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  View original topic: What would cause spark plug wires to catch fire?
djsun Fri Oct 01, 2010 1:06 am

What would cause this to happen?



That car had been running and driving for about 15 min in about 60 degree weather when I noticed a loss of power I pulled over, opened the deck lid and the spark plug wires were on fire? I just blew it out like a candle.

The engine was very hot, the after market alternator was super hot, fuel pump was hot so I'm not sure if the wires burnt from the inside out or caught fire from the hot engine.

It has been running great as is for about 3000 miles scene the engine was built.

Its a 1776 w/ 8 to1 compression, and I run super in it. Is has a "Flame thrower/compufirer" Distributer, stock mechanical fuel pump, 40 mm Webbers, over the top exhaust Single muffler exhaust.

I haven't had any time to do any troubleshooting yet. I'm tired and I'm going to bed.

VWporscheGT3 Fri Oct 01, 2010 5:52 am

run some 8mm wires on it. try it again... looks like you were running too much voltage for your wire set

raygreenwood Fri Oct 01, 2010 12:25 pm

VWporscheGT3 wrote: run some 8mm wires on it. try it again... looks like you were running too much voltage for your wire set


Not at all. The Pertronix flamethrower is about 42kv compared to stock with 18kv. Though thats much better....there is virtually nothing on any igniticon system that would burn a copper core wire due to having too much voltage. I have used largely the identical wire on 300kv boiler ignitors.

What causes that is a hole in the insulating silicone of the wire...either worn or cut...that allows arcing to a very close piece of metal that is grounded (thats one possibility).
The most common cause of that is an actually cracked wire core...or even a wire core pulled away from the metal end...but close enough together to arc....or hanging by a couplle of strands.

If the wire is just connected by a few strands of wire...those strands of wire will burn like the filament in a lighbulb...and burn right through the rubber. Ray

djsun Fri Oct 01, 2010 12:34 pm

raygreenwood wrote: VWporscheGT3 wrote: run some 8mm wires on it. try it again... looks like you were running too much voltage for your wire set


Not at all. The Pertronix flamethrower is about 42kv compared to stock with 18kv. Though thats much better....there is virtually nothing on any igniticon system that would burn a copper core wire due to having too much voltage. I have used largely the identical wire on 300kv boiler ignitors.

What causes that is a hole in the insulating silicone of the wire...either worn or cut...that allows arcing to a very close piece of metal that is grounded (thats one possibility).
The most common cause of that is an actually cracked wire core...or even a wire core pulled away from the metal end...but close enough together to arc....or hanging by a couplle of strands.

If the wire is just connected by a few strands of wire...those strands of wire will burn like the filament in a lighbulb...and burn right through the rubber. Ray


Excellent feedback thank you. I'm afraid to Just Replace the wires as there were brand new last summer and of the 50+ dollar heavy duty variety. After reading your possible reason for the burning through I feel much better about swapping out new cables and just watching it closely.

Notch Fri Oct 01, 2010 1:05 pm

Am I missing something here?!?!
Where is your fuel line?
It looks like the fuel line ruptured or something and you were feeding the fire with fuel and the wires were burnt by the fire below them.
that is if the lower line is in fact missing as it appears (to me) in the pic

No matter what happened you were blessed to have been able to put out the fire without greater damage to the car.
Doug

djsun Fri Oct 01, 2010 1:11 pm

Notch wrote: Am I missing something here?!?!
Where is your fuel line?
It looks like the fuel line ruptured or something and you were feeding the fire with fuel and the wires were burnt by the fire below them.
that is if the lower line is in fact missing as it appears (to me) in the pic

No matter what happened you were blessed to have been able to put out the fire without greater damage to the car.
Doug

I "IN" fuel line has been cut and pulled away in the picture because it started leaking. but at the time of the small fire was still attached. I think having the steal braided saved my ass because the dripping plastic from the plug wires dripped right on the gas line!

djsun Fri Oct 01, 2010 1:14 pm

Shit! maybe you're right maybe the fuel was leaking first and it caught the plug wires on fire. I didn't think of that because the fire was so small and only on the wire itself.

Houstonr Fri Oct 01, 2010 2:27 pm

were those wires rubbing on your engine lid? The reason I mention that is because they technically arent the correct shape of wire for the T3 motor (they have straight connectors at the cap, when they should have 90 degree connectors) The correct set keeps the wires tucked down a bit better.

When you replace them try to find some with 90 degree boots. I am running the 14$ bosch ones from amazon.

djsun Fri Oct 01, 2010 2:40 pm

Houstonr wrote: were those wires rubbing on your engine lid? The reason I mention that is because they technically arent the correct shape of wire for the T3 motor (they have straight connectors at the cap, when they should have 90 degree connectors) The correct set keeps the wires tucked down a bit better.

When you replace them try to find some with 90 degree boots. I am running the 14$ bosch ones from amazon.


Good point! They might have been touching the engine lid. I will make sure to get right angle ones.

W1K1 Sat Oct 02, 2010 7:03 am

These guys make nice wire sets with the correct ends

http://www.auroraelectronics.com/products.htm



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