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I was told that if you trim off part of the ground electrode on your spark plugs so that the new end of it is half way over the center electrode, you will increase performance, HP, and gas milage. This is supposed to be an old racers' trick. The guy who told me about it is a regular at the local criuse nights, he has a '57 Cheby and just bought a '65 Mustang convertible. He swears by this, does it to all his cars, lawn mower, snow blower ect. Well, since I was doing a little routine maintenence on the 'stang tonight, oil change and plug cleaning, ( I have a little valve seal issue, and until I pull the head out over the winter to get new seals and hardened seats, I clean the plugs like every 400 miles anyway) I decided to give it a try. Well, without touching the gas pedal, there was a noticable difference in the way the car moved out of the garage and down the driveway! Even SWMBO noticed it! Now I don't know if this will cause the plugs to burn out faster or what, but this seem to hold some promise! Have I been missing this all these years? Anyone else try this or heard of it before? Or am I gonna be buying new plugs next week? I need input please!
 

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I have not heard of doing that before but sounds like you just increased your gap. If your coil is hot enough, then all thoses benifits should be true but I think it will use up your coil and plugs faster. Also, it seems to me that you will get a lot of misfires at higher RPM. But if you just cruse around town under 3K RPM, it might be a good idea. Let us know how it works out over time and good luck :)
 

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replacing your plugs next week shouldnt bother you... replacing your pistons might though. I think by triming them down you are just creating a hotter spark. Not sure if this would put a strain on ones points or not, or if you even run points... either way, id get some advice from the forum people or other elmers if this will hurt the engine in any way... Racers care about 1/4 miles or 500 miles, not the life of an engine, they rebuild thier engine so often, miner things like plug triming might not bother them, just to keep in mind.
 

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This is a guess, but my background is electronics.
The ground electrode(as in circuit ground, not ground off) has an oxide coating to adding resistance and protect it from disintegrating too fast . That's why it is grey/black. Your filing exposed bare metal, reducing the resistance. The half way part just puts the gap in the right place. You could probably do the same thing by filing the underside of the electrode alone and resetting the gap. I agree that it will cause you to go through plugs faster, but they are cheap.
 

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I've seen the same thing at one of the mustang magazine sites or maybe even one of those all for one mags like car craft and phr. they recomend it for nitrous apps but IIRC it will mess up platunim plugs.
 

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We use to do that in the early 70s but we had high output ignition coils made by Mallory. Did it really do any good? Who knows but it made us feel like we knew some cool secret stuff. We also indexed our spark plugs. For those that never heard of that either follow this link:

http://www.fordmuscle.com/archives/2000/07/indexplugs/index.shtml
 

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Autolite racing plugs are as you described with the cutback electrode . An autolite 45 would be an AR45 or equiv . Not really needed except on very hiperf engines .
 

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Seems like I remember something like that being done on high-end dragracers that are burning nitromethane fuel or something. An application where the plugs were used only once then thrown away.
I find it hard to believe it's at all worth doing on anything normally driven. All the spark plug manufacturers are constantly coming up with U-grooves, split fires, and expensive platinum stuff. If just making the electrodes a bit shorter had some viable benefit, seems like they would have noticed it a long time ago.
 

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This is a guess, but my background is electronics.
The ground electrode(as in circuit ground, not ground off) has an oxide coating to adding resistance and protect it from disintegrating too fast . That's why it is grey/black. Your filing exposed bare metal, reducing the resistance.
Just my two cents, and I'm not trying to be offensive. I am an electrician, a field that is MUCH different from electronics. Electricity naturally follows the path with the least amount of resistance. The spark is caused by the current "leaping" across the gap. If the oxide coating increases resistance, wouldn't it reduce efficiency in a spark plug? Also, whether or not it "protects it from disentigrating too fast", it is the METAL that actually conducts the electricity. If the coating wasn't there, it would still conduct, so exposing bare copper shouldn't harm anything. Above all else, spark plugs are relatively inexpensive, and any added strain to the cylinder would be neglible. It wouldn't affect the life of your engine. Again, this is just my two cents.
 

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Not meaning to offend, but your comment, "replaceing your pistons might [bother you]" is, uh, a little exagerated. Run a hundred-thousand volts through your plugs and the jolt will still not come close to the energy released by the explosion of gas it ignites. A hotter spark doesn't increase power in and of itself. It simply furthers the chance of consistent and complete combustion. Filing the plugs won't hurt your engine. It simply gives your plugs a huge headstart in their inevitable journey of wearing out and needing replacement. Some racers do it so I suppose it might help make more power. Plug manufacturers are obviously more focused on the zillion commuter cars that wont's see a new plug for 30,000 miles or more.
 

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When you file the tip so the ground strap ends directly above the electrod it allows the spark to be more fully exposed to the enter of the chamber where the fuel misture gets ignited more quickly and often more effeciently. Rather than the explosion occuring to the side of the chamber as in most cases. Were talking fine tuning here. OK

In the many years I've been filing the tips on my plugs I've never noticed them to wear any faster yet they do work better in most cases. However, as the plugs wear from use the gap has a tendensy to widen quicker than if it had the longer protruding ground strap. But it takes MANY miles to do it in most cases. However if your ignition system is a GOOD one the wider gap often helps rather than hinder performance on many engines. Just don't over do it. Newer engines and performance plugs today often run 40-45 gap as compared to old flathead Fords of 30-32 with weaker ignition systems of the past.

Certainly the gap on a plug has nothing to do with the ware on pistons, as stated, the hotter spark merely aids in the complete igniting of the fuel. Which is light/small in comparison to the forthcoming explosion with each stroke.

I hope this helped you some.

Your friend,
Doc the moneymanager
http://www.inficad.com/~moneymanager/Shelbyandmeatshow.jpg
 
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