Crystal Cranks

My caps were a little worse than that, so I replaced caps, rotors (and coils thanks to the " dutchcrunch coil thread". I have to stop reading rennlist it's costing too much money)
I was finding it hard to hold the revs when pulling away in 1st they would drop off a lot as the clutch kicked in. After replacing the parts there was a big difference the engine felt much better/stronger at slow speeds.

Indycam

"You asked for one example of where carbon could come from."
I did not ask where it could have come from ,
I asked where the "carbon" on the post came from in reality .

This "carbon" on the post is not carbon buildup .
The spark erodes the metal the post is made of .
The spark does not take oil / gas / exhaust fumes / pollen / mildew / bacteria / skin oil / skin cells plastic or anything else and coat a "carbon" buildup on the post via the spark .
That is not what happens in the real world .

springer3

My apoligies. You made it sound like you did not believe there was a source of carbon for carbon tracks. I agree black deposits next to the copper terminals is probably oxide.

Indycam

"You made it sound like you did not believe there was a source of carbon for carbon tracks."
.............................
amr89c4
"contacts have high carbon buildup"
.............................
"high carbon buildup" ?
Where did this carbon come from ?
The spark contains no carbon
and the post is not carbon , so where does the carbon come from ?
...........................
So the "carbon" on the posts is the plastic from the cap ?
..........................

"I agree black deposits next to the copper terminals is probably oxide."
I am not talking about what is next to the "copper terminals".
The claim was made that the "contacts have high carbon buildup".
The high carbon buildup was said to "therefore increased resistance".

crg53

Thanks for all the input. So does any of this i.e. carbon deposits and carbon trails point towards poor performing ignition wires? I have no trouble replacing the caps and rotors now, but would rather wait for my winter maintenance, if the wires need to be replaced. I also asked for what the resistance between the posts should be, poorly formulated question, what I meant to ask was, what should the resistance be between the post from inside the cap to where the spark plug wire goes on the outside?

Indycam

The post from inside the cap to outside the cap is solid metal .
The resistance should be zero .

The plug wires provide a path to ground for the spark ,
any resistance down stream from the cap will induce the spark to find another path to ground .
If the resistance goes up a little , the inducement to find a new path goes up a little .
If the resistance goes way up , the inducement to find a new path goes way up .

crg53

Thanks Indycam, that makes sense to me.

darth

"So does any of this i.e. carbon deposits and carbon trails point towards poor performing ignition wires?" Possibly - moisture/contaminants may have started the process but not likely as both caps are in the same environment and only one cap showed signs of wear. Unless one cap was replaced in the past.

A conventional plug wire has a resistance of 10,000 to 15,000 ohms per foot of length--if it's measurably higher, the wire probably is bad. An absolutely failed wire will have a hairline break somewhere, and the resistance will be infinite.

http://www.ehow.com/how_2296047_test...-wire-car.html

The test above is a preliminary test to detect a broken center conductor. More important is the outer insulation and how much the inside core has degraded due to age/use. The above test with an ohm meter is a static test which puts a one DC volt through the wire. In real conditions the wire is trying to contain and conduct 45,000 AC (pulse) volts. If the wires are original - replace, use breaks down the center conductor, oil, temperature, UV and age wear out the insulation.

crg53

This is maybe a silly question, but is there a way to tell the age of the wires, they look OK, but the rubber where they fit onto the caps, is starting to split at the edges on a few of them.

darth

No Silly questions here, just silly answers "Rules of the universe or laws of physics says" - sorry bout that - night out drinking I like to here myself talk or in this case type!


The fact that they're "starting to split at the edges on a few of them" tells you they're old enough to be replaced. I suspect if you trace these wires with the splits back to the cap conductors they will lead you to one of the two posts with the black trace in between them.

Indycam

http://www.beru.com/english/produkte/kabel.php#copper

http://www.beru.com/download/produkt...spekt_zl_e.pdf

http://www.beru.com/download/produkte/TI05_e.pdf


"A conventional plug wire has a resistance of 10,000 to 15,000 ohms per foot of length"
Unless its copper .