proping the j 3 cub!!!!

[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.

[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]

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.