Ignition problem or not ?

Hoping the collective wisdom here can help me solve a problem.

My 3000 litre 100/6 developed an annoying misfire. I went through the basics and identified that the rear most set of points in my Mallory twin point dizzy had developed a huge gap and there was lots of evidence of blackening on the base plate presumably from arcing. I had a spare set of points so changed them out and reset gaps at 22 thou where its always been happy. The other original pair of points are not suffering in the least.
Misfire now better but not perfect.

I'd love to know what the underlying problem is. The condenser is a Dennis Welch Supplied apparently unburstable unit that sits remote from the dizzy. Its not electronic ignition. It is still positive earth, the non ballasted coil is wired positive side to the points, there is no other ballast or resistor wire. I noticed the coil does get very hot.
I think I'm on the right rack with this as the car runs like a watch most of the time and is an eager starter I don't perceive any carburation or other issues but have lost confidence in the ignition performance and reliability.

I'm looking for some experienced guidance regarding Correct wiring, Correct Coils, Use of Ballast or not and perhaps a description of how the Mallory twin point system works with the front set of points leading the rear if that makes sense.

Over to you I hope ....

Mallory ignition products are now owned by Holly. They have a tech support contact through their website. Perhaps you have already done so. I can blather about breaker point ignition systems but not the care and feeding of Mallory products. I can't answer your questions but if you contact them I'll bet there may be a Mallory guy on the payroll who can. It sounds like you should speak with someone who knows Mallory set up well, rather than a Healey person. I suspect there are folks who know both lurking on this website.

Thank you. I'll take a look at that Site and live in hope for one of those guys you mention to chime in.
Andy

I suppose I could pitch in my two cents worth of opinion. As with politics, the things politicians are not willing to speak of because they have no answers, are often if not always what the problem is. Unburstable condenser? Makes me want to say this is likley a bad condenser. Get a cheap one to see if it fixes the problem. They are there to keep your points from arcing, nothing more. Were your point surfaces smooth, pitted, or otherwise not nicely shaped?

Be sure and ask the tech guy about whether the coil needs a ballast resistor. I have a Mallory Unilite set in the Mallory distributor with a Mallory coil AND a Mallory ballast resistor (cannot now remember the number of ohms) which is specified for the setup.

Waiting on a reply from Holley. Good call to try a spare condenser. I'll do that and try a ballast resistor. The point surface on the worn set are quite uniform just black and reduced in thickness the leading set are like new.
I'd like to know if the wiring connections in a positive ground car sound correct and if the hot coil could be an indicator...

Just a suggestion here in the UK is Powerspark International, they offer a complete 25 D6 distributor with points for £40 or with electronic for £70

I have had one fitted to my BJ 8 for a couple of years and about 10,000 miles with absolutely no trouble, at that price it seemed hardly worth bothering to have the original one repaired (it had play in the shaft)
I now keep it in the boot all set up with points and leads as an easy roadside replacement.

Here is the link https://simonbbc.com/lucas-25d6-type-distributor/

David Thorn

haasad said:

I'll do that and try a ballast resistor.

Click to expand...

I was not suggesting that you "try" a ballast resistor but rather simply that you ascertain if one is recommended.

I understand Michael I have one in the garage so nothing to lose. And thank you David. DW suggest a condenser change to and to try a new coil. Apparently the wiring is correct but still feels counter intuitive to me. I may change it to neg earth anyway..
Andy

DavidThorn said:

Just a suggestion here in the UK is Powerspark International, they offer a complete 25 D6 distributor with points for £40 or with electronic for £70

I have had one fitted to my BJ 8 for a couple of years and about 10,000 miles with absolutely no trouble, at that price it seemed hardly worth bothering to have the original one repaired (it had play in the shaft)
I now keep it in the boot all set up with points and leads as an easy roadside replacement.

Here is the link https://simonbbc.com/lucas-25d6-type-distributor/

David Thorn

Click to expand...

Those are terrific prices! Are they exchange prices?

No, these are new prices ,not exchange. Hence I was able to keep my original and worn,but working distributor in the boot (trunk) fully fitted up as a spare.

I have purchased several things from them in the past, carbon plug leads for instance, I didn't realise that apparently you should not use copper leads when running electronic ignition.

Easiest is to give them a call (I realise you are across the pond,) and have a short chat. Whenever I have rung they seem very knowledgeable and helpful.

I have no connection with the company . I am not suggesting (nor are they) that these are UK made items by the way.

https://simonbbc.com/

David Thorn

I use the Powerspark electronic ignition, I’ve used it for 3 years, the price at the time was about £30, less than half the competition price over here, so I have a couple of spares just in case. They are very good to deal with.