Autolite 104s gapped at .055. You'll never go back...

 

This is what I run, but have some people say they run .60 or even .65 sometimes, anyone have input on that?

 

Autolite 104s are dirt cheap (less than $2 a plug), copper core, and run better than pretty much anything out there. You can't beat that. Like TolusD said, gap them to .050 - .055 and you're golden. People have tried the more expensive NGK TR7s, Denso Iridiums, and other high dollar plugs only to come right back to the 104s. They're about the best out there, especially for the price.

 

what about staying with the stock double plats ??

 

There really isn't a point when they are 2-3 times the price of the 104s and the 104s run better. Also, the 104s can be found at any autozone or advance vs having to go to a dealership for the motorcrafts and a lot of times them not having them in stock. At least that typically the situation at the dealers near me.

 

hmm im not sure what to do now because im basically due to change mine and I was going to hit steve tousley up for a set. I guess i dont know what kind of mileage you get out of 104's but i sure like the 100,000 mile double plats.

 

I'm running Autolite 103 coppers (colder spark 103s since I'm boosted) and I still get 32-34mpg highway with being boosted and a 4.06 final gear. If anything, mpg improved with them. The copper plugs are more conductive and less brittle than platinum which makes for more resistence to heat and detonation while providing a more responsive spark. Whether you are bone stock or have a 600+whp built monster, Autolite coppers work amazing in our cars.

As for longevity, they don't last as long. I wouldn't suggest going more than 15k miles on them but when they cost less than $8 for 4 of them, that's dirt cheap. I change mine every other oil change but I'm also boosted and beat on my car so they take more abuse.

 

For the cost and time of replacing 104s only after 15k miles, to me it seems like it would be more cost effective just to go with a stock set of plugs.(for my application)

 

Time? It takes 15 min and that includes gapping. lol To each their own. You'd be spending $8 once a year, if that.

 

well today i changed them, got the 104's an gapped them to .055. as it stands right now the best thing i did to the car ( havent done much). but when taking the old plugs out, cylinder 1, and 2.... I think have issues i dont know tho. cylinder 1's plug was rusted out at the threads, and cylinder 2's had oil in the threads. also the other one's from 3 and 4 where wayyy off with the gap the first 2 were gapped i think at .052 and the others were .057 and .058? i guess its just fords crappy factory workers....

 

well today i changed them, got the 104's an gapped them to .055. as it stands right now the best thing i did to the car ( havent done much). but when taking the old plugs out, cylinder 1, and 2.... I think have issues i dont know tho. cylinder 1's plug was rusted out at the threads, and cylinder 2's had oil in the threads. also the other one's from 3 and 4 where wayyy off with the gap the first 2 were gapped i think at .052 and the others were .057 and .058? i guess its just fords crappy factory workers....

That's the effects of platinum plugs over time. The metal is more brittle and therefore known to have the gap open up or close over time. They may have all started at .045 gap but have ended up where they are now. As for the oil, as long as you are not seeing oil out of your exhaust, you are fine. Sometimes the valve cover gaskets on the Duratecs will leak a little bit and that oil my drip down by the plug and get on the threads. The rust is normal really, especially for having been in there as long as they were. Some moisture can get by the boots of the COPs and that combined with the heat in the head will make them rust.

 

yea the guy at autozone was like the plats are the way to go scince their oem, an i was like i have heard they suck an never but iridium or platinum. then he said i will lose gas milage if i go to copper an the spark wont be as hot? is that true, i was just thinking he was trying to talk me into the more expensive plug scince they were 6 per plug vs 2 dollars of the 104's.

 

They don't create more heat. No matter the spark plug metal, the heat range of the plug is controlled by the resistor. You will see higher temps from platinum and iridium plugs compared to coppers of the same heat range resistor but this is not because their heat range is higher. Whether the plugs are Copper 104s or Iridium XP104s, the heat range is the same. What sets them apart is that copper is better at dispersing heat than both platinum and iridium. Copper is both more conductive and less brittle therefore it's much easier to gap them and have them stay gapped for their lifespan.

Basic horsepower 101 says that more heat typically equals more power. This is a good rule of thumb but is not always true and can vary depending on your engine setup. Too much heat results in detonation which usually results in engine failure. For high compression or forced induction applications, copper plugs are commonly used because the heat dispersion properties helps with knock resistance allowing for more power to be made, and because the more conductive properties of the copper helps to keep the spark from being blown out. The majority of the boosted guys on here use Autolite 103 copper plugs (one step colder than the 104s).

Platinum plugs are good for longevity, but they sacrifice strength and knock resistance. Copper plugs are good for strength and knock resistance, but they sacrifice longevity and ability to make high heat. Iridium plugs are good for high heat and higher octane, but sacrifice knock resistance and strength. Silver plugs are good for knock resistance, higher octane, higher heat, and resistant to corrosion, but sacrifice strength and longevity. Silver plugs are usually very exspensive and are pure race applications only using corrossive fuels such as methanol. I think Accel actually makes a set for the Duratec.

Why are Autolite coppers so good in our cars? Well... they just are. lol Even on a bone stock car, it's been a known fact that the coppers run smoother and seem to make more power.

 

I believe that the working electrodes are not copper, Just the metal inside the ceramic. Believe me, a spark that can jump l/4 inch isn't going to be slowed down by a steel allow electrode....

 

I believe that the working electrodes are not copper, Just the metal inside the ceramic. Believe me, a spark that can jump l/4 inch isn't going to be slowed down by a steel allow electrode....

I was going to say .055 is not 1/4 but I see you put "l/4" inch? If you did mean 1/4 inch that's .250 that's a pretty big gap. .055 is less than 1/16.

Well anyway, I changed my plugs to the 104s and yea big difference. The old plugs were kinda worn but I had them 20K miles ago and the feel is much different from then. Don't believe the hype of fancy plugs cheaper is better in this case. Idle is much better and the car starts right up.

Side note, I noticed that there was some blowby on 2 of the old spark plugs, they had that nice coffee with extra cream smoke look up past the threads to the drive part and some of the boot. It was the middle cylinders, they were all hard to turn out.

 

Looks like ill be buying autolite 104's. pretty convincing haha

 

Autolite dbl plats (or NGK, for that matter) have lower resistance than the 104 coppers do... it's a small difference, but at high rpms that means something. The dbl plats generate less internal heat, due to the lower resistance. Also, changing them far less often saves the threads on aluminum heads. If your engine is stock or close to it, dbl plats can't be beat... for price (last much longer), for performance (resistance), or for security (thread protection).

 

Please explain to me then why the copper 104s have proven to perform better with the Duratecs in numerous trials over the years? I've seen twice as many double plats come apart and fail than I have coppers.

 

What "proof" would that be? A Duratec is an internal combustion system like every other engine, there is no special magic that causes a Duratec to "need" copper plugs. If a boosted Duratec (or Zetec, SPI) runs better on copper than dbl plats, that's cool... but an NA Duratec is just an NA Duratec. For that the factory choice is best. And I've seen Iridium electrodes erode away, but I've never seen a dbl plat fall apart in a stock engine.

 

What "proof" would that be? A Duratec is an internal combustion system like every other engine, there is no special magic that causes a Duratec to "need" copper plugs. If a boosted Duratec (or Zetec, SPI) runs better on copper than dbl plats, that's cool... but an NA Duratec is just an NA Duratec. For that the factory choice is best. And I've seen Iridium electrodes erode away, but I've never seen a dbl plat fall apart in a stock engine.

The numerous reviews of the Autolite 104s idling smoother, having better acceleration, and better mpg than the double plats, even on bone stock engines. There's even a dyno chart floating around somewhere showing consistantly 2-3whp better with Autolite 104s gapped at .055 than the stock double plats on the same dyno, same day, just the 20 min between changing the plugs out. It was years ago and can't remember if it was on this site or FF.

 

I would definitely have to see that dyno sheet before I'd believe any resistor spark plug can gain you over 2% WHP on a stock engine... pretty much any engine. I agree that gapping effects performance, but center electrode... not as much.

 

Dynos and extra HP nothwithstanding and regardless of any sweeping indictments or generalizations, my Focus runs better (smoother idle, better throttle feel at the pedal) with 104s gapped at .055 than it does with anything else that I've tried. It runs light years better than it ever did with the factory iridiums. Why that is doesn't matter to me at all and I don't think it's unreasonable to suggest a $5 investment in a set of 104s to someone curious about spark plugs and their potential impact on performance.

Also, the suggestion the factory choice is best 100% of the time when there's no boost is almost adorable given the overwhelming number of contradicary testimonials on this site and every other Focus site in existence. Your inability to explain why a thing is happening within the confines of your personal experiences and knowledge shouldn't make you feel like you have carte blanche to effectively insult and condescend to everyone who has posted a testimonial about improvements after installing 104s.


While we're making requests to see proof in the form of dynos, why don't you post some that prove your contention that OEM iridiums or double plats are the best choice for NA Duratecs compared to 104s. I would honestly like to see that because it might shed some light on why 104s actually DO make most Foci run better.

 

G-force. I'm with you on this. My 2.3 didn't really run better in any way with 104's. Also note, both plugs have copper cores. I will go with the Ford engineers on this one.

 

G-force. I'm with you on this. My 2.3 didn't really run better in any way with 104's. Also note, both plugs have copper cores. I will go with the Ford engineers on this one.

This is the core of this whole debate as far as I'm concerned. Some run better with 104s and some don't. That's clear from the available evidence but it causes a huge problem when everyone believes that their personal experience is the only one that's valid.

My only advice and opinion on this issue is that it's a $5 experiment that will either make things better or not. There's no real reason not to try it and see what results you get.


As for siding with Ford's engineers, if you ever meet one maybe you can ask him why 104s improve the idle and pedal feel in some Foci and not others.

 

In my experience stock plugs are the best. And I run 104s for 2 years. With stock plugs you don't need to worry about gapping and keeping track when you need to replace them. Because with 104s you would need to change them once a year. I've actually went through 4-5 sets of 104s trying out different gaps and let me tell you it runs the best with the stock plugs.

 

You're obviously not the only person that's had that exact experience but plenty of us have had the exact opposite experience. I had stock iridiums in my ST when I bought it and not only did it idle like a busted chainsaw, it would routinely refuse to start unless I held the key down for almost 20 seconds. I took it back to the dealer twice for this and they assured me that they couldn't find anything wrong.

Someone on FJ suggested that I change my plugs so I bought a set of OEMs and put them in and it didn't help at all. After that I went to Autozone and bought 4 double platinums, 4 iridiums from NGK and 4 104s. I spent about 3 hours after that testing spark plugs in my car. I tested the 104's last and not only did they smooth out my idle, my car started in less than second consistently and it has ever since.

That was in about October of 2005 and I've not had any problems with the 104s at all. Just for this thread though, I'm seriously considering picking up a set of OEM Motorcraft iridiums next week and making a vid of my car running them versus the 104s. I'm too busy with class this week or I would do it this weekend as I have to change my oil anyway.

 

Cool on you, Tolus :thumbup:. I've got an '05 ST and don't like the long crank time to get the car running. I installed new OEM plugs (even though the factory iridiums didn't have a whole lot of miles on them). When that didn't solve the problem, I took it to a dealership to have them re-map the PCM according to a tech bulletin supposedly related to the issue. That didn't help either.

Nothing to lose other than a few bucks, a little time and the more frequent maint schedule (but that's cool). If it reduces crankover time and smooths out the idle, it'll be well worth it...

 

I run NGK and they seem good!!

 

Just by way of a follow-up. Truth-in-forum'ing kinda thing. After a week to test: I had good luck with the Autolite 104s for smoothing out what was previously a less than perfectly steady idle. Impressive.

No luck with taking care of the intermittent long crank time (sometimes it just wants to turnover for several seconds I guess). It is what it is. Luckily, starting the car isn't part of the race... just kidding. Mostly. :evilgrin:

 

I realize this is an Old thread but just had to ask. On my Foci's they have the 2.0L Zetec engine and I am running NGK's, but I have read this thread and really am considering going to the Autolite. My question is does my 2.0L use the AP104 also or is this Plug only for the 2.3L ?

Thanks in advance,
allcruisen