how to hand prop cold engine?

Post-War Aeronca Champ airplanes
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boeing
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how to hand prop cold engine?

Post by boeing »

trying to get a feel for what the best technique is to hand prop a cold engine. I seem to be having problems starting my cont 85 when its cold outside. By cold i mean somewhere around the freezing mark 32f or 0c.
I always pre heat first, and the engine is hot to the touch after applying hot air for around 20 to 30 minutes. i think my problem maybe that the engine is warm enough after the pre heat that i dont need any primer at all. I have been giving it 2 or 3 shots and i seem to be flooding it, because after propping my brains out, then going full throttle (mags off) to clear, it starts right up. once the engine has been running it starts first blade every time. i think next i will try to start it with no primer and then proceed from that point. probably easier to add than take away fuel.

so i guess what i am looking for is advice and techniques on hand propping our planes. ( stromberg carb)
pablo
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Post by pablo »

With my 65 HP Cont in my 7AC, with temps about 32F:

Magnetos and throttle closed (fuel valve open!) I pull the prop about 12 blades, or until I hear at least 4 times "goosh" noise in a row. Then I crack the throttle to the 1000-1200 rpm position (penciled previously), switch to both (contact) and pull one or two blades. If it fails to start I go back to magnetos off and throttle closed. Give two shots of primer, while pulling slowly 6 more blades. Go back to throttle cracked open, switch to both, and usually starts at the first or second pull.
If it fail to start I #@$%*&#@ in a very loud voice, and go to the flooded technique of switch off, throttle full open, twelve blades back (clockwise- as seen from the handpropping position). CHUCKS AND BRAKES ON, throttle to half open, magnetos contact: Pull prop, and usually starts at a high RPM.

If it fails, take a break, and let mother nature heat up the environment.Better: move to Oklahoma.

Pablo
MikeB
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Post by MikeB »

I think the way you're describing it, the engine probably already warm enough. You could try (on initial start) mags off, throttle closed, pull prop through four blades in pull gas in, crack throttle, mags on and hand prop (tied down/chocked).

I have the same problem at times with my A65 if I preheat and prime. Seems I always flood it, so I have to go through the 'deflood' procedure (mags off, throttle open, crank backward about 12 blades, etc.) I always talk to myself after I do this (Throttle closed , switch on) so I don't start it up with the throttle open......that could undoubtably be bad :cry: for all concerned.

When the engine is normal cold, say 50 degree or so, I prime about three shots, crank four blades (mags off), turn the switch on and it will start almost every time :D .

Hope this helps.

Mike Berg
"If God had intended man to fly He would have given us more money"
mike newall
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Post by mike newall »

65, with Stromberg, temperature from 25 - 35f.

3 shots of prime, suck in 4 or 6 blades.

Throttle closed, carb heat hot (acts a little like a choke)

Hold a full charge in the primer

Swing - don't touch the throttle, it runs like a bag of spanners and if it falters, carefully squeeze some prime in.

After a minute or two, it should settle down and be fine.

85, with Marvel Schebler (much nicer ! )

3 shots of prime, hold one out.

Suck in 4 or 6 blades.

Crack the throttle, swing - same procedure as before if it falters.
Ron Babos
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starting

Post by Ron Babos »

I use the same method as Mike Newall. Works like a charm.
Ron
Before you believe anything I say, check with two more people. If they agree, I must be right.
MikeB
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Post by MikeB »

If I'm reading his post correctly (boeing) he has already preheated the engine and seems to be flooding it when he uses the primer (the engine is hot to the touch from preheating). One thing I've discovered on these old timers with updraft caburetor is no two start exactly alike, especially when warm. We have three on our field and they all seem to take a little different technique. Dual impulse Slicks helped mine made a big difference in mine, but I still manage to flood it now and then :? .

Spent this morning putting skis on as we have a good 10 inches on the ground and supposed to get another 8-10 (oh boy). The snow is already so deep in front of the hanger that I finally gave up trying to get it out by myself :evil: and taxied it back in.

Mike Berg
"If God had intended man to fly He would have given us more money"
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Mikek
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Re: how to hand prop cold engine?

Post by Mikek »

boeing wrote: i think next i will try to start it with no primer and then proceed from that point. probably easier to add than take away fuel.
Well now is it starting??
Mike Knemeyer

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