What HT leads? 3.5 RV8 in a TVR, Lucas dizzy

Fed_up_Stag-owner · Post by **Fed_up_Stag-owner** » Sat May 31, 2014 5:22 pm

Existing Bosch leads showing signs of age, at least 6 years old.

Many suppliers available in my (skinflint) price range, I've narrowed my choice down to 3:
Bosch (from various ebay suppliers)
Powerspark (from simonbbc)
Prospark (from Eurocarparts)

Any comments, adverse or otherwise would be appreciated!

Car is used on the road.

DaveEFI · Post by **DaveEFI** » Sat May 31, 2014 5:53 pm

Being a bigger skinflint, I don't change plug leads unless faulty. If they have no cracks in the insulation, and the resistance measures good, they're ok.

The resistance will be something like 2000 ohms per foot. (They won't all have failed so you can work out the exact resistance of your type)
So 3 feet would be 6000 ohms, etc. A faulty one will be many times this. Don't forget to measure the king lead too. And look for signs of corrosion where the leads go into the dizzy cap/coil.

If they are modern Bosch types, they likely have a conductive plastic core. This is much longer lived that the old 'carbon string' that Lucas used when the engine was new.

Fed_up_Stag-owner · Post by **Fed_up_Stag-owner** » Thu Jul 10, 2014 4:45 pm

Finally got round to measuring the resistance of the leads, first lead I tested was 16k ohms for a one foot length, some green verdigris on the cap end of the lead, also in the cap (would vaseline prevent this occurring?), can also see what appears to be scorch marks on the king lead (possible arcing?).

Should probably also measure insulation values, but my megger is locked in a container 100 miles away.

New Bosch leads purchased for £7.99 for the set, but also had to buy a one off king lead from Accuspark.