Coils

[Chris Launders]

I'm not happy with my twin plug set up on my norvin, I think I need to modify my atd ( too much retard) so as an experiment I want to run it single plug and standard timing.
So can I just close up the plug gap of one plug on each cylinder for now or will this damage the coils ?
Chris.

 

[greg brillus]

Hi there Chris, sorry not sure what kind of ignition you have but you could probably disconnect the low tension leads off of the coil itself, as this should not do any harm.......Greg.

 

[Chris Launders]

Hi greg, I have a harley ATD with twin points and twin output Dyna coils, I need to use only one output on each for now so I thought shorting one out would be ok whereas leaving one HT lead off might damage the coils.
Chris.

 

[bmetcalf]

What year and model harley ATD?

 

[Chris Launders]

I don't know, just an aftermarket one. I measured the throw at the time but cannot recall what it was but with twin plugs running 25 degrees BTDC I think it is giving me 8-10 ATDC retarded which is surely too much.
Chris.

 

[greg brillus]

Chris it sounds to me like you need to tinker about with the ATD so you end up with 4 to 6 degrees advance in the retarded position and around 20 odd degrees at full advance, this using the twin spark ignition, which should work fine....If you do go back to single plugs, run the advance up to around 34 degrees. An open circuit at the HT lead will damage the coil, so yes shorting the electrodes would be fine, and do no harm. Cheers.....Greg.

 

[Chris Launders]

Thanks Greg, I was pretty sure about shorting the electrodes, I just wanted some assurance. The thing is horrible to ride below 3000rpm ( mk2 cams, 34mm mukini's it won't tickover properly, vibrates and judders badly around 2000-2500 on gentle throttle opening) so I thought I would go to standard ignition settings and see if thats better then look at the carbs. Then perhaps see to the atd over the winter or leave it and fit single output coils if I'm happy with the single plugs.
Chris.

 

[Bill Cannon]

My Egli is twin plugged and I have always run about 30-32 full advance. I have a lot of experience with airhead BMWs with twin plugs and it is well established that a reduction in full advance of 8 degrees is the way to go. So my conclusion is that you advance to at least 30 and this should get your retarded setting in the ball park.
Bill