and out thru the airbox. By pulling it backwards you not forcing the excess fuel from the carb and intake on thru the engine and out the exhaust, rather your pulling it back into the intake and carb and back out thru the airbox. Pulling it backward doesn't require you to have the throttle open and won't help anything if it is, just adds extra risk in case of an accidental start.

So to answer your question about hand propping a flooded engine....throttle closed, fuel off, mags off, pull the prop backward 8-12 blades. Then double check throttle closed, fuel on, mags on, and she should fire in the first pull or two.