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  #1 (permalink)  
Old 05-25-2018, 12:58 PM
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Default #6 plug boot shorts to header

I'll look to attach an image later.

I noticed that my #6 plug wire boot had a hole at the bend, and was shorting to the header.

Replaced all the plug wires.

First drive #6 burned through the boot and was again arcing to the exhaust header.

The only remedy I can think of is to remove the header and dimple that tube.

OEM BDR headers attached to crate 302.

Any assistance would be sincerely appreciated.

Roy
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  #2 (permalink)  
Old 05-25-2018, 01:09 PM
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Do you have room to install some heat insulating sleeves?

https://www.jegs.com/c/Spark-Plug-Wi...10401/10002/-1
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Old 05-25-2018, 02:01 PM
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Like previous poster said- use boot insulators. I had your problem on my GT40. Even if insulator touches the header they still work.
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Old 05-25-2018, 02:16 PM
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^^^^
ohhh, I have the insulator and didn't install.
I figured if it touched the header it just wouldn't work.

Thanks fellas, I'll source a new wire without a gaping arc hole and start again.
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Old 05-25-2018, 03:00 PM
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but it won't stop the arc, right ?

nobody seems to sell single wires
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Old 05-25-2018, 03:07 PM
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If you don't have the plug wire actually on the plug or if the plug is bad it will Arc at the Sh!t connection and burn a hole in the boot.

I'd pull the spark plug. If it can't fire the electricity is trying to find a path.

Since you installed a new set of wires and have the same exact results (burned #6 boot) your most likely running on 7 cylinders.

Autolite is running a rebate on several plug lines right now.
http://www.autolite.com/media/18879/...s-2018-web.pdf

AR3924 would be the race application for your engine (cutback ground strap)

Last edited by spdbrake; 05-25-2018 at 03:14 PM.. Reason: adding info
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Old 05-25-2018, 03:43 PM
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I do think she's running on seven.
The unburnt fuel pops on decel.

Didn't know a lazy plug could do that.

Thanks for letting me know where to look.
I had that plug out and thought it looked normal.

edit: it's running NGK-UR45GP (G-Power) gapped .052

Last edited by Ozzie Goat; 05-25-2018 at 05:46 PM..
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Old 05-25-2018, 03:55 PM
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Electricity follows the path of least resistance.

A plug boot heated enough to insulation failure will allow the spark to short to ground especially with large spark plug gaps.

I had plug boots short to ground with 10mm gaps around the boots.

Gary

Last edited by Gaz64; 06-11-2018 at 04:18 PM..
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Old 06-07-2018, 12:53 PM
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I'm running out of options, and this is dumb.

I'm going to get the Taylor wires and see if they defy physics.

I have replaced all the plugs.
I verified the connection as I installed the new wires.
I used a heat sleeve over the plug wire boot etc

Didn't last ten miles. Arc to the header through the lot.

Only other idea is the dimple the header tube.

Last edited by Ozzie Goat; 06-07-2018 at 12:55 PM..
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Old 06-07-2018, 01:21 PM
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The .052" gap your running (most common is 035-040") could be pushing it to find a better path. I'm guessing you dont have the spark plug holes slathered in anti-seize? It can act as an insulator.

Being in proximity to the header pipe 1/2-1" is not an issue. Laying against it is, as it will melt the wire casing.

The last item still on that plug run is the dist cap. Its a stretch though. Although I have seen MSD caps with 1 spark target installed backwards but that just causes random misfires.
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Old 06-07-2018, 01:38 PM
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Thanks Spd. Tips help me not lose it.

I don't know whether to park it. You are correct my assembly has been dry, will seek the grease, and sacrifice another wire !
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Old 06-07-2018, 01:47 PM
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add to the list of things I don't understand:
can I simply gap to .040 and go on ... ?
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Old 06-07-2018, 01:59 PM
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Yup you can re-gap to .040. I'd spin the dizzy cap 180 and reinstall it. If the issue is the cap it will rear its head on the other bank.

Just a light coat of anti-seize on the plug threads is what I meant. Too much is not gonna help.
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Old 06-07-2018, 03:53 PM
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well, that worked - sort of

made it 40min/20miles before blowing out the wire (double earlier results). .040 gap with dielectric grease with a new wire

next up, Accel shorty plugs for headers. need some space between that boot and a ground.
Path of least resistance now appears to be away from the plug.

Last edited by Ozzie Goat; 06-11-2018 at 03:17 PM..
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Old 06-11-2018, 03:18 PM
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after that, I'm out of moves
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Old 06-11-2018, 03:46 PM
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That's somewhat heartening to hear. Have you flipped the dizzy cap yet?

Can you post a pic of the cable run and plug as installed?
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Old 06-11-2018, 03:56 PM
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Since this is the only cylinder clearance challenged and misbehaving I have not flipped the dizzy cap.

A picture would help. (edit, oh lord I'm sorry; I meant it would help if I provided an image)
Agreed that at some point I should reverse the cap installation.

Last edited by Ozzie Goat; 06-11-2018 at 05:15 PM..
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Old 06-11-2018, 04:07 PM
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Sorry, I meant to take the plug wire s off the cap, spin the cap 180 degrees and reinstall it. Then reattached the plug wires again.

Another question. What type of header bolts are you running and have you check them for tightness? I'm suspecting you may have a blown header gasket. Easy to check at idle with a BBQ gas lighter.
When I bought my BDR, I found 3 header bolts missing on the right bank and 2 missing on the left @ 785 miles on the odometer. I installed ARP Drilled head header bolts and Inconel safety wire.

Last edited by spdbrake; 06-11-2018 at 04:19 PM.. Reason: more info
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Old 06-11-2018, 04:33 PM
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I've never heard of a plug lead having such a short life.

Could be a combination of the gap to the header, and a possibly cylinder head grounds. If in doubt, add some ground straps directly to the heads.

Gary
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Old 06-11-2018, 05:18 PM
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Thanks Gents.

I like the idea of grounding straps for the heads.
I will check the TQ of the header bolts, since they are a star pattern a tool purchase is required.

I assume if the gasket is blowing hot air at that plug, then it blows out the BBQ lighter ??
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