[ADP]

Afternoon All,

I'm looking at buying an aircraft powered by a VW 1834cc engine with Leburg ignition which has no starter motor. I had a go at hand-propping it to get it started, however I couldn't (safely!) get enough force into the throw to get it past the compression point (for want of the correct term!). What kept happening was that I would position the blade at the 2 o'clock position and swing from there, however when the blade got to the compression point (between 6-7 o'clock) the blade would simply bounce back to around the 5 o'clock position.

I'm not the most confident of hand-proppers however I had no issue getting the C90-powered Cub I used to own a share in started via hand-propping. My prospective co-owner also had a go and he couldn't manage it either. Part of the issue was that the prop blades were quite narrow, so it was difficult to get purchase on it without wrapping fingers around the trailing edge. Another factor that could affect it is that the engine hadn't been run in a while and only had <20 hours since overhaul.

Can anyone with experience hand-propping VW engines provide some insight as to whether they are normally this difficult to start??

TIA,


Adrian

[CloudHound]

Owned VW powered a/c and swung hundreds of them.

I also own a 1972 VW 1300L in Texas Yellow. Funny thing is that it starts easily with minimal fuss at very low revs. You can also bumps start it on the flat with only a slight push.

So what I'm saying is they're not hard to start.

Back to basics. Big fat spark on all plugs? Timing set correctly? Fuel/air mixture correct?

You can undo the bolts and move the prop round to a better swinging position.

Wear gloves.

Good luck!

[nallen]

Short answer: no they are not! I was in a Jodel D9 group with that same engine/ignition combination and it was very easy to start (when cold and hot; it could be a touch temperamental when warm …). Currently swinging a 1200 VW in a Fournier without problems.

Are you sure the Leburg is set up OK? (The system is configured to fire in such a way that the engine doesn't kick back -- so less chance of finger damage.)

[MichaelP]

The Turbs had Lucas magnetos without impulse couplings and had to be swung under handed, i.e. with the right hand through the six o’clock position.
F l i c king the propeller was more apt as the objective was to provide enough ‘impulse’ to activate the magneto.
Why is fl***ing the propeller considered as swearing?

You do need to use the choke.

I would pull it through a few times with the choke out to prime the cylinders, and then flick the propeller.

I swung a VP1 with a pair of impulse magnetos... It back fired on me several times, finally smacking my thumb.
I was stunned.
So I gave it a really good swing Turb style and it started well enough, then I walked away, and kneeled low to the ground as the shock and pain got to me.

You need to make sure any impulse delays the spark enough for the engine to not backfire on you.

Fortunately the VW engine in the Taifun had a starter, and this engine always started very easily and ran smooth.
I’ll find a picture... The Taifun’s VW engine installation:

[rf3flyer]

I have no experience with the 1834cc VW nor Leburg ignition but I have been hand propping my 1400cc VW motor for a quarter of a century.
Assuming the 1834cc motor spins clockwise viewed from in front, which the various o'clock positions you mention suggests it does, then I'd say that the prop needs to be rotated on it's hub by -60°.
For my own machine I stand behind the prop and from that viewpoint it's starting to come up to compression at about 2 o'clock or 1:30 so it's going past compression about 9 o'clock...ish. My hand is travelling across the top of the engine and my head is not tending to go down potentially into the arc of the prop. Even if working from the front that should still apply but working from behind also gives something to hold on to.

As to ease of starting, in my experience, priming is all.
I will prime, ie pull the choke and suck in for 8 to 12 blades, depending on whether the weather is warm or baltic. Then I find it best to walk away for a minute or so before returning to set throttle and ignition.
Mine will then usually fire by the second blade.

[Paul_Sengupta]

Sounds like the prop isn't mounted in the optimum position for hand swinging by a tall-ish chap. Get the prop into the "just before compression" position before just pulling it across the compression. If that's not a comfortable position, take the prop off and re-mount it!

[MichaelP]

Like “Austin of England”, something to be proud of.
British made carburettors.

The Taifun:

[MichaelP]

Read the manual:

https://skycraft.ltd/docs/Leburg/Manual%202020.pdf

I suspect it’s a fuel delivery problem.
Make sure it’s uncontaminated fuel and that it is getting through the carburettor.
Mogas left for a period often has residue that can form a gummy deposit. Check the fuel system, and do a fuel flow test.
Check the filter in the carb if the flow is good.

[David Wood]

What kept happening was that I would position the blade at the 2 o'clock position and swing from there, however when the blade got to the compression point (between 6-7 o'clock) the blade would simply bounce back to around the 5 o'clock position.

I think that @Paul_Sengupta has probably got it right. It sounds as if the prop isn't mounted in the optimal position. Ideally you need to be going through the compression on the down-stroke of the blade, not at the bottom of the stroke.

I wouldn't be overly concerned about your fingers round the trailing edge of the prop if it's just the tips (famous last words) because in my experience, a kick-back is only likely if you are starting with both mags live and isn't likely to harm you so long as you aren't holding onto the thing. I know that the recommendation is to 'hold the blade' by pushing with the flat of the hand on the prop but, to be honest, that's not very easy and leaves you in quite an unstable position leaning into the prop. I'd rather keep my balance.

[nallen]

Just to add: you have checked that the batteries powering the Leburg are up to snuff, haven't you? If the aircraft has been sitting around for a while (the odds of that are good right now!), they might have died.

[Paul_Sengupta]

All of these may be issues, but if you don't get the engine over the compression, you'll never find out if there's anything else wrong!

[Groundlooper]

I’ve had several VW engined aircraft. Some with Lucas non impulse, some with Slicks and impulse and also the brilliant Leburg system. Worst by far was a Turb with Lucas non impulse and a three bladed prop.
Your prop is in the wrong position relative to your swing and going over the compression. Leburgs fire after Top Dead Centre below 400 rpm so the chance of kick back is minimal providing the timing is right.
It obviously needs fiuel but not to much as a flooded VW can be temperamental. so suggest you start with minimal priming/choke then introduce more fuel rather than the other way round
Being nervous of it is tends to make the swing less forceful. With a Leburg it just needs to get over TDC and I have started by simply moving the prop to a point that the ignition fires. Wear a glove as it aids confidence

Also tie the tail so it can’t jump forward, iI’ve seen it happen. I’m assuming it is chocked

That’s my thoughts that for what it’s worth. I still have all my fingers as well

[Flyin'Dutch']

@ADP You've got family and kids. Don't do it.

[rogcal]

I swung a VP1 with a pair of impulse magnetos... It back fired on me several times, finally smacking my thumb.
I was stunned.

I had that happen with the VW1600 in my Luton Minor 40 years or so ago when I was looking for the "sweet spot" in the ignition timing and set the SR4 mags to 28 degrees BTDC (no impulse units) and had a kick back that clobbered my thumb quite badly.

After running it under cold water for about 10 minutes the pain reduced somewhat and I returned to my aircraft only to find a 5 inch split in the trailing edge of my beautiful Wayne Osborne prop.

Thumb just badly bruised and swollen for a few days, so count myself lucky.

Good old Araldite fixed the prop which went on to give years of service without any issues.

Lesson learnt and reset timing to 25 BTDC.

In answer to the OP's question, sounds like either how the prop is positioned in relation to where it reaches TDC when you swing it or possible an issue with the Leburg set up that should be firing just after TDC or both.

[Ian Melville]

Is the prop set for swinging from behind ? Description of position sounds odd to me.