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Possible ingition issues

Posted: Fri Sep 06, 2019 9:09 pm
by Macalac
I would be grateful for any advice on what I think may be an ignition problem on a 1977 3L Ghia

I have had a problem with starting and running for some time since I had a failure of the after market electronic ignition system. I rectified that by replacing the distributor and ignition system with an accuspark distributor, which seemed to work. It then worked for a while but then I had issues with the carb, where I could not get it to tune at all, and when I adjusted the needle valve on one side it made no difference at all. So having looked at the likely cost of a rebuild and/or getting a garage to have a look I decided to replace the carb with a new one.

That has worked and starting and running is a lot better. Now to the problem I have.

Once warmed up the engine is a bit "lumpy" and before I started to adjust the needle valves I thought I would check the timing with a timing light. I have a basic Drapers clip on type of timing light. When I clipped on to No 1 lead it did not appear to work, but I checked to see if it was working by trying another lead. Works fine on No3, but not on any others.

I then started experimenting and pulled the No1 lead out of the distributor with the light clipped on. Made no difference to the running of the engine, but as I pulled the lead out the light worked, and there was a steady spark between the end of the lead and the distributor cap. Put the lead back in and the light stops working. I have tried this on all the other leads and it is the same. Odd to say the least.

Further experimenting reveals that when I rev the engine a bit the light works on all of the leads all the time, until the revs drop to below around 1000 rpm. Engine smooths out as well when revved.

Any suggestions would be welcome.

Re: Possible ingition issues

Posted: Fri Sep 06, 2019 9:36 pm
by Peter-S
I have found with my timing light that it makes a difference if the part that clips on the plug lead is sitting on the top of the lead rather than hanging below if you follow so might be worth changing the way you have connected it and trying again.

Re: Possible ingition issues

Posted: Sat Sep 07, 2019 6:02 am
by Mc Tool
Have a real close look at your clip on pick up, make sure none of the magnets are cracked, ( they don't like being dropped on the floor ). If they are they don't work as efficiently . Check also that there are no magnet "crumbs" holding the joining surfaces of the clip apart.
When you remove the lead causing a spark to jump some distance.......well the bigger the gap the more voltage required to bridge it . The rise in voltage required to bridge the larger gap is also enough to trigger a dodgy or weak pick up. How old are the plug leads?

Re: Possible ingition issues

Posted: Sat Sep 07, 2019 7:31 am
by Macalac
Thanks for the advice. I will try that later.

Leads are about 2 years old but not done much mileage

Re: Possible ingition issues

Posted: Tue Nov 26, 2019 9:25 pm
by Macalac
Just an update - Eventually got round to ordering new leads and plugs. Problem sorted !

Re: Possible ingition issues

Posted: Wed Nov 27, 2019 2:25 pm
by Not_Anumber
Thats a good result. Glad to hear it was neither complicated nor expensive to put right.