HT lead questions

An alchemy of sparks, copper wire and earth

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mattst25
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Joined: 27 Feb 2011, 11:24
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Location: Newport, South Wales

HT lead questions

Post by mattst25 »

Hello everyone, I was wondering if someone could help me with a few questions on HT leads.
While I was making some new leads up today I noticed that the resistance of the plug caps for cylinders 2 and 4 were 5 K ohm and the caps for 1 and 3 were only 1 K ohm. I had assumed that all would be the same, but is this correct?
Also I was going to make a new king lead from the coil to the dizzy cap but when I removed the old one I noticed that the HT lead on this was not 'cut back' exposing the core for the crimp connectors to make contact with. I assume therefore that the crimps are in the cable only to hold it in place and the spark just jumps from the coil to HT lead core and core to dizzy as some kind of spark intensifier? Is this also correct?
I have tried to seach before asking but cannot find a post dealing with plug cap resistance or making leads.
1981 2ltr CU electronic ignition.
The engine was running fine before I made the leads and I was only replacing them as I have done so much on the engine so far they were just the next things tho be replaced. After fitting the new leads (except king) the engine is still running fine and started first key turn. There is no problem, just wondering about the different resistance of the caps and the different construction of the king lead.

California Dreamin
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Location: Nottingham

Re: HT lead questions

Post by California Dreamin »

The resistance is only there for radio supression (to minimize radio interference etc) and serves no other real purpose....yes the caps should all be the same.
And
The carbon inpregnated string (HT core) should have a pin down it's core on the terminal ends and then bent backwards on itself. In it's abscence the spark will just track across but this is not ideal.
20mm of paperclip does the job.
Ends should be crimped with a proper tool.
Old fashioned leads were made with copper and rarely gave any proplems....always pull the leads off by their ends otherwise the lead can be stretched and break down internally.

Martin
1989 California 2.1MV

mattst25
Registered user
Posts: 4
Joined: 27 Feb 2011, 11:24
80-90 Mem No: 9306
Location: Newport, South Wales

Re: HT lead questions

Post by mattst25 »

Thanks Martin, I'll pick up some new caps so they all match and replace the king lead so I know all is as it should be.

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