HT leads - this must be the easiest job, right?

[Austin Seven]

Hello,

As part of my quest to eradicate a very sporadic misfire on the Griffith, I've just fitted some new ignition components including a new set of Lucas HT leads. I have already removed the plug extenders and I've fitted basalt socks.

I was never very happy with the previous leads (Magnecor blue) as I always found it tricky to know whether I'd properly engaged the plug terminal in the lead connector - some leads would go on with a slight click (felt rather than heard) but others were more mushy. With the socks fitted it was even more difficult to feel the click.

Anyhow, the new Lucas leads are even worse - the rubber boot is a snug fit on the plug ceramic insulator, and it doesn't slide at all easily. Pushing hard with my fingertips, I can get some on satisfactorily, but others I can feel no click, and I can't even tell from the boot position on the plug whether it is fully home or not.

I rejected the idea of using a lubricant on the boots, as that may create a leakage path for the HT.

This should be the easiest job to do, but I spent an hour just trying to satisfy myself these 8 leads are on properly, and I'm still not sure. What do you fellows do?

[Classic Chim]

Probably bad practice but I use a bit of spittal around the rubber of the caps so they slide over the plug better, seems to work for me, once engines ran upto temp it just evaporates.

[Classic Chim]

If you have or suspect a poor connection at the plug which causes misfires look at the plug lead connector by pulling back the cap if needs be, if it’s making poor contact it will often display corrosion from where sparks jumping cause the coating to breakdown, might even be rusty,,, tell tale sign.
Hope that helps. Check your old leads

[bobfather]

I use standard Lucas leads and also have difficulty feeling the click when the cap terminates. I'm about to fit new Lucas leads and recall reading about dielectric silicone grease on here. Apparently it's the perfect solution to tight plug caps

This stuff
https://www.ebay.co.uk/itm/SILICONE-GREASE-MULTI-U...

Edited by bobfather on Saturday 1st June 14:21

[Austin Seven]

Thank you for these suggestions, good point about the spittle evaporating. Yes will check old leads too.

The silicone grease you linked bobfather does state high voltage insulation and high dielectric strength, so perhaps a thin smear on the inside of the boot will be OK.

Cheers!

[blitzracing]

White spirit would be another good lubricant that will evaporate.

[phillpot]

Contralube, good for HT leads and all other exposed connections

[Sardonicus]

If no pro products are at hand Vaseline will do just fine and most households have that stuff available failing that you may have a gay neighbor who maybe able to step-up with some or similar

[Austin Seven]

Well, it seems I was wrong to reject the idea of lubricant after all. Will give it a try.

I haven't checked with the neighbours, I'll just pop round and ask . . . or maybe not.

Cheers!

[Rob_the_Sparky]

Most oils are good insulators (your coil is most likely to be oil filed) but you should be careful as some can react with rubber, silicone is usually a good option but not sure of its temperature resistance.

[phillpot]

Rob_the_Sparky said:

silicone is usually a good option but not sure of its temperature resistance.

230 degees

[Dalamar]

Could a picture be posted please of how people arrange the HT leads? I can never seem to get a good arrangement with the various lengths.

[indigochim]

I've just replaced mine yesterday and found my new ones fit better as the're shorter and less lead to hide. I've also bought some clamps to hold the leads together.