HT Lead Set

richardpope50 · Post by **richardpope50** » Mon Nov 12, 2012 2:08 pm

I need to have made up a custom set of HT leads and there seems a huge selection of leads. All seem to say ‘high performance’ and cores seem to be made of copper, wire, high resistance, carbon, etc. Then there’s 7mm, 8mm, 8.5mm and 10mm. What should I buy?

My original TVR ones were 7mm and have a core that seems to be multiple strands of a black shiny plastic material – not sure of the correct term. Standard LandRover ones, I think.

I do not need ultra high performance, as it is only road use, so I’ve discounted 10mm. All I want is a good set suitable for a MegaSquirt coil pack set up. The bodywork is GRP, I guess it will get quit hot under the bonnet and I do not want to have electrical interference everywhere.

7mm leads are working out at £60 and 10mm leads around £90 – that all seems a lot.

Is this an easy question to answer?

kiwicar · Post by **kiwicar** » Mon Nov 12, 2012 2:16 pm

"Is this an easy question to answer?"

Er no

I have no real idea, I want some non resistive plug leads for strip use and beyond that I do not know what I need so am watching with interest to any logical thought through argument for any size colour and material.
Currently 8mm silicone looks good to me with a spirel wound conductor but beyond that no idea.
Not trying to hijack your thread, I am just genuinly interested in what people say.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Mon Nov 12, 2012 4:55 pm

The type you have are known as carbon string. Rather old hat now - conductive plastic is the modern way, and that looks like a (thick) single strand.

Not convinced 'spiral' has any actual benefits - although I've nothing against it either. Just that I don't know of any major car maker who used it.

I made up my own leads for my EDIS set-up on my SD1. Bought 8mm conductive plastic and used secondhand connectors - my brother had broken a couple of Escorts and sent me the plug leads. Total cost under £20 - and of course they are exactly the right length.

bodger · Post by **bodger** » Mon Nov 12, 2012 5:03 pm

make your own Copper core ones , that what i did ..never had a problem since

these people do everything you need

http://www.vehicle-wiring-products.eu/V ... mepage.php

sidecar · Post by **sidecar** » Mon Nov 12, 2012 5:40 pm

I guess if your setup is stock-ish then there is no need to go OTT with regards to your leads, I found this article interesting but bear in mind a chap from Magnecor wrote it so he does like his leads!

http://www.magnecor.com/magnecor1/truth.htm

I do run Magnecor leads because I run an MSD system and standard carbon leads would fail eventually. (apparently)

DaveEFI · Post by **DaveEFI** » Mon Nov 12, 2012 6:20 pm

bodger wrote:make your own Copper core ones , that what i did ..never had a problem since

these people do everything you need

http://www.vehicle-wiring-products.eu/V ... mepage.php

Non resistive plug leads - unless used with resistive plugs and connectors - will produce lots of electrical interference. Which can effect both your car as well as others TVs etc. And there is no reason to use solid core - it won't give a 'better' spark than resistive core. It may also damage some types of ignition systems.

bodger · Post by **bodger** » Mon Nov 12, 2012 6:33 pm

They are the only ones that last more than a 5 mins with LPG dave , thats why i use them
its what Tinley Tech recomended me to use , they told me that even OEM leads dont last more than a few months on LPG and they are right

as soon as there was any moisture in the air the OEM ones start tracking ...
never had a problem in over 3 years with copper core .. and my radio works just fine too

Quagmire · Post by **Quagmire** » Mon Nov 12, 2012 10:18 pm

I made my own with carbon core 7mm silicon lead from vehicle wiring products. Have been running lpg and edis coil packs for ages no issues at all. Just route your leads neatly and keep them properly separated...

DaveEFI · Post by **DaveEFI** » Mon Nov 12, 2012 11:53 pm

bodger wrote:They are the only ones that last more than a 5 mins with LPG dave , thats why i use them
its what Tinley Tech recomended me to use , they told me that even OEM leads dont last more than a few months on LPG and they are right
as soon as there was any moisture in the air the OEM ones start tracking ...
never had a problem in over 3 years with copper core .. and my radio works just fine too

I'd like to know the theory behind why solid core leads don't track but restive types do - since this is a function of the insulation?

r2d2hp · Post by **r2d2hp** » Tue Nov 13, 2012 8:17 am

This goes some way to explain why std leads would break down - see item 5

http://www.go-lpg.co.uk/Hints.html

bodger · Post by **bodger** » Tue Nov 13, 2012 8:41 am

r2d2hp wrote:This goes some way to explain why std leads would break down - see item 5

http://www.go-lpg.co.uk/Hints.html

Interesting infomation ..bookmaked for future use , Thankyou

richardpope50 · Post by **richardpope50** » Tue Nov 13, 2012 10:13 am

Many thanks for the very interesting views and links.

I got here as I tried to make my own from the original dizzy HT leads and swapping to coil pack connectors. Using 2nd hand connectors soon proved difficult and then I found the connectors did not 'click' to the coil pack pins so have decided to get a professional set made - lesson is that one always needs proper tools.

I should have said that I have switched to restive spark plugs as suggested to me so for my purposes I'm (probably!) going with generally standard 8mm conductive plastic of similar leads. One can always change later, it's just money.

DaveEFI · Post by **DaveEFI** » Tue Nov 13, 2012 10:26 am

r2d2hp wrote:This goes some way to explain why std leads would break down - see item 5

http://www.go-lpg.co.uk/Hints.html

And what it does say is to make sure you use OEM parts.

Carbon string was the standard suppressor cable which does have a (shortish) service life. The later conductive plastic will have a much greater one. Carbon string dates back to the '50s - conductive plastic is a much more recent invention.

DaveEFI · Post by **DaveEFI** » Tue Nov 13, 2012 10:38 am

If re-using EDIS connectors (may also apply to others) 'inject' some red rubber grease between the cable and shroud. A thin long screwdriver dipped in it worked for me. You'll then get the shrouds off easily without damage.

Cut the old cable off flush with the connector then force some needle nosed pliers into the connector and open it up just enough to remove the remains of the cable.
The correct crimping tool would be ideal, but are expensive. I have one made for BNC video connectors which are a common thing so the crimp tool is cheap(ish), and works just fine. Something like this:-

http://cgi.ebay.co.uk/180981528748

bodger · Post by **bodger** » Tue Nov 13, 2012 12:44 pm

DaveEFI wrote:
r2d2hp wrote:This goes some way to explain why std leads would break down - see item 5

http://www.go-lpg.co.uk/Hints.html
And what it does say is to make sure you use OEM parts.

the ones that dont last ...lol

I like the copper core , i just use the existing connectors and tin them and solder the wire straight to them