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Discussion Starter #1 (Edited)
I've always been setting the Sparkplug gap on my car at .035. Since thats what is listed in every book that I've seen, and also because of the TSB. But I noticed the sticker under the hood of mine, and it states to set the gap at .050. So just for the hell of it I changed the plug gap from .035 to .050. I've notice that the idle is better, so is throttle response. Also computer shows that the MPG has jumped by 2 MPG in town,. I haven't had the time to take her out on the highway yet to check highway MPG. I think, because of that sticker, that the car was built before the TSB was issued. My question is, when they issued that TSB, did they also have to re-flash the PCM, so that you could set the plugs at .035 for cold weather starts ? If so, that maybe why my car runs better with the plugs set at .050. If they didn't need to re-flash the PCM, then why is she running better with the gap set .050 ?
 

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I've heard the .050 gap is better for summer, and .035 for winter.
 
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I have the same sticker in my 1994.

I've also got an "Autherized Modification" sticker on the crossbeam above my radiator saying the plug gaps were set at .35. When I pulled the plugs for the first time, the gap was at .45. It ran perfectly.
 

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I believe that the .035 gap is for cold weather starting issues.
 
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Matt86 said:
What's the proper gap for the 3.3's? The plugs I bought were pre-gapped. My MPG is kinda crappy.

3.3l's don't have the cold weather start issue the 3.5l's do.. what ever stock on the sticker is right.. *i don't trust "pre-gapped" plugs.. I always atleast check em with a gap tool.. most of the time they are close..
 

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The wider the gap the more the resistance.with the modern energy supply the wide gaps prove to be more efficient becouse it creates a hotter spark.The old coil and condensers could not handle the amount of current that is produced today without over heating and frying themselves.point gaps were commonly .022 to .028.
cold weather requires more energy to start if it all goes to the starter your ign. suffers.Hope this sheds a little lite.
Jakestune
 

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Nicely said.

Also, there are no such things as pre-gapped plugs. One model plug may fit several different engines, not to mention they can be bumped in shipping.

Always gap new plugs.

Cheers

BJ
 

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The resistance of an open circuit (gap) is infinite. The ability to jump that gap is a function of the voltage across the gap.
 
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Yes, quite correct.
But we're talking about the increase in voltage nessesary to cause and arc from the cathode to the anode.
Bigger the gap, higher the voltage nessasary for the arc, hotter the spark.
A longer arc also means more of the intake charge is exposed to the source of ignition. Better combustion is the result as the flame front is slightly bigger resulting in a better burn in the comb chamber.
Effeciency is also conditional on chamber design and other factors, but that's it in a nutshell.

Cheers

BJ
 

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Discussion Starter #13
Thanks guys for all the replies ! I just went to Vegas , and back today. And the highway MPG has also increased. I'm now getting 29.5 MPG. Not to bad for the 3.5 going 75 MPH, I think. I'm going to keep the Gap at 0.50 since I'm getting such good performance out of the car. I'll see what happens when it start's to get cold again in the winter. But that's down the road. I'm in the upper 90's here right now, and it's suppose to get around 105 here next week ! I wish it would start to get colder ! :fun_06:
 

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wow, gap your plugs at the correct setting and the engine performance improves.

Simply Amazing........
 

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Great White...

I'm not going to hijack this thread, but....

ANODE and CATHODE indicate doping.

Cathode being the element that gives off electrons and Anode being the element that attracts these electrons. These are simply two terminals seperated with a specified air gap.
 

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The TSB is just a possible way for shop technicians to resolve a cold start issue - a one trip resolution. For us DIY people I interpret the TSB as gapping them at 0.050" unless you have winter starting problems, THEN you reduce the gap from 0.050" to resolve the problem. If you do have problems there's no reason not to start at 0.045", then go to 0.040" if 0.045" isn't enough, then reduce it on down to 0.035" if further reduction is required.

My point is that the engine was designed to run at 0.050" - IMO, the TSB just sets a limit on the reduction you can make if needed ...
 

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Discussion Starter #20
95Intrepisize said:
I may be oblivious, but where does it state the cars were designed to run at .050? All I found was .035, thanks.
Mine stated on the sticker under the hood. I had them set a .035 for the longest time at that gap, just because of everthing that I've read, and also the TSB. But the sticker from the factory shows .050. And since I've set them at that, I'am getting better proformance from her.
 
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