Ignition lead recommendation

pcmx5 · Postby **pcmx5** » Tue Sep 28, 2010 1:26 pm

mazdatenfive wrote:My MX is 1993 model, done 165,000 k's and still has original leads and runs fine.
How come I have no issues.

Yes , you may have been very lucky, I have had experience with about 7 cases where the original leads have packed it in at low klms on both NA's and Nb's and in some cases it has caused radio interference as well.

Based on that I would always buy better leads but could understand why you wouldn't if you have had no problems.

Peter.

93_Clubman · Postby **93_Clubman** » Tue Sep 28, 2010 2:59 pm

mazdatenfive wrote:My MX is 1993 model, done 165,000 k's and still has original leads and runs fine.
How come I have no issues.

May be they're a set of orignal leads that haven't done the same kms as your car, unless of course you bought the car new or near new & haven't replaced the leads.

Guran · Postby **Guran** » Tue Sep 28, 2010 3:24 pm

Purfler wrote:I'm interested to know how people decide the leads are stuffed, apart from interference and/or sparking visible in the dark. Rod Grainger's book says the correct resistance is 16KOhm per metre. In 3 decades of doing things to cars I have never measured the resistance of ignition leads (which probably says more about me than anything else), but it does seem to be a sensible idea. I'm so old I remember when the leads were copper cored - they NEVER lost their conductivity. Mind you, if you had a radio in your car (bloody luxury) you had a problem

Exactly how many volts do you need at the plug?

Regards,

Tim

When the old leads on my NA6 died, I checked the resistance before and after fitting new ones. Details in the following thread:
viewtopic.php?f=18&t=39032

To cut it short, 16KOhm per metre is the maximum resistance. Higher than that and you'll have problems with getting a spark. OEM leads are around 7KOhm per metre.

Purfler · Postby **Purfler** » Wed Sep 29, 2010 7:59 pm

When the old leads on my NA6 died, I checked the resistance before and after fitting new ones. Details in the following thread:
viewtopic.php?f=18&t=39032

To cut it short, 16KOhm per metre is the maximum resistance. Higher than that and you'll have problems with getting a spark. OEM leads are around 7KOhm per metre.

Thanks for this. I'll check my leads this weekend. I recently changed the leads on my daughter's Astina, which had done about the same K's as my LE, and it now pulls like the proverbial bull at this time of year.

Regards,

Tim