Ignition leads cautionary tale

[FordnMassey]

Hi,

Thought I'd share an experience of mine that occurred while working on my Massey Ferguson 35. When trying to resolve a misfire, I replaced the spark plug leads with a new set as shown on the right of the photo, thinking I was improving the ignition system. At 1 year old, they were arcing thru the rubber ends to anything close by.

Not everything new is better.

I have since bought a set as shown on the left, which have hard plastic spark plug ends and are apparently superior. Time will tell.

 

[rScotty]

The best spark plug wires have three insulation coatings and a stranded copper wire that is soldered to the ends caps. Hotrodders and racers have known that they have to make them right that way for years.

But even those parts are hard to come by. When I went to automotive stores - includng NAPA - last year I found they didn't even carry the parts to make up spark plug wires from scratch.

It's such an easy thing to do, and makes such a large difference in performance.
rScotty

 

[Williy]

The best way to find a miss (bad plug wire)
is at night when its dark easy to see the
sparks fly

willy

 

[FordnMassey]

The best way to find a miss (bad plug wire)
is at night when its dark easy to see the
sparks fly

willy

Yep, that's how I accidentally found they were arcing. Otherwise I would not have considered the leads as possibly bad, given how new they were.

 

[metalbender]

Spray a little water while it's running, darkness helps.
Years ago a buddy bought high perf wires for his 70 Hemi Cuda, same wires as the old 354 Hemi used in 1954. Ceramic ends down the tubes.

 

[FordnMassey]

And in breaking news, here's a photo of the distributor cap. Again, 1 year old. That centre post has snapped away or was destroyed by arcing sparks.
I've installed the old one, which I luckily had put aside.
New may not be better.

 

[Oaktree]

But even those parts are hard to come by. When I went to automotive stores - includng NAPA - last year I found they didn't even carry the parts to make up spark plug wires from scratch.

Coil pack ignition systems have been around now for what, 35 years? Way longer than that since tractors had gasoline engines. Can't imagine there's much demand for the old school plug wires anymore. I'm sure what you're looking for can be special ordered or found online.

 

[Norm W]

Ignition wires for boilers are copper wire and well insulated. Unfortunately, they come on a rather large spool. If you have a friend, or can reach somebody, that does boilers they may be able to get you some. The ends (boots) may still be a problem.

 

[DJ54]

NAPA has Belden 7mm copper core wire with silicone jacket sets complete with ends/boots, you just need to cut to size, put distributor boots & ends on. They show 2 different types, not sure what the difference is. https://www.napaonline.com/en/p/BEL700169?impressionRank=1 They used to carry 4 cyl., and 6 cyl. sets, but just the 6 cyl. sets now.

I bought 2 different rolls of Belden 7mm wire at auctions years ago cheap, both probably 75% full of 100' rolls. Still using off one of the rolls and have made numerous sets, and single wires for antique garden tractors. Used up all of my ends boots 2 years ago, and went to NAPA for both, and different end style boots. Had to order them in from the warehouse, but fortunate enough got them the next day.

They also still carry 100' bulk rolls of the 7mm copper core wire, but pretty pricey now a days. Rock Auto also carry's bulk wire. Being I have 20+ tractors, those bulk rolls I bought years ago have well paid for themselves. If you have just a few tractors that need wires replaced, the above sets would probably be the way to go.

 

[Williy]

Years ago I had a small Dodge pickup
and it was missing really bad took it to
the Dodge garage only had it 6 months
so though that it was under warranty
but no they said the plug wires were not
covered after 1 1/2 hours the mech could
not find the problem the inside of the
distributor was burned up! I replaced the
plug wires solved the problem way too
much resistance on the plug wires and
the juice couldn't exit so burned up the
distributor.

willy

 

[jaxs]

And in breaking news, here's a photo of the distributor cap. Again, 1 year old. That centre post has snapped away or was destroyed by arcing sparks.
I've installed the old one, which I luckily had put aside.
New may not be better.

Add condensers to the new may not be better list. I've had condensers that were bad right out of the box and others that failed within 6 months. A bad condenser is the most difficult ignition problem to diagnose. They are so simple to manufacture people are probably making them in their garage and selling them for pennies.

 

[Fuddyduddy1952]

Add condensers to the new may not be better list. I've had condensers that were bad right out of the box and others that failed within 6 months. A bad condenser is the most difficult ignition problem to diagnose. They are so simple to manufacture people are probably making them in their garage and selling them for pennies.

Well...I have a '58 Nash that I had running great...for a month. Then it wouldn't start, it had a very weak spark. Since I'm retired electronic technician I still have test equipment. The (blankety%&^#) brand new condenser was bad. Looking through my parts I found a bag of new old stock condensers from the 50s. They all checked good...all around 0.47ufd. So yes, a lot in what jaxs is saying, don't overlook condensers and never assume new = good!
So many people repair things, then thinking I just replaced this or that when replacement part is bad.
And no, I'll never switch to electronic ignition, I prefer points for so many reasons.

 

[FordnMassey]

Years ago I had a small Dodge pickup
and it was missing really bad took it to
the Dodge garage only had it 6 months
so though that it was under warranty
but no they said the plug wires were not
covered after 1 1/2 hours the mech could
not find the problem the inside of the
distributor was burned up! I replaced the
plug wires solved the problem way too
much resistance on the plug wires and
the juice couldn't exit so burned up the
distributor.

willy

Hi Willy,

That may be a similar case for me. K can't see any reason that the centre post should disintegrate, aside from poor manufacturing, but the remainder seems to be a quality part. Perhaps my bad leads caused this?

 

[Fuddyduddy1952]

I wonder (center post arc) if there was a gap to the rotor button. You can put some play-doh on button, mount cap, remove cap and see if play-doh is flattened.

 

[FordnMassey]

Hi,
Good point. Arcing across a gap may have been the issue. I'll test the reinstalled old cap and report back.

 

[Oaktree]

I replaced the
plug wires solved the problem way too
much resistance on the plug wires and
the juice couldn't exit so burned up the
distributor.

Wasn't the conductor in a lot of plug wires some sort of carbonized string to make for less ignition noise in the radio? Pretty easy to damage, or get a bad connection on one of the ends.

And no, I'll never switch to electronic ignition, I prefer points for so many reasons.

Curiously, what would be those reasons? I have an antique car, first thing I did when I got it was put in a Pertronix. Never looked back. I don't miss points at all.

 

[Fuddyduddy1952]

People disagree with my (and wifes) thinking but our three reasons for points: first the car, motorcycle, tractor is what it is. If we didn't know how it all works and maintenance, why own it? Second is it much more simple. If electronic ignition or fuel injection quits, start walking. Third if you know what you're doing you can fine tune a carburetor or Kettering ignition for better performance and less money. Simplicity is the key.

 

[m1garand762]

Call up the Brillman company. They have all the old time ignition parts. They are my go to supplier for mag parts and wires. You f anyone has the old early L series gravely they have all the parts for those as well

 

[Williy]

I don't remember what was in the wires but
the resistance was so high voltage going
threw was just enough to get it to run.
On a Ford Mustang I had a cap that would
not let me run over 65 mph the cap wire was
long and rubbing against the shaft wore the
coating off the wire hence no speed!

willy