proping the j 3 cub!!!!

[ACEFLYER2]

hi out there I have been having a problem starting my J 3 cub!!! It took 15- 20 times of swinging the prop through. once it was running it runs great.

[1600vw]

Are you priming the engine before you start swinging the prop. My a-65 starts on the first swing of the prop. I give it three squirts of the primer. Then pump the throttle three times to let the accelerator pump pump three times. I then keep the mags off and pull the prop through three times. Make the mags hot and she fires right up.

Tony

[Bill Greenwood]

My J3

[Bill Greenwood]

My J3 with a C90 starts on the first pull most times from cold, and usually on the 2nd when it has been running and if warm.
Heres my way.

First and above all tie the tail down, and put chocks in front of the wheels. Starting an unsecured plane is nuts. And even with an actual pilot inside, I'd want a tie down andor chocks. Now if you don't have a tie down, chocks are even more important, but a plane can jump chocks if the throttle is open wide.
Next, make sure mags are off, but don't take this for granted, stay out of the prop arc just in case.
Crack the throttle the smallest amount possible, just off closed.
Mine has a primer and I usually use 2 strokes, and remember to let it fill after you pull it out before pushing back in or you don't get the fuel.
2 should be enough. My Stromberg does not have an accelerator pump.
Then maybe try one pull with the mags off to pull fuel into the cylinders.
Then mags on, start close, and as you pull down step back and to the outside.
Carefull, it can kick back and grab a finger.
If it starts it should idle perhaps 600-700 rpm, just trying to move but not quite.
Give it a moment at fast idle and then close the throttle before CAREFULLY removing tail tie down and chocks, with the last chock being in the rt main wheel.
If it won't fire after several pulls, I would experiment with amount of prime. No fire at all probably means no fuel or not enough.
Try a lot of fuel, then pull prop through 2 times mags off and then mags hot and pull.
If you see fuel dripping from carb you are way too rich. In that case you can let it sit a few minutes or turn mags off and turn prop a few times to clear.
Then mags back on to start.
When hot after running I use only one prime or no prime at all.
Seems to me it is more likely to kick back when it is flooded and just cleaning that excess out, so be carefull.

Your carb may not be set right, the idle mixture and speed. Are you using av gas or some substitute? I use 100 ll and it seems to start well.

[L16 Pilot]

Several good ideas posted. I had Champ with an A65. Prime, etc. as Bill indicated. When cold I usually pull the prop through four revs "with the mags off". Then turn the mags on and leave the throttle at idle, generally stand behind the prop and one or two swings will get it going. Seems to me you should hit the compression on about the "two 0 clock' position from the rear or "ten O clock" from the front which indicates the prop is on right. If you do it from the front beware of the giant meat cleaver (prop) and stand away after the swing. Pumping the throttle only works if you have an accelerator pump. If a Stromberg carb, pumping doesn't help. One other thought: starting depends also depends on the magnetos and timing, etc. I happened to have dual impulse Slicks which worked well.

[RetroAcro]

Are you priming the engine before you start swinging the prop. My a-65 starts on the first swing of the prop. I give it three squirts of the primer. Then pump the throttle three times to let the accelerator pump pump three times. I then keep the mags off and pull the prop through three times. Make the mags hot and she fires right up.

Tony

All the A-65's I've ever flown, I never bothered with the primer in warm weather. No accelerator pump on Stromberg carbs as mentioned. In warm weather, throttle closed, three pulls on the prop to suck some fuel in, mags hot and she goes.

[champ driver]

I would love to help you but you don't give us any real information to help you.
What kind of Mags do you have, what carb is on the plane, is the prop indexed correctly and what starting technique are you using, like prime or no prime, do you pull the prop through before or after priming?

[crusty old aviator]

It would have helped, ACEFLYER2, if you'd given us a bit more information, like what you have bolted in between the firewall and the prop. If you're going to hand prop alone, and have long arms, all the safety steps that Bill mentions above are a good idea, but not always available. That's why I set up the engine with priming etc. similar to those above, then when the mags are hot (if you don't have an impulse coupling on at least one mag, forget it), I place my left foot in front of the tire, like a chock, and hold the front wing strut firmly with my left hand, then use my right foot to steady myself and my right hand to swing the prop. If the throttle is a little too advanced, the plane isn't going anywhere with your foot there. If you lose your balance and fall down, you won't end up in the prop, as long as you don't let go of the strut. Dick Wagner taught me this technique when checking me out in his Little Myrt and I've used it ever since.

If you do have one of those nightmare scenarios where your plane gets loose with the throttle open, don't grab a wing strut, jump on the horizontal tail and push or pull the rudder to direct the plane into the side of a hangar, a fence, an SUV, or at least away from people.

[1600vw]

I installed this to my tailwheel airplane.

http://www.bowersflybaby.com/tech/tailhook.html

Tony

[nrpetersen]

I find it works well to first just hand prop and let the engine bounce thru compression with closed-throttle-switch-off-mixture-rich to "juice" up the engine, maybe using a little prime only for a cold engine that has been sitting. I then hand prop my J-4A C-85 again on a completely closed throttle. The advantage of closed throttle is you get a momentary vacuum in the intake manifold which will help flash any liquid into vapor.

I think many try to start with too many shots of prime and too much "throttle crack".

[1600vw]

I find it works well to first just hand prop and let the engine bounce thru compression with closed-throttle-switch-off-mixture-rich to "juice" up the engine, maybe using a little prime only for a cold engine that has been sitting. I then hand prop my J-4A C-85 again on a completely closed throttle. The advantage of closed throttle is you get a momentary vacuum in the intake manifold which will help flash any liquid into vapor.

I think many try to start with too many shots of prime and too much "throttle crack".

Starting my a-65 yesterday I had to crack the throttle. Pulled her through a couple times. She would fire but would not lite. I walked around, pushed the throttle in just a tad, and she fired and ran on the first pull.

Now my a-65 only primes two cylinders. I might change this, but she starts so easy, why go through all the work.

Tony

P.S. My carb has accelerator pump. I also have dual impulse on eisemann mags.

4887

4888

[Bill Greenwood]

Could also depend on the person propping. If the propper has spent the winter on a diet of cheese curds and Pepsi, it may result in improper propping.

Get some good Texas Bar B Que or red snapper from Galveston in you before taking on that snarling C 65 or C 90. It works for me.

[Bob Dingley]

Could also depend on the person propping. If the proper has spent the winter on a diet of cheese curds and Pepsi, it may result in improper propping.
Get some good Texas Bar B Que or red snapper from Galveston in you before taking on that snarling C 65 or C 90. It works for me.
You aint lived until you have hand propped an O-470.

[cub builder]

You aint lived until you have hand propped an O-470.

Hmm. I thought the O-470 was one of the easier engines I've propped. All you have to do is barely drag it through with the throttle closed and it will start and run at extremely low RPMs thanks to being a 6 with one cylinder always firing. No need to rare back and kill yourself trying to spin it like an A-65. I found a cold R-985 on a Stearman to be challenging, mostly because you have to reach so high to get a grip on the prop and pull it through more than one cylinder. And an O-540 with the starter drive hung in the ring gear took a bit of effort to get to start so it would throw the starter drive back out. Then we could taxi it to where we needed the plane to repair the electrical system.

It seems that every engine likes it's own technique and it depends a great deal on the engine configuration and condition of the carb, mags, etc. The original post wasn't specific as to whether the hard starting has been a chronic condition, or something new to the plane, nor did he say what technique he was using. I find that the small Continentals don't like to start hot. I sometimes need to turn the engine backwards (stromberg carb) to clear it as it may have enough fuel vaporized in the system that it's too rich to fire.

I do have one overriding view of hand propping. If the engine won't start at an idle, fix the engine. You'll never have an airplane run away from you at low idle. Never open the throttle when you're going to prop the engine. To date, I've owned 5 non-electric aircraft equipped with A-65, C-85, VW, and O-290. Once you find the technique that makes your engine happy (one for cold starts and one for hot starts), it will work 100% of the time. If it doesn't work, you need to fix the engine. Also, always handle the prop as if it's hot. If you prop planes long enough, you will eventually find one with a broken P-lead, so the dead engine will start while you're attempting to clear it. In 40 years of doing this, I've had 2 inadvertent starts while clearing the engine or pulling in the prime. In both cases, everything was off.

-Cub Builder

[Bob Dingley]

Cub,
A BirdDog isn't bad, but a T-34A is a @&*#!

[cub builder]

I haven't played with a T-34A, but suspect the PS-5 on the T-34A makes it hard to hit the right combination to get it to start. The birddog should have a carb like a C-182, which should make it a pussycat to prop. -CB

[Dana]

I'll only add that every engine, even supposedly identical engines, has a combination (prime, pull through, throttle position, flip fast or flip slow, etc.) that it likes best for starting. It can often be a bit of a learning curve to get it right.

[Eric Brown]

With the 65s and 85s that I've had I did find one technique that always worked, when they wouldn't start right away, particularly if the engine was already hot. Mags OFF, open throttle to full open, prop pull engine backwards about 6 times. CLOSE throttle. Mags on. Should start on first normal pull.

[Jeff Point]

4887

Hard to tell in the photo but is that teflon pipe tape on the flared fitting?

[1600vw]

Hard to tell in the photo but is that teflon pipe tape on the flared fitting?


Yes it was. Its all been removed. I took the pics during the inspection of this airplane.

[blane.c]

hi out there I have been having a problem starting my J 3 cub!!! It took 15- 20 times of swinging the prop through. once it was running it runs great. I had a handle on the boot cowl of my Cub to hang on to, it was nice in the snow and mud and such. I propped my Aeronca one time and it started dragging what it was tied to down the ramp, I caught her pretty fast tho. The A-65 in the Aeronca was the hardest to start of anything I have propped once she was hot. It would flood if you looked at it when it was hot, and then you got to prop your guts out to clear it before it will start. Best thing is when you stop it hot is to have it set just the way you want before you cut the mixture, then do not touch anything but the mags when you go to start it. Cold you have to find a system that works whether it is 1 shot of prime or 4 shots it is always the same, it takes a while to figure it out tho.