I have been searching the forum to find out if the 4 cylinder ztech engines need to have the spark plugs gapped? I read how plugs 1 & 3/ 2 & 4 fire at the simultaneously. I read in a post how someone had their plugs gapped to .5 and the others to .4 Just wondering if that applies to my car, or if the Autolite plugs come pre-gapped. I have a 1997 Contour GL. Thanks in advance.
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Spark Plug Gapping Question
- Thread starter Griffon
- Start date
no plug comes pre-gapped for a specific installation.
gap is 0.050"
gap is 0.050"
Actually they can, I believe they pick the most common application of plug and set them at factory. Of course they can be sloppy as heck and you should ALWAYS check them anyway as you do not know if someone has dropped yours on floor and changed it, or if you have the oddball model that sets totally different from most. I have simply seen too many plugs that were close or almost perfect when I checked them. Many motorcycle plugs seem to be close too. I set at .050" too, spec may call for .052 or .054, but slightly closer spec just lets plug last a little longer before gap too wide. .040" too close, you'll not make max voltage (depends on gap) that close.
Well, the smaller the gap, the less voltage needed to create a spark across the gap. The larger the gap, the more wear on the plug. The spec gap is there to balance this to create a complete burn of the fuel.
This is going off the top of my head and its late, but I think thats how it works.
This is going off the top of my head and its late, but I think thats how it works.
andreslobo
Hard-core CEG'er
pretty much anything will work
pretty much anything will work
Back in the bad old days of points and not so strong coils we had to gap plugs pretty small to ensure that there was a spark. But now days, the spark is strong and the timing consistent. Pretty much any gap will work, from 0.01 to 0.1.
Now days, I run em to 100,000 miles and toss in a new set, usually just a visual on the gap to make certain there is one.
Unless you have no gap or the side electrode is missing, you ignition system will fire the mixture. Don't sweat it.
pretty much anything will work
Back in the bad old days of points and not so strong coils we had to gap plugs pretty small to ensure that there was a spark. But now days, the spark is strong and the timing consistent. Pretty much any gap will work, from 0.01 to 0.1.
Now days, I run em to 100,000 miles and toss in a new set, usually just a visual on the gap to make certain there is one.
Unless you have no gap or the side electrode is missing, you ignition system will fire the mixture. Don't sweat it.
Now days, I run em to 100,000 miles and toss in a new set, usually just a visual on the gap to make certain there is one.
Unless you have no gap or the side electrode is missing, you ignition system will fire the mixture. Don't sweat it.
i would not run them that long and I would not just eyeball the gap.
I pulled plugs from mine that had ~100k on them. 2 plugs, #3 and 4 where trashed. The gap was .080. I regapped and I felt the car ran smoother and it got slightly better gas milage.
also there is no reason to run any gap but the factory recommend gap, imho.
hectik1
The Hispanic Hellion
I gapped mine at .045.:shrug:
mcgarvey
Veteran CEG'er
The plug may still fire when worn or improperly gapped, but it puts extra stress on the coil because the required voltage is higher. Price of 4 spark plugs and gapping tool < price of ignition coil.
I would never use a gap of .010" on anything, the coil makes more voltage the wider the gap until coil not able to anymore. A wider gap will smooth the idle up as long as coils can handle it. It can even affect F/A ratio that engine wants. The effect of weak spark can appear very easily to be too rich mixture. Have changed motorcycle ignition from one that was stock, .028" gap, ran seemingly well. Built a custom setup out of GM ignition modules and twin tower coils off Cavalier, gapped at .050". Idle smoothed up a bunch and plugs went very light in color, engine able to stand more fuel then. When jetted up, motor picked up added power.
mcgarvey
Veteran CEG'er
Exactly. When the transistor in the coil opens the circuit, the secondary voltage has to go somewhere. Normally it goes through the plug wire, across the plug gap, and then back to ground (in waste spark systems, across the other plug gap as well- but that's another story). When the gap is too great either from improper gapping or wear, the secondary voltage has no place to go and can't find ground. Instead it jumps around in the coil and can cause it to burn out or carbon track. 40,000 volts really, really, really wants to find ground and will damage lots of stuff in its path if it can't.
andreslobo
Hard-core CEG'er
gap is not that important
gap is not that important
The intent of the message is that gap is not critical, as long as you are in the range that will allow a spark.
Factory recommended gap +/- .030 will not be noticable to most drivers. To be concerned about plug gap out of tolerance by .010" is wasted brain cells or someone has nothing more important to worry about.
The current ignition systems are great, they will likely jump a gap greater than you could reasonably get with a spark plug. As long as the spark jumps the gap, it'll not put any more 'strain' on the coils. The firing voltage of the coil is fixed by the input not the plug gap. Once that air in the combustion chamber starts ionizing, it'll not notice a few extra thousands of gap.
In he bad old days, you most certainly would have gapped plugs at .010, otherwise your small motor would never have run. Try an old (1950s) outboard with anything more than .015 and try and start it. It won't happen, those ignition systems were pretty bad.
gap is not that important
The intent of the message is that gap is not critical, as long as you are in the range that will allow a spark.
Factory recommended gap +/- .030 will not be noticable to most drivers. To be concerned about plug gap out of tolerance by .010" is wasted brain cells or someone has nothing more important to worry about.
The current ignition systems are great, they will likely jump a gap greater than you could reasonably get with a spark plug. As long as the spark jumps the gap, it'll not put any more 'strain' on the coils. The firing voltage of the coil is fixed by the input not the plug gap. Once that air in the combustion chamber starts ionizing, it'll not notice a few extra thousands of gap.
In he bad old days, you most certainly would have gapped plugs at .010, otherwise your small motor would never have run. Try an old (1950s) outboard with anything more than .015 and try and start it. It won't happen, those ignition systems were pretty bad.
The firing voltage POTENTIAL of the coil is fixed by the input. If you do not open the gap, you are not exploiting all of it. Only enough voltage used to ionize the air and jump gap, wider the gap more of that potential must be used to cross it. It's not voltage if you leave it lying in the box not to be used. On that same bike I spoke of, started out with the stock .028" gap, gradually opened bigger and bigger. Engine idle got smoother and smoother the more I opened it. Same with plugs, they got lighter and lighter in color. At least until I got nervous enough to jet up some and color them some more. That used to be the test on race cars, doesn't matter what ignition claim for output (input?), you gradually increased the gap more and more to see when they choked. One that fired wider gap considered better ignition. Somewhere around the mid-late seventies there was a push for more spark when some smallblock pro stock people realized a firm 8-10 horse increase from what at the time was considered to be superwide spark gap.
69Boss302
Has mile high skills
no plug comes pre-gapped for a specific installation.
gap is 0.050"
Actually, there are plugs that come pre-gapped. And there are some plugs that can't be gapped or should not be gapped per manufacturers suggestion. You'll most likely see those as the +2 or +4 plugs and some special use plugs.
Ever seen the small hand press used to set old style side electrodes? You used a wire gauge as set point and pressed in the electrode sideways. I had a good friend that had a '70 Boss, when done we had that thing where it ran 10.80 1/4 mile @ 130+ mph. Weiand tunnel ram, 2X4 750 Holley DP, 324 degree .600+ lift, 4 speed toploader with the good low gear, 6.14 gears. Car traded to someone else then ran 11.0s and teens with one cylinder not working. That guy ran it like that 2 race weekends trying to fix until finally discovered somewhere in there had broken a rod. Piston stuck at TDC and lower rod half bent slightly off into it's paired brother. Couldn't believe engine didn't blow to smithereens. We did a heck of a lot of street racing in that car. I still can remember the strange intake sound that engine had, unlike any other V-8 I have heard. Identified it even in the dark at the end of dragstrip.
Actually, there are plugs that come pre-gapped. And there are some plugs that can't be gapped or should not be gapped per manufacturers suggestion. You'll most likely see those as the +2 or +4 plugs and some special use plugs.
very well. I have always heard that plug gaps had to be set. well they should be check anyway.
I can understand that those +2 or +4 plugs might not get gapped, but no one here uses that crap anyway so its a non-issue as far as I am concerned.
They WON'T get gapped, you can't do it. They are machined when made. I love all those airbrushed pics showing fire jumping from all four points at once. Whatta scam. My dad fell for it once in the mid sixties with "Fire Injector" plugs. Same idea but 8 points to jump from. He used 'em in his '64 Sport Fury street racer (426 wedge, big cam, 2X4 bbl.) drove them to work that day, came back, yanked them out and threw them out in the field behind house. Said they were junk.