HT Leads

[djtaylor]

Drew, for what it's worth, when I was running the copper leads, I suffered an intermittent 7 cylinder issue but that was easy to spot when it remained on 7 cylinders when I parked up and lifted the bonnet. The spark was quite happily arcing through the HT insulation and across to the dipstick.

My solution was very simple - turned the dipstick around to increase the gap and twisted the plug connector a bit the other way. I was part expecting this to be the problem again which was the main reason I changed leads recently but it wasn't, that time it was the loose lead in a plug cap into the distributor cap.

I don't know how old the copper cored leads are but it seemed a clear case of insulation dielectric breakdown which is an entirely different problem to that of conducting the spark along the length of the HT cable.

[dasadrew]

Good grief! I'll certainly follow up that line in the engine bay!

[Kithmo]

Hi Chaps
Back in the seventies i didn't have a Stag but did run fords and BMC stuff that seemed to run ok on copper leads and from what i can remember were pretty much bomb proof. do we need these fancy kinds of leads for the Stag.
Not trying to be funny just curious and always willing to learn. Thank's Chris.

IIRC I think copper leads caused more radio interference.

[dasadrew]

IIRC I think copper leads caused more radio interference.

Copper leads are traditionally used with supressor connectors - they're those ones with a metal shield. Common on older German cars like Mercedes etc.

Spark Plug Metal Connectors.JPG

[CJG]

IIRC I think copper leads caused more radio interference.

Thank's for the reply chaps,
forgotten all about ICE suppression remember having to fit one now on my MK1 Capri.
Just thinking about the Stag i can't remember ever switching the radio on, i don't even know if it works quite happy with the tune it has built in.

[new to this]

7mm Silicone with a carbon core. No sign of any visible heat damage.

I made new leads 8mm silicon carbon core leads,how long did you have your old one's

[Phil S]

just read 2 articles both from manufacturer's claiming to be industry standards, 1 claims 6000 ohm per metres resistance.
the other claims 10 ,000 to 12,000 ohm per foot.
so there we have it...now it's as clear as mud

[DJT]

I received my new leads the other day and measured them straight out of the box. 6 of them were approximately 500 ohm per foot, the others (coil, 4 & 5) were considerably more. The high resistance ones in this set coincided with the low resistance ones left from my previous set, so that is what I have fitted. Not had much chance to drive it since.

[DJT]

After fitting the new leads, etc., the car still had a misfire under load. Having tried everything I could think of I finally looked at the plugs today. I was intending to do so, but two Stag owners suggested this last night as well, so.....

I didn't look at these before as the previous set of Champion plugs lasted 25,000 miles without a problem. This set have only done 6,000. I popped down to ECP this morning and bought 8 NGK BP5ES plugs and have fitted these. Misfire now gone............

One thing I noted with the plugs I took out was that the tips were very white, so it seems I may have the carbs running a little lean. On the plus side, all 8 were exactly the same, so the carbs must both be adjusted equally.