Spark plug wire. Do they have to be copper?

Tom Walker

Tom Walker

Senior Member
I have bad mis-fire with my 32 Tudor on standard ignition system, 6 volts.
When I first got the car I changed the old cracked leads, and bought some fancy new ones. Core is like black string in a plastic sleeve. Is this carbon core, and could that be why I have this mis-fire?

Thanks, Tom.
 
The carbon core wires that I have had in the past tended to break down after a period of time. Best thing going today are spiro wound wires. Or if you don't have any issues with static you could go with solid core stainless.
 
The original wires were indeed solid wire-copper or tinned steel. The lower voltage original coils were not designed to be used with the modern carbon wires as they add resistance and as 51 merc pointed out-they deteriorate over time as well-and the new solid core stainless are a good choice. The spiral wound alternative is fine as well-and these are of course meant to reduce static in your radio-sometimes coupled with resistor style spark plugs as well. I used to buy Whittiker spiral style wires for my 49 ford-they were nice quality-until the co was bought out-and production stopped.
 
Thanks guys, after months of hunting for an answer to this problem, I will junk the carbon wires and see what happens. If it works I'll post result here.

Cheers, Tom.
 
Tom, in my experience, a lot of the problems I have had have been HT related. You need the reistance to be low, so solid wires are good, and don't have the plug gaps too wide. Don't use resistor plug caps either.

The carbon string wires are normally a resistance type. I'd try some solid ones.

Mart.
 
Thanks for all that. I have changed the wires for copper, and I still have a mis-fire.:mad:

There are gazillions of posts about misfires on the Fordbarn, the reason being, no doubt, that there are various causes, not just one, and mis-fires are a common problem. You could (someone probably should) make a flow chart to aid diagnosis. I am convinced mine is electrical not fuel related.

So please bear with me while I explain where i am right now...first ignition system (when I bought car in September '12) was divers helmet coil and standard distributor. I fitted new plug leads (carbon:(), plugs, and I stripped, cleaned and lubed the distributor. Car would run fine till hot then die and would nt start. So I bought and fitted a remote coil and conversion plate for the distributor top. Ran much better, but still way off perfect, thats where I am now.

Since changing the plug wires, I went on a run down to the Autumn Classic meet at Prescott hill-climb in the Cotswolds. (Another story and possibly a write-up, very good to meet you Mart!). Put some decent miles on. So I discovered more about the "new" mis-fire....it occurs only when the engine has warmed up, and only when I have the lights on. And it gets slowly, progressively, worse. Running down to Prescott I left in the dark, lights on, ran fine till warmed up, then started to mis-fire (and it starts only at higher revs). As the sun came up, I turned the lights off and the mis-fire stopped. This was a Eureka moment, because up till now the car has never run properly, always goes sick after running a while. I assume this is a combination of copper leads and the remote coil.

Oh and I also replaced the dynamo because the original one packed up. This could be charging better, though it looks about the same on the ammeter. I have always run with the third brush cranked up to max amps.

So now it seems to be volts related,because the mis-fire only occurs when the lights are on. Yesterday I took some time off and did some volts checks as follows. All these readings are taken off the battery terminals. Battery having sat for a week, engine off: 6.3 volts. Engine running fast ammeter showing 15 amps: 8.2 volts. Same with lights on 7.2 volts and dropping.

I have been deceived by the ammeter ( and my own ignorance). Not all the juice being used goes through the ammeter....ie the lights! So maybe if the lights are on I am getting a nett loss of charge.

I think I need to go on a long run with the lights on and see what the battery voltage settles at?

What I dont know is what the modern coil needs as a minimum voltage to work properly. (I have by-passed the in-line resistor in the original loom). I will ring the people I bought it off.

Any pointers gratefully received.

Cheers, Tom.
 
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