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Spark plug gap question

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old

11-09-2006 18:10:14




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Well the other day a guy asked about plugs not fireing till he pulled the plug wire and held it about 1/8 from the plug. Well now heres my question. If I have an engine that fouls plug if I opened up the gap from say the .025 that it should be to say .035-.040 would the plug be less likely to foul and sort of work like holding the plug wire an 1/8 from the plug?? It got me to thinking that it should help keep them from fouling but figured maybe some one would know for sure?
Thanks
Just sort of a crazy idea maybe?

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Glen in TX

11-10-2006 10:37:33




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
Could help if you have enough juice to fire the wider gap but can still foul like before eventually if carb or engine problems. Like others said they did make those gap add on towers or have them built into some wire ends. Champion did make some auxillary gap plugs for example the UD16 is called auxillary gap plug with gap built in it vs. the standard D16 plug they made. Champion catalogs just recommended those plugs really for hard constant PTO use on a tractor or a generator engine and not really to solve fouling problems. For fouling problems a temporary fix is just running a hotter plug with longer reach until engine problems are fixed.

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Aaron Ford

11-10-2006 09:24:14




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
This answers several questions I have had over the years...

First, a guy comes up with a device at Fords at Carlisle that mounted ijn between the distributors coil tower and the coil wire. It actually made cars run better, no matter which car it was put on....

Second, I have a daily acceleration run in my parts getter. I replace the plugs regularly. I tuned 'er up after 120K of the same cap, wires, and rotor and dropped several (65-57) mph although the truck pulls better everywhere else across the board... This explains it. Hotter spark. Gonna call my dad and try to explain it to him. Thanks guys, Aaron

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RAW in IA

11-10-2006 04:59:42




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
I drovea dump truck once that would foul one or two plugs all the time (used oil). We had put on a set of wire plug wires, but when we changed them to the resistor type wires it quit fouling the plugs. I was taught in autoschool that the resistor type wires give you a hotter spark because it has to build up a higher voltage to get through. The voltage only builds enough to overcome the resistance in the system, being the wires and spark gap.

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RAB

11-09-2006 23:18:05




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
Wrote this on one of those threads: Just don"t do it on a magneto system as they were not designed for that and you may cause the mag windings to fail.
RAB



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MarkB_MI

11-09-2006 19:33:01




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
JC Whitney used to sell a set of spark plug boosters that were nothing but insulated spark gaps that you installed between the plugs and the plug wires. The additional gap raised the spark voltage, which was supposed to keep the plug from fouling out. Of course, when you increase the spark voltage beyond what the ignition system is designed to handle, you're going to have problems with arcing plug wires, etc.

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Jon Hagen

11-09-2006 18:57:59




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
Opening the gap likely would not help much,as the extra gap needs to be before the carbon fouling on the center plug insulator,which is what bleeds off coil voltage before it can get high enough to jump the plug gap. There are two plug makers that have some plugs with an extra spark gap built into the center electrode (NGK and Champion ??). You can tell them by looking at the top plug terminal,the auxillary gap plugs have a tiny vent hole in the top terminal to vent ozone from the extra internal spark gap.
Also there is the 'Aldor" spark plug that has a thermostatic device built into the center electrode that opens a wide auxillary spark gap when the plug is cold,which automatically closes as the plug warms up.

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Jon hagen

11-09-2006 19:10:14




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 Re: Spark plug gap question in reply to Jon Hagen, 11-09-2006 18:57:59  
A quick google check shows tha the plugs with the built in extra spark gap are the NGK "booster gap" and champion "auxiliary gap" plugs.



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coflyboy

11-09-2006 18:49:11




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
You asked for someone who knows for sure and I surely don't but here goes anyhow.
I believe that the ONLY way (other than to fix the underlying problem)to keep plugs from fouling is to get the insulator hotter(hotter plugs). I sure tried with a lot of sick engines.
I've had spark act as you described also. I credited that to, under certain conditions but definitely not normally, a hot spark will short out on a fouled or defective plug more easily than a weaker spark. Also, with the wire held away from the plug timing could be delayed a little. hth

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Deere 40

11-09-2006 18:29:44




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
I think I read somewere that making the wire jump spark makes a hoter spark at the plug. We had a modile B ac that fixed was that way ran good.You could set gap wide or use new plug it wouldn"t run with spark jump in wire. I in joy reading every body"s post on this forum. Deere 40



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B-maniac

11-09-2006 18:28:55




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 Re: Spark plug gap question in reply to old, 11-09-2006 18:10:14  
My opinion is yes it would up to the point where it reaches the limit of the coils power to easily jump the gap under compression pressure. To find that, I guess some experimentation would be in order. Also would make any aged or cracked ignition parts show up, as the spark will take the path of least resistance and that may not be the plug gap!



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jdemaris

11-09-2006 19:22:51




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 Re: Yes in reply to B-maniac, 11-09-2006 18:28:55  
Absolutely correct. That's why high-energy ignition systems with wide plug gaps need better wires as well as other parts. I just had a situation that created its own high-engergy ignition by accident. Hunting camp near me has a 1978 Chevy Blazer used for carting around deer hunters. It got running bad - I took at look at it for them. I found - in the inside of the distributor cap - just a burn-hole where the spring-loaded conductor-pole is supposed to be. It was supposed to rub against the rotating rotor - and it's conductor piece was also completely burnt off and gone. So - spark was jumping a huge gap to get to the plug wires - at least a 1/2". Truck broke up and ran terrible - but did run and I could drive it. Well - I "fixed it" by installing a new cap and rotor - and then - it would not run at all - except for one cylinder firing out of eight (350 V8). Long story short the plugs were all fouled - but with the burnt-out cap and rotor - voltage got so high they fired. Once I fixed it, it did not. This really threw me for a little while - but I put new plugs in it - and it was then fine. On a similar note - I still have my Honda CL175 motorcycle - ca. 1972. It has a two-cylinder engine - but for one year - Honda used an ignition with a single set of points, and one coil with two secondaries (plug wires). I assume it was designed to always fire both plugs every stroke. Problem is - and has been since new - when cold - only one cylinder will fire - and it can be either one - you never know. So, I pull the plug wife off the one that is not firing, and slowly pull it away - with the engine running. A spark will jump - and get longer as I pull away - and when I get to a certain distance - that cylinder begins to fire - and then both are running. Once it warms up a little, all is fine. The next year of production for the bike, Honda changed over to dual points and dual coils - so I suspect they recognized a problem. And - how far can you go? I just found out with my wife's neglected 1995 Subaru Impreza. Just hit 135,000 miles and it's never had spark plugs. It has no distributor or cap - and since it's always ran great - never got plugs. A few mornings ago - it wouldn't start - but "almost" did when I let off the key. First reaction - I got mad at the car. Then I remembered - it's had oil changes and timing belts - but never spark plugs. I pulled them out - the gap was so wide - my plug gapper could not measure - but around a 1/4". Must be the breaking-point where the voltage cannot jump the gap. Other than that, the plugs looked like new. I closed the gaps to .045", and now - all is fine again.

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oldcraneguy

11-10-2006 10:52:11




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 Re: Yes in reply to jdemaris, 11-09-2006 19:22:51  
Heck JD, At least you still had electrodes... I ran a 73 f-100 with a 360 V-8 68000 mi.without changin plugs and for the last 6 or 8k it would miss a bit in the morning til it got warm enough to blow it out then run fine, finally it got to where it wouldnt hit on 8 period so I broke down and pulled the plugs, 4 of them looked like an empty pipe! I mean there was nothin in the first 5/8" of the threads and none of them had more than a pinhead where the ground electrode was I was suprised ANY of em were firing... Ive gotten a little better since then about stayin ontop of those things...lol

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