Author Topic: Help with Dragonfly points (photo)  (Read 1583 times)

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Offline Sgtbiro

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Help with Dragonfly points (photo)
« on: 07 Apr 2020 at 19:48 »
Hi i was wondering if some kind sole out there would be good enough to post some pictures of a Dragonfly distributor and points in a conventional set up as i am having trouble getting a spark, i just want to eliminate the wiring on the distributor as it was in bits when i got it and i am not sure i have got the wiring right.

Cheers Kevin...

Offline EW-Ron

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Re: Help with Dragonfly points (photo)
« Reply #1 on: 08 Apr 2020 at 03:22 »
You are having fun with the wiring !

I can't really help with the distributor side of it, (mine would be different (?)not a duggie) but the distributor
basically functions merely as an off-on-off switch. So it should be simple enough to test if it is doing its job.

As it is now, if you have the power switched on and take the wire that goes to the distributor and earth it,
this should provide power to energize the coil(s). When you detach that wire from the earth, this is the break side
of the make-and-break, and you should get a nice fat blue spark at the spark plug.
(the plug needs to be sitting on the cylinder or some part of the engine that can be earth.)
If not, then the problem is outside the distributor.

A way to test the distributor itself is to take a wire from your battery, have a suitable light bulb in the circuit,
and connect it to the distributer.  Have another wire from the other terminal on the battery to the distributer earth.
When you spin the distributer (best in the correct direction) the bulb should light and go out and light and go out.
If the light is on all the time, or never lights up, then the distributor is not right.

Offline eddie

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Re: Help with Dragonfly points (photo)
« Reply #2 on: 08 Apr 2020 at 10:56 »
As already suggested, insert a bulb in the LT circuit and check that it goes on and off as you open and close the points. If the light stays on contiuously, there is probably a fault in the insulation where the return spring is bolted through the distributor body. If that is OK, remove the bulb and check for a spark at the HT lead from the coil. Again, if that is OK, carefully check out the distributor cap - the actual cap has a top plate that clamps down the 3 HT leads (the centre one from the coil, and the outer 2 to the spark plugs) - between these leads there 2 2BA bolts that retain the top plate. If moisture has been allowed to get into the joint between the cap and top plate, the spark may have shorted between the centre lead and one of the others - via one of the bolts (sparks always take the line of least resistance, and that is to the spark plug that, at the time, is NOT under the compression of the engine). Close scrutiny with a magnifying glass will probably reveal a fine black line - a burn between 2 of the leads - carefully scrape at the line until it is no longer visible, and put a good smear of Vaseline in the joint to prevent further shorting. You should now have a spark at the plugs - if not, your condenser is probably suspect - in use, they can get overheated under the alloy distributor cover - I mount mine on the other end of the lead to the coil, so that it gets a good blast of cooling air. A good replacement condenser is one from a Morris Minor - they don't seem to be voltage sensitive.


Offline Dave

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Re: Help with Dragonfly points (photo)
« Reply #3 on: 09 Apr 2020 at 19:57 »
Thanks to Patrick Whitty for sending the following message and photos. (The server had trouble accepting the photos so we are posting this message on his behalf.)

Quote from: Patrick Whitty
Here are some photographs of my Dragonfly's distributor.
It isn't quite conventional, the coil is the twin spark leaving the rotor arm redundant, but the contact breaker and points are standard.
I recently had a problem getting a spark. I had power from the coil to the nut and bolt assembly passing through the distributor body, but nothing inside the distributor and suspected it was shorting into distributor body.

Having removed the nut and bolt and all the little bits that go with it, I spent ages trying to get it all together again.
There really isn't much room to work in the distributor and that insulating washer kept falling down to the bottom of the bolt so I couldn't slide the contact breaker spring on again.

In the end I glued the washer to the black plastic strip, which is all that prevents the spring from shorting to the body, and that made it much easier. I don't think it was shorting but I didn't get a reliable spark until I had done the nut up really tightly.

Even when I had a spark at both plugs it only ran on one cylinder, until I replaced the spark plugs. It is starting easily now and runs well.

Offline Sgtbiro

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Re: Help with Dragonfly points (photo)
« Reply #4 on: 10 Apr 2020 at 16:54 »
Hi Guys thanks for all your help and advice especially the photos from Patrick, i have now found the reason for all my pain and sleepless nights it was all of my own making, the problem was so simple to fix in the end i had just put the isolating washer on the inside of the distributor on the wrong side of the power in bolt, hence the points were shorting out against the side of the distributor and not getting any power silly me. 

Cheers Kevin.

PS Thank you to Dave at Admin for passing on Patrick's photos.