Using AC Delco spark-plugs gapped at the stock setting .045, by gapping the plug larger will this create a better burn / or better performance from a stock engine??

I know this isn't going to make 10HP, but just wanna know if anyone has gapped their plugs on a V6 fiero and their thoughts on it.

And what are the ups and downs of playing with setting the gap for the fiero.

TIA,

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fierogt28

88 GT, loaded, 5-speed

After I added an MSD coil, 8mm MSD helicoil plug wires, an MSD 6aL box, and platinum plugs, I played with the spark plug gaps trying to get as much power as I could...

I had it anywhere from .045 up to .060. My thinking was, that the MSD ignition parts should create a "hotter" spark, and would be more able to jump the bigger gap. Bigger gap equals bigger spark. Bigger spark equals more fire.... (go ahead and tell me im wrong) but that was my thinking. I have no dyno tuning numbers or track numbers for proof, but I do remember the car running better with .060 gap and that ignition. A friend of mine with the same motor and stock ignition, ran like crap with .060 plug gap.


I say to keep the STOCK motor and STOCK plugs set at STOCK settings.
Thats how it should be.
Chris

There will be no gain with an increase gap,,you want to have as uniform gap as posible each plug equal check electrodes to make sure they are centered not crooked,,be precise when you measure !! a wire gap gage is best,, but the new solid gappers are OK,, mark spark plugs so you know where electrode is and index spark plugs for best performance many of the simple things are now overlooked ,,When i was a motorcycle mechanic building race engines ,,you negleted the small stuff at the risk of loosing..
avoid expensive fancy dan multi electrode spark plugs..
use Ac delco,, or if you do not mind jap products NGK .. Distributor equipped engines need and love top quality plug wires..its a hot fiery romance...
The expensive spark plugs with coils ,ect in the plugs are no good on the V 6 unless you modify to run up to 6000 rpm.

[This message has been edited by uhlanstan (edited 02-24-2009).]

NO !!!!!!!!!!!!!!!!!!!!!! Any gain is in the imagination of the person doing the GAP fooling around.
Ed

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The gain doesn't necessarily come from the gap in the plugs, but it's an accessory to it. You do need a hotter ignition coil obviously, but by advancing the timing, you can in turn create more power.

It's been years, literally, since I've done this since my Fiero hasn't run, and my 73 Olds Cutlass and my 73 VW Bus... well... I've never even touched the distributor since I've owned them, and I've had the Bus for 6 years already and they run fine... hah.

But, basically... you can increase power in your car by increasing the gap on the spark plugs. In order to efficiently get more power from this (it's not much, mind you), you need to also advance the timing. When you advance the timing, you also need to go to a higher octane.

As you know (or should, at least), higher octane does not create more power... but some cars require a higher octane, while others do not. A big old 80s Chevy Pickup certainly does NOT require high octane fuel. Neither does a stock Pontiac Fiero.

A Turbo Solstice, certainly DOES require higher octane fuel, but has a series of knock sensors to prevent predetonation should the driver decide to put 87 octane in there.

In any case, you can get more power using the higher octane and a larger spark-plug gap if you advance the timing, and go with a higher octane fuel.

I'm not talking about a lot of power, and I'm not talking about a whole hell of a lot of timing advance either, but it is a proven "modification".

I see it on Two Guys Garage, Muscle Car, and Horsepower TV every now and then.


Honestly, it's been years since my Fiero ran right (whiped out a cam lobe, just haven't gotten around to it), so I can't remember if it improves performance on the top end, or the bottom end...

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Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convt. (Wife's)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6
1981 EZ-GO Xi875-A "Miami Dolphins" Medical Cart
1973 Volkswagen Type-2 Transporter
1973 Oldsmobile Cutlass Supreme 350

about gapping, you have it backwards. Smaller the gap, the better it is, to an extent. I was tought to gap in 0.002" increments. You want to go small as possible without being too small, on a performance engine. Also, for performance, you cut the ground strap so its sideways, here let me ASCII draw that, if I can.
STOCK:
NO ASCII D: Well here are images:



CUT GROUND STRAP:



race cars use that kind of plug, or make their own like that out of cheap plugs, because they provide a better spark and flame front.

The reason the gap is like that is for the consistant spark, plus, why you go small not large, is turbulence inside of the engine. Air turbulence can blow out the arc of the spark plug. Too big, you get missfires from the spark being blown out! Keep it small, its better to undergap than overgap. Sparks don't just happen, by the way, it has to ionize the air first, then jump across the ionized gap. if the air is going every which way, it makes the air resistance much much higher, decreasing spark efficiency

EDIT: MY ASCII FAILED!

[This message has been edited by Racing_Master (edited 02-26-2009).]

quote Originally posted by Racing_Master: about gapping, you have it backwards. Smaller the gap, the better it is, to an extent. I was tought to gap in 0.002" increments. You want to go small as possible without being too small, on a performance engine. Also, for performance, you cut the ground strap so its sideways, here let me ASCII draw that, if I can. STOCK: NO ASCII D: Well here are images: CUT GROUND STRAP: race cars use that kind of plug, or make their own like that out of cheap plugs, because they provide a better spark and flame front. The reason the gap is like that is for the consistant spark, plus, why you go small not large, is turbulence inside of the engine. Air turbulence can blow out the arc of the spark plug. Too big, you get missfires from the spark being blown out! Keep it small, its better to undergap than overgap. Sparks don't just happen, by the way, it has to ionize the air first, then jump across the ionized gap. if the air is going every which way, it makes the air resistance much much higher, decreasing spark efficiency EDIT: MY ASCII FAILED!

I respectfully disagree... but also agree... the difference is the type of engine it's going into. The race-car drivers do that becasue the shorter the distance, the higher the rpms they can get and the shorter the distance the spark needs to arc.

For normal day to day engines... the bigger gap would be better, especially in our Fiero's which will never see above 5,800 rpms (realistically).

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Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convt. (Wife's)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6
1981 EZ-GO Xi875-A "Miami Dolphins" Medical Cart
1973 Volkswagen Type-2 Transporter
1973 Oldsmobile Cutlass Supreme 350

quote Originally posted by 82-T/A [At Work]: I respectfully disagree... but also agree... the difference is the type of engine it's going into. The race-car drivers do that becasue the shorter the distance, the higher the rpms they can get and the shorter the distance the spark needs to arc. For normal day to day engines... the bigger gap would be better, especially in our Fiero's which will never see above 5,800 rpms (realistically).

And i respectfully disagree, but also agree, since a gap on a daily driver should be conservative, mind you. Though, a regular car and a race car can both see the effect of quenching. I have one in my shop right now, with too large of a gap, misfires when cold. Ive seen that its best to leave the gap @~0.040-0.060 dependant on the engine its being installed into. if there is no gap specification on a stock engine, I usually gap to ~0.045-0.050 as a safe number. if I were doing a performance engine, however, that gap would be smaller, and the ground strap cut back. But this is just my 2 cents worth. Here is what NGK has to say about quenching, and a couple more images:

quote Quenching is when the heat generated by the spark is absorbed by the center or ground electrodes instead of igniting the air/fuel mixture. To understand quenching and how it is reduced it is first necessary to review the basic purpose of the spark plug is to ignite the air fuel mixture in the combustion chamber. To do this your vehicle ignition system generates tens of thousands of volts to jump the gap between the center and ground electrodes. However it is good to know that it is not the actual electricity that ignites the air fuel mixture, it is the heat energy generated by that electricity or spark. Therefore when you are creating the spark you want as much of the heat from that spark to be used to ignite the air fuel mixture and not have the heat from that spark be re-absorbed by the center and ground electrodes. Thus NGK makes a variety of designs(cut back ground electrodes, V-groove center electrodes, fine wire center and ground electrodes) all resist quenching by reducing the contact(surface) area between the electrodes and the flame nucleus.

CUT BACK GROUND:



ANGLED GROUND:



REGULAR GROUND:

larger gaps by themselves - wont change alot - might be measurable
a larger gap allows for slightly more timing

rarely do things by themselves give gains. they are part of a package. same with this.
a stronger coil, larger gap & increased timing - do the whole package.

we dont have to worry about flameout, or the fual/air mix being way to dense due to high boost or high compression. a larger spark does burst the fuel/air mix faster.

I own a GM vehicle which factory, recommends a spark plug gap of .060". No I don't drive a Buick GNX or Corvette ZR-1 or anything high performance at all, rather, I drive a Bonneville with a Pontiac 301 V8, that makes about 140 BHP brand new.

The reason why GM recommended a spark plug gap of this size in that time frame was to help light off the leaner mixture due to tightening emissions regulations of the day, it had nothing to do with performance. At such a large gap, the cap and rotor would get carbon'ed up very quickly, to the point of needing to clean them, if not, change them every time plugs were changed, stock coils also did not last very long at that gap. Closing the gap to .045" found improved performance.

Does the same theory apply to 2.5L-4cyl motors? When I replaced my plugs after I got my car, the parts people told me the gap should be 0.060. The plugs when I pulled them were anywhere from 0.035 to 0.080! (No wonder the thing ran but like crap) If I re-gap my plugs to 0.045, would I get a performance increase and maybe some more fuel efficiency?

Caution...
increasing gap on the spark plugs = increasing coil and module heat = even burn out

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

quote Originally posted by LT-5Fiero: I own a GM vehicle which factory, recommends a spark plug gap of .060". No I don't drive a Buick GNX or Corvette ZR-1 or anything high performance at all, rather, I drive a Bonneville with a Pontiac 301 V8, that makes about 140 BHP brand new. The reason why GM recommended a spark plug gap of this size in that time frame was to help light off the leaner mixture due to tightening emissions regulations of the day, it had nothing to do with performance. At such a large gap, the cap and rotor would get carbon'ed up very quickly, to the point of needing to clean them, if not, change them every time plugs were changed, stock coils also did not last very long at that gap. Closing the gap to .045" found improved performance.

yes, I would not doubt that at all. the reason is: poor coil. it was to weak, and would make weak spark.
The stock Fiero coil has the same problem. it gets weak at around 3500 RPM. you open up the gap - and it will get weak sooner.
some good wires help too.

poeple dont put strong coils & low resistance wire ignition wires on because the look cool. it is because they help. help make big strong spark.

doing just one aspect of the ignition system usually dont help much. always start at the coil. then the wires. then the gaps. then adjust timing to take advantage. because a bigger spark makes a faster boom, and a faster boom requires a change in timing. and, it really does change the timing. need to keep in mind the speeds at which things happen in a motor. just picture a 600 RPM idle. how many booms a second is that?

This is makin' me wanna go out and make sure my spark plugs are all gapped to .045 - .050. I need a flat feeler gauge though. This little $.99 circular gap gauge can't be the most accurate thing in the world...

quote Originally posted by Brocephus: This is makin' me wanna go out and make sure my spark plugs are all gapped to .045 - .050. I need a flat feeler gauge though. This little $.99 circular gap gauge can't be the most accurate thing in the world...

no, not a flat feeler guage, you need a wire feeler guage, that is how you check plug gaps. Flats arent accurate either, at least on plugs

Gapping a duke 2.5 at 045 will make it run lousy ,,use .060
the round gap tool works excellent !! the wire gapper is best but for most engines the round tool is great
make sure the spark plugs are gapped properly and the electrod is in perfect alignment
Make sure the electrode is in perfect alignment,double check .
the duke is simple ,, needs simple tune up work
check out some of the recent post on improving duke performance

My understanding is from physics, where the resistance in the air gap due to the density of the air determines the intensity of the spark for a given system. Increasing the gap above stock recommendation at some point will weaken the spark to a point of fouling the plug or causing it not to fire at all because the spark has to be within a certain intensity range to jump the gap and ignite the airfuel mix, for example a weak yellow in color spark vs an intense blue in color spark. You can experiment on a lawnmower engine which I did to discover this long ago before reading about it. I demonstrated that a yellow spark from an overly gapped plug placed in a small bit of fuel could not ignite it. I also discovered that an overly gapped plug that could ignite the fuel would in short time foul the plug (experimented on a go-kart). As several have already mentioned, the entire ignition system needs to be addressed. If you widen the gap significantly above recommendations, you should probably increase the spark energy with high voltage coils and high performance wires, otherwise you likely stand to gain more with the same gap and more timing advance than the other way around.

Here is a copy and paste from some info I have in a pdf from a source I can't find at the moment that helped me realize I needed to close my plug gap:

Amplifying Spark Energy
There are several ways to amplify the spark. This can be accomplished either by making the spark duration longer or by increasing the intensity of the spark. Firing the plugs multiple times on each cycle increases Spark duration. Spark intensity is increased by shortening the duration of the spark and increasing voltage at the plug. It is necessary to amplify the spark on engines with high cylinder pressures, such as forced-induction or nitrous oxide applications. On engines that utilize bolt-on modifications with no internal engine modifications, an enhanced ignition system is rarely needed.

Spark Plugs
Spark plug selection affects engine performance. On forced induction engines, it is critical that the proper heat range and gap is used. Heat range refers to the ability of the spark plug to conduct heat away from the electrode to the engine. A plug that has high thermal conductivity has a short insulator that comes in contact with a large portion of the metallic plug shell. This large area allows the combustion heat to be carried through the plug shell to the cooling jacket of the cylinder head. In the case of a hot plug, the insulator is recessed deeply into the plug shell with minimal contact to the shell. The plug has low thermal conductivity due to the lack of contact with the shell. The nose of the insulator should operate at between 400 – 850 degrees C. Temperatures above 400 degrees C are desirable because at higher temperatures deposits from carbon, lead or soot are burnt off. Temperatures of 850 degrees C and over should not be exceeded because this is typically the point where detonation or auto ignition can occur. Lower heat range plugs have a higher resistance to auto ignition while higher heat range plugs have less tendency to foul.

The spark plug gap on forced induction engines should be reduced REGARDLESS of the type of ignition system. We have read many instruction manuals for aftermarket ignition systems that recommend that the plug gap be opened up for better flame propagation. Although this recommendation may have had some merit when vehicles had carburetors, it does not apply to modern engines with electronic engine management systems. The smaller gap on forced-induction engines requires less spark energy to arc across the ground and the electrode and has a lesser tendency to misfire under the extreme pressures of a racing engine combustion chamber. Also there are spark plugs made with exotic fine wire highly conductive center electrodes that require less energy to fire such as the Denso Iridium that are well suited to racing conditions. The following is a chart of gap sizes for various engines on gasoline:
Naturally Aspirated up to 11.0:1 CR 1.1mm (.044”)
Naturally Aspirated 11.0:1 to 14.0: 1.8mm (.032”)
Forced Induction to 20-PSI .7mm (.028”)
Forced Induction to 40-PSI .6mm (.022”)

Unless I am mistaken, a certain amperage has to build up to jump the gap. More gap takes mor amps, meaning more time, thus making the spark a bit later. To run more gap takes more advance. Same with the old points. Incorrect gap messes with the timing. I'm pretty sure the factory did a fair amount of tinkering to get the factory specs.

quote Originally posted by weaselbeak: Unless I am mistaken, a certain amperage has to build up to jump the gap. More gap takes mor amps, meaning more time, thus making the spark a bit later. To run more gap takes more advance. Same with the old points. Incorrect gap messes with the timing. I'm pretty sure the factory did a fair amount of tinkering to get the factory specs.

In the case of my DD, they didn't and since the 301 and Duke were co-projects, I am wary of running a .060" on a Duke.

quote Originally posted by weaselbeak: Unless I am mistaken, a certain amperage has to build up to jump the gap. More gap takes mor amps, meaning more time, thus making the spark a bit later. To run more gap takes more advance. Same with the old points. Incorrect gap messes with the timing. I'm pretty sure the factory did a fair amount of tinkering to get the factory specs.

its voltage, not amperage. The coil takes 12v and makes it 50,000v or more, and in turn, lowers its amperage. You can survive getting shocked by spark plug wires, because they are low amperage, its not enough to kill you. The voltage hurts like a M@!)er F#@ker. Can also leave you sterile (Yay, painful birth control) for 3 days, under certain conditions... if it exits the body below the belt but above the thighs..... >.> you get the hint.

My understanding about factory gap is this:

The Duke was made for more fuel economy, its intake charge is not extremely dense nor is it really turbulent. The gap was spread to 0.060 for the reason that it provides a more broad flame front, meaning it gets better emmisions from burning everything that enters the non turbulent cylinder, and the not so dense air charge. While if you turbocharged a duke, you would NOT run that gap, at all. I would start at a gap of 0.020 and gap up slowly by 0.002 incriments till the desired gap is acheived, genreally using a dyno to help you out with finding the gap. Problem with running normal plugs is they are suseptible to quenching, the heat is trapped in by the ground strap. Cut the ground strap, gap the cut back ground strap properly, you can close the gap, have low quench, and a really hot spark, and a really good, controlled flame front.

We adhere to stock gaps specs unless a high energy igniton is used. Then we increase the gap a few thousandths as there is sufficient spark energy to fire the plug with the high tech CD multispark ignitions. With a .060" gap on my turbocharged GT running 9 psi of boost, I've never experienced spark blowout at the 5600 RPM redline that I use.
Generally small gaps produce a short fat spark ( that won't blow out when racing) while large gaps produce a longer thin spark that is conducive to mileage. However when you install a high energy performance ignition the equation changes.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE WILDCAT"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Run the recommended factory gap unless you have a lot of time to experiment
you can not go wrong with .045 on the V6 ... and .060 on the 4 cyl duke