Author Topic: SPARKPLUG EXTENSION AT PLUGWIRE END  (Read 419 times)

Offline Brian Rupnow

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SPARKPLUG EXTENSION AT PLUGWIRE END
« on: September 12, 2021, 11:56:37 PM »
Has anyone ever seen or know of a sparkplug extension that looks like the one in this picture? The plug is a Rimfire .25-32.  I want to nest this plug down between two rocker arms and not have the spark shorting out and snapping to the rocker arms instead of to the end of the sparkplug. The red and yellow parts I show is the extension. The purple is the original rimfire sparkplug. The red part would have to be steel or brass. The yellow part would be something non-conductive that was resilient like rubber so it would "grip" the end of the sparkplug. Strange question, I know, but I have a reason to ask.---Brian

Offline Brian Rupnow

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #1 on: September 13, 2021, 01:17:54 AM »
Back a year or two ago, when I was trying to set up a governor on that twin, I designed and built a set of heads that moved the sparkplugs up to the center of the heads. The heads were great, but the sparkplugs were so short that sparks were jumping over to the rocker arm towers.


Offline Roger B

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #2 on: September 13, 2021, 07:46:06 AM »
I think that the red part in brass or steel would be too heavy.

If you can fnd a silicon rubber tube that will fit snugly on the plug body then build up the ignition wire to a suitable diameter (with heatshrink?) to be held in the same tube and solder a small spring onto the end of the ignition wire to make the contact too the sparkplug.
Best regards

Roger

Offline Zephyrin

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #3 on: September 13, 2021, 09:03:46 AM »

Recessed sparkplug on a small cylinder head leads to arcing on many spots and also requires a special thinner socket spanner...
you may isolate the plug as indicated by RogerB, which should do it, or have a go in making your own special longer plug.

Offline Brian Rupnow

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #4 on: September 13, 2021, 08:22:48 PM »
I find that Corian is rather brittle stuff to work with. Is there any other material that is commonly available but is still machinable and a good insulator? I have made my own sparkplugs in the past with Corian, but wasn't terribly impressed with it.

Offline Jasonb

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #5 on: September 13, 2021, 08:27:33 PM »
I've used glass tube, just cut it to the length you want with a diamond Dremel disc



Offline Brian Rupnow

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #6 on: September 14, 2021, 02:52:10 PM »
Okay---Don`t laugh.--I have a solution. The inner portion will be made from brass. The outer section will be kiln dried oak wood. The brass core will be Loctited into the wooden outer shell. The wooden outer shell will be Loctited to the sparkplug. The sparkplug never gets hot enough to burn the wood. The wood is a good insulator, and the brass passes the current down to the sparkplug. best part of all is that I have the material to do this.

Offline crueby

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #7 on: September 14, 2021, 05:22:31 PM »
Loctite the brass to wood? Never knew it was compatible with wood.

Offline bent

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #8 on: September 14, 2021, 08:19:31 PM »
Hm, we found that loctite green (the wicking grade) and blue (removable grade) are conductive enough to cause stray shorts on printed circuit boards here at work.  Maybe it will carbonize enough to not matter once it's run awhile at high voltage?

Offline Jasonb

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #9 on: September 14, 2021, 08:38:11 PM »
That Glass and metal one I showed above was bonded together with Loctite "Black Max" #380 which has rubber in it.

Offline Brian Rupnow

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #10 on: September 15, 2021, 01:17:50 AM »
Yes, you're right. no Loctite. I'll epoxy it together.

Offline bent

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Re: SPARKPLUG EXTENSION AT PLUGWIRE END
« Reply #11 on: September 15, 2021, 04:08:48 PM »
Sounds right, Brian.  Jason, I'm not familiar enough with Black Max, but assume it's been formulated to be non-conductive?   I've been trying to source a decent retaining compound for assembly of circuit boards, but not successful yet.