New HT leads caught on fire - any idea on cause?

[rgw2012]

I was just out for the 3rd or 4th 30 min spin after replacing the full set of HT leads with 8.5mm leads from Mr Retro leads - suddenly started misfiring badly so pulled over and then the engine died. My son then noticed smoke from under the bonnet so lifted it up and the king lead was on fire at the dizzy cap and catching the surrounding leads on fire too. A quick blast of the extinguisher sorted it before any real damage was done to other components (aside from the vacuum advance tube having melted in half). Photos below but wondered if anyone could speculate as to possible cause? Is it possible that one of the new HT leads was faulty or could it be the dizzy cap in some way? I am lost as to how it could have happened.

[Steve_D]

I can imagine a faulty lead arching but actually on fire and burning does not make sense.
I think you will be having an interesting conversation with the manufacturer.

Steve

[rgw2012]

Steve_D said:

I can imagine a faulty lead arching but actually on fire and burning does not make sense.
I think you will be having an interesting conversation with the manufacturer.

Steve

Yup, have emailed to seek their views, will report back

[AlexanderV8]

Bloody hell
Couple that with the splitting fuel line problem and you could have had yourself a right old barbecue. Glad you are ok.
No wonder they’re called Retro leads if they become a thing of the past that quickly though.

[Loubaruch]

Have you checked if a fuel hose has failed and sprayed fuel over the leads, that could explain the fire.

[rgw2012]

Loubaruch said:

Have you checked if a fuel hose has failed and sprayed fuel over the leads, that could explain the fire.

Yup, was my immediate thought but no issues noted. I put the old leads back on to replace the damaged ones and it ran home fine

[s p a c e m a n]

That's mad, I've never seen a lead do that before.

[Belle427]

Very strange, normally his stuff is spot on.
Keep us posted on any findings as I do big him up quite a lot and would be interested on the outcome.

[TwinKam]

To my mind there are two separate issues combining here:
1. That something got hot enough to cause ignition...this could be an excessively high resistance eg at a terminal crimp.
2. That the lead material supported combustion...
This I shouldn't have thought possible, certainly nothing I've seen before either, and I can only think a mis-spec of the cable.

[Penelope Stopit]

TwinKam said:

To my mind there are two separate issues combining here:
1. That something got hot enough to cause ignition...this could be an excessively high resistance eg at a terminal crimp.
2. That the lead material supported combustion...
This I shouldn't have thought possible, certainly nothing I've seen before either, and I can only think a mis-spec of the cable.

Me too

[lancelin]

I’ve built a couple of sets of mr retro leads and the materials look top quality. Hard to see how they could catch fire. I have some spare 8.5mm lead so will do some experiments. The outer is obviously silicone but wonder if the inner part is combustible.