HT leads

[mickParticipant @mick65121]

[mickParticipant @mick65121]

Electronics has never been my strong point, but I'm currently trying to sort out the ignition on my latest I/C engine, all that's really needed now is connecting up the four contacts in the distributor to the plugs and the lead from the coil to the distributor. I bought some cored H/T lead, but at 6mm diameter its a bit big and would look clumsy coming out of the distributor. Does the team think that standard electrical cable is suitable for this application.

Thanks.

[Jeff DaymanParticipant @jeffdayman43397]

Depends on the HT voltage, but usually you will experience arcing to nearby metal and burn through of insulation on IC ignitions using regular PVC insulation wire over about 1200 to 1500 V.

Some test meter leads are silicone insulated and are good to 15000 V. Check with an electronics supply firm. These leads are about 3 mm dia. They are not inexpensive though. The electronics supply place may be able to recommend an alternate high voltage wire also.

I did once use silicone fuel line over a regular PVC insulated wire on an RC aircraft engine HT lead and it worked OK at least for the day I messed around with that engine for a friend.

If there is no grounded metal within 10 or so mm of the wire and the wire can be stretched taut, a bare wire may work also.

JD

[JasonBModerator @jasonb]

It can be had in smaller diameters, this sounds like the silicon insulated stuff Jeff mentions, have a look on S&S's site

I have some that is about 1/8" dia that came from another American ignition supplier.

Green Sparkplug do a 5mm HT wire if thats thin enough

 

J

Edited By JasonB on 30/04/2013 17:27:56

[Clive FarrarParticipant @clivefarrar90441]

High voltage and current Silicone wire can be had from 90 % of RC model shops.

4mm O/D approx 2 mm core and 30+ strands £3.50 / mt

Suggestions

Overlander, BRC hobbies, Giant Shark, Puffin models, Als hobbies, Inwoods, Slough models ,

RC model world, Steve Webb etc

Regards Clive

[steamdaveParticipant @steamdave]

What has also been used is electrical test meter leads.

Dave
The Emerald Isle

[Ian S CParticipant @iansc]

The HT wire from an old CRT TV set should be OK, or the wire for a piezo igniter for a gas stove. Also Teflon insulated HT wire used in valved radio transmitters, these wires are about 3 mm over all diameter. Ian S C

[Ady1Participant @ady1]

Decent HT leads can make a huge difference, even if they look silly

An amazing amount of leakage can occur from weedy or old HT leads

 

The difference can add up to a healthly engine note with no misfires, especially on older engines

I was amazed at the difference decent leads made to my clunky mk2 escort over 30 years ago

Edited By Ady1 on 01/05/2013 15:24:58

[Sub MandrelParticipant @submandrel]

I was amazed at the difference decent leads made to my clunky mk2 escort over 30 years ago

Even with modern ignition systems I have found it necessary to replace HT leads more than once on modern cars.

Neil

[Donhe7Participant @donhe7]

Posted by Graham Meek on 01/05/2013 21:20:02:

The problem with the modern suppressed ignition leads, (pre-engine management days and a coil per plug) was that they had a graphite type yarn core, with the flexing due to vibration from the engine and the extremes of temperature, these items would break down.

It was one of those Automobile manufacturers cost saving ideas that usually cost the mostorist more, in the days of the real Mini these new fangled leads were replaced with good old copper leads and suppression plug caps, fitted once they could be forgot about as long as the outside was kept dry and clean.

Gray,

Regarding the "Mini", here in Oz, it seemed that you only had to hold a PICTURE of a puddle of water in front of them and they would stop!!

donhe7

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

On spark ignition aircraft piston engines the plug leads sometimes have enough reactive properties to affect the spark quality . On radials in particular the leads were relatively long and had grounded metal sheaths .

There were several instances where ' tuning ' the leads made a significant difference to performance and reliability of engines .

Some surprisingly high frequencies are generated in the ignition system of a multi cylinder engine running at several thousand rpm . Apart from the primary spark generating frequency there are many harmonics .

The quality of the harmonics is sometimes credited with making the spark ' good ' or ' not so good ' . Far from an exact science but the way the air / fuel mixture breaks down during ignition and the fact that the spark is to some extent sustained by the harmonics do suggest that there is some truth in this .

Michael Williams .

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