VW aero Engine Help needed with timing!

[Spriteah]

Hi all,

 

I have been trying to help a fellow flyer with a VW engine. I am having trouble getting the baby to start. Looking for ideas or advice.

 

It's a VW aero conversions.

 

Magneto ignition that has been re-timed. It's a Bendix dual mag D4RN 2021. Has been timed to the K mark and E gap at R which I think is 8 deg BTDC. It has an impulse system to delay 20 Deg to assist with starting.

 

When I check timing on the engine I can adjust it to open points at 8 Degrees BTDC. However the motor will not start. I get the occasional fire but just wont turn over.

 

Any ideas? Does the timing sound correct? Any advice from some that have experience with the VW's or Magneto would be greatly appreciated.

 

Jim Tatlock.

 

 

[Yenn]

I have no experience withthat setup, but would suggest that it may be the impulse coupling confusing the issue. It prevents the spark occuring at whatever before TDC and then lets it go at around TDC. Try turning past the TDC position to get the impulse coupling to let go, then turn back to just before you want the firing point and you may be able to find when it fires and adjust the position.

 

 

[DrZoos]

I suggest go to a VW forum and ask. I bet they know in their sleep

 

 

[facthunter]

There is nothing unusual about a VW engine regards timing. If the impulse is operating it will retard it at start and very low rpm, then it goes fixed timing which should be somewhere around 28 degrees before TDC. This is the condition you adjust it at. ie Non impulse with the weights out as the motor runs not as it starts. You may refine that figure (28degrees) but that is what the 0-200 runs at and it is a typical figure for that style of engine. Nev

 

 

[DrZoos]

http://www.vw-resource.com

 

http://www.volkswagenforum.co.uk/forum.php

 

http://forums.aussieveedubbers.com/viewforum.php?fid=59

 

 

[fly_tornado]

no one uses magnetos in cars

 

 

[Riley]

no one uses magnetos in cars

Wish you'd told me that before I replaced the distributer on my 1937 Riley Kestrel with a magneto. Nevertheless, despite my lack of knowledge, it worked very well.

 

 

[fly_tornado]

why for god's sake would you do something like that?

 

 

[corvairkr]

Hi all,I have been trying to help a fellow flyer with a VW engine. I am having trouble getting the baby to start. Looking for ideas or advice.

 

It's a VW aero conversions.

 

Magneto ignition that has been re-timed. It's a Bendix dual mag D4RN 2021. Has been timed to the K mark and E gap at R which I think is 8 deg BTDC. It has an impulse system to delay 20 Deg to assist with starting.

 

When I check timing on the engine I can adjust it to open points at 8 Degrees BTDC. However the motor will not start. I get the occasional fire but just wont turn over.

 

Any ideas? Does the timing sound correct? Any advice from some that have experience with the VW's or Magneto would be greatly appreciated.

 

Jim Tatlock.

If you have know luck Jim try this Yahoo group they may be able to help.

 

http://groups.yahoo.com/neo/groups/aerovee/info

 

Jason

 

 

[cooperplace]

Hi all,I have been trying to help a fellow flyer with a VW engine. I am having trouble getting the baby to start. Looking for ideas or advice.

 

It's a VW aero conversions.

 

Magneto ignition that has been re-timed. It's a Bendix dual mag D4RN 2021. Has been timed to the K mark and E gap at R which I think is 8 deg BTDC. It has an impulse system to delay 20 Deg to assist with starting.

 

When I check timing on the engine I can adjust it to open points at 8 Degrees BTDC. However the motor will not start. I get the occasional fire but just wont turn over.

 

Any ideas? Does the timing sound correct? Any advice from some that have experience with the VW's or Magneto would be greatly appreciated.

 

Jim Tatlock.

Jim, 8 degrees is typical for that sort of engine. I've rebuilt lots with distributors, and played around a lot with timing. I've never worked on one with a magneto, so I know nothing about that impulse system. I doubt that ignition timing is the reason it won't start. I've had many VW engines, 36hp (revolting thing that it was), 1200, 1300, 1500, 1600, that would start easily with timing set way more retarded or advanced than that. They might not have sounded perfect, but they started.

Presumably you can see fat blue sparks? And it's getting fuel? Has the engine been completely pulled down? if so, is the valve timing correct?

 

The old 6v VWs were horrible to start but that was because the starter motor only got 3.6V. Presumably the starter motor on this is 12V?

 

Good luck.

 

 

[facthunter]

Magneto's,...Why knock them? . They are a completely self contained form of reliable HT ignition. Pretty easy to troubleshoot

 

They don't require a battery or alternator or any external wiring (bar the HT leads ) to operate.

 

Jim check it is not timed 180 degrees out . Firing on the dead stroke instead of the compression one.. Nev.

 

 

[Spriteah]

All. Thanks for the advice so far. I have confirmed plugs are correct. 1432. It does not have a starter (hand start). Good visible spark when actuating Magneto. The 28 Deg is interesting. I have been setting to 8 Deg before TDC. Will experiments and try to retard more (which I have already done). I have checked its not 180 out (even reversed it to be sure). I really think that the spark is not in the correct spot. I have sent to Revmaster for some guidance.

 

Jim.

 

 

[facthunter]

If all the advance you ever get is 8 degrees why would you want to retard it further? The impulse action will retard it anyhow when it actuates. The 28 degrees is full advance and is typical. Plenty of engines run more than that. Modern multi valve run less because of better spark location and better flame propagation. Nev

 

 

[Yenn]

Riley

 

I am interested that you have a Riley Kestrel.

 

I had a 1934 model when I lived in England, Beautiful car, both in looks and running. Pass anything bar petrol pumps and the gear box was a beauty. not many could drive that model without crashing the gears. I really regret not bringing it with me, I believe the six cylinder engine was rare in Aus.

 

 

[Methusala]

Make sure that the engine is well primed before attempting to start. Full choke and pull through 8 blades with throttle closed, switches off. Then open throttle a little and flick. should start within 2-3 tries. If it is flooded then open throttle fully and flick (with some one in the cockpit and chocks in place). As fact hunter says, correct adjustment of tappets is vital. Regards, Don

 

 

[spacesailor]

Hi In case of needing a expert magneto guy, I name.

 

Bryan Gray magneto,s of Cookamidgera.

 

02,68661238

 

Repairs and sells them

 

Spacesailor

 

 

[facthunter]

I worked on my first magneto 61 years ago and have been rebuilding them ever since. I don't know if that makes ME an expert, but experience does play a part in these matters. Nev

 

 

[planedriver]

My guess is timing 180deg. out, or thereabouts. While valve clearances are important, if you have fuel and a spark even somewhere close to the proper setting, it should start and run, even if it runs a bit rough till timing is tweeked up properly.

 

When checking for spark without plug inserted in cylinder, make sure you have piece of wire around the body of plug and connect it to a good earth on the engine, otherwise the mag probably won't like it.

 

Spark MUST BE ON COMPRESSION STROKE as already stated, otherwise all you'll get is the occasional pop and fart like you originally described, but it won't run.

 

Should be easy enough to sort out with a timing light.

 

 

[facthunter]

You might as well get the timing right from the outset. If you want to check the plugs are firing in the correct sequence, remove all(4) plugs and have them on the end of each lead with the plug body earthed. You should never fire a maggy without the secondary (High Tension) circuit completed through a small gap (relatively). Put your thumb over a plug hole and pull the prop and when the compression stroke is indicated by the pressure forcing your thumb off the hole the relevant spark should take place. The impulse will ensure that it is a good spark and you will clearly hear it action. A spark produced by an impulse equipped magneto will fire LATE. Just a few degrees before TDC. Magnetos are set (timed) with the impulse deactivated which is the position they RUN in, which should be much more before TDC. I have suggested 28 degrees. Use this unless you have a RELIABLE figure from someone who knows the VW type you have . This happens when the engines revs are high enough to make the flyweight go to a different position where it does not engage the stationary stop. Since you don't set the timing with the engine running you have to arrange for the flyweight to not engage the stop and go to full advance. You need a timing disc set carefully to reference TDC and a fixed pointer.. Aircraft engines (small ones)normally have degrees set on the rear of the prop drive flange. Nev

 

 

[spacesailor]

I hope you let us know what the problem was when its running well.

 

spacesailor