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Discussion Starter #1
As many of you know, this TCCoA newbie is trying to get familiar with his T-Bird. Up next are spark plugs and after searching the forums for a little bit, I know what the options are out there, but I don't know what to choose from. The jist of what I've got though is that coppers are better performing but very short lifespan, platinums slightly less performance but much longer lifespan. What about iridiums? I've seen them mentioned, but I don't recall reading anything about their lifespan and performance in relation to platinums and coppers. There are "hot" and "cold" plugs that act differently. I also read about plug wires and how some are real good (bosch, autolite, motorcraft, MSD) and other brand are real cheap and don't let the engine run to OE specification. So much stuff I can't remember to regurgitate right now. As for the spark plugs I've read people use they are...

Autolite:
- AR94
- 103
- 764

NGK:
- TR55
- TR6
- V-Power

Motorcraft:
- SP432
- APP104
- SP433

Bosch:
- (I read at least one post, but could not find it again to list here)

Here are some of the threads I thought were most relevant and / or informative about spark plugs but still doesn't help me pick what spark plugs I should be using.

http://forums.tccoa.com/showthread.php?t=26582&highlight=spark+plugs
http://forums.tccoa.com/showthread.php?t=142457&highlight=spark+plugs
http://forums.tccoa.com/showthread.php?t=138950
http://forums.tccoa.com/showthread.php?t=140806&highlight=spark+plugs
http://forums.tccoa.com/showthread.php?t=142496&highlight=spark+plugs

I guess the information I'm looking for is, what plugs are the best performing with the longest longevity possible. If all coppers last no more than 20k miles but perform great, and all platinums don't perform very well but last a long time, is there something in the middle? I don't want to be replacing spark plugs all the time as I drive ~100 miles a day round-trip to and from work.
 

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I get the autolite xp iridiums for my waste spark vehicles as they also have platinum on the ground strap. I get them when there is a rebate if possible. Double platinum is a must for longevity. I had some junk BW wires, frpp wires nearly the same price and better quality.

I don't recall the new spxxx motorcraft part number for the double platinums, appxxx for autolite doubles.

If stock replacement no need to go with a colder plug. Only if you have a tune and it is recommended that you get a colder plug do you need to do that.
 

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Ive never ran plats or higher, I just run autolite coppers or Recently went with NGK TR55 coppers. The only difference ive noticed between these two, is my idle runs lower with the NGK I run right over 500rpm unlike the autolites. Autolites It was around 750-800ish, Sitting right above 500rpm with the ngk I get no rough idle and it feels like my car isn't even running. Why the car runs different between the 2 , I have no clue lol
 

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Discussion Starter #6
Are all NGK plugs already pre-gaped for our cars, or do they have to be properly gaped? I know that NGK plugs come pre-gaped for Japanese cars such as Hondas and Mazdas. But are they already pre-gaped for our cars as well? If so, are there any other plug brands that are pre-gapped? It really shouldn't matter if they are pre-gaped or not, but I just want to know this part.

What about the spark performance differences between platinum and iridium plugs? I don't recall reading anything on this when I was searching about the different spark plugs?

And what about the longevity of platinum and iridium plugs? I know both last longer than copper, but how do they last in relation to each other?
 

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ALL plugs should be properly gapped before installation.
 

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What about the spark performance differences between platinum and iridium plugs? I don't recall reading anything on this when I was searching about the different spark plugs?

And what about the longevity of platinum and iridium plugs? I know both last longer than copper, but how do they last in relation to each other?
Negligible, and negligible. There are soooo many variables that no one can ever hope to replicate laboratory conditions for spark plug longevity tests. Just gasoline quality alone will affect spark plug life, let alone number of cold starts, number of restarts, cold drive-offs, etc, etc, etc, etc.
 

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Discussion Starter #9
ALL plugs should be properly gapped before installation.
I know this. But that wasn't my question.

Negligible, and negligible. There are soooo many variables that no one can ever hope to replicate laboratory conditions for spark plug longevity tests. Just gasoline quality alone will affect spark plug life, let alone number of cold starts, number of restarts, cold drive-offs, etc, etc, etc, etc.
Gotcha. I and I got the gist of that when reading through all of the other spark plug threads.

So let me ask then, what is the difference supposed to be between platinum and iridium plugs?
 

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Are all NGK plugs already pre-gaped for our cars, or do they have to be properly gaped?
How do you know the doofus at the parts counter didn't just drop it on the floor from the top shelf?

You should always check everything that is important before you install it, whatever 'it' is.
 

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Discussion Starter #11
How do you know the doofus at the parts counter didn't just drop it on the floor from the top shelf?

You should always check everything that is important before you install it, whatever 'it' is.
Because the 4 pack plugs are seran wrapped? That, and at least NGKs (IDK about other brands) have a cardboard protector going over the firing pin (or whatever that thing is called).
 

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The claim is that iridium electrodes can be made thinner in diameter, which would improve electron emission to create a larger arc across the gap. Iridium has a high surface hardness, density, is highly corrosion resistant, and melts at 2,500°C. Those are ideal qualities all of which are better than platinum at longevity. Yet copper requires 10% less energy to "rip" the electrons from the surface of the electrode tip---but it's lower density and hardness causes much faster erosion of the tip. But it's a lot cheaper to replace. :)
 

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The little gapping tool is dirt cheap. Check them before installation even if they are pre-gapped, it's possible they have been dropped during shipping or when pulling off the shelf. :)
 

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Other than the Bosch Platinums with the electrode level with the ceramic, I have never gotten plugs that all 8 are close to what is called for. With the precious metal electrode and ground strap ones you need to use a ground strap bending gapper tool lest you wear off that minimal amount of platinum.

I think the last set of 8 Autolite XP Iridiums I had two over .065, 4 or five around .040, only one would I put in as is. Same with the AWSF32PM (for the MarkVIII), the AGSF22FM1 (for the 97 Cougar) where all around .040 which might be closer to what most things that call for that plug use.

The Bosch Platinums seems to work well in the 89 Cougar, but not so well with the 4.6.

Coppers? If you drive more than 5-7k miles a year forget it. I bought into the Coppers for performance bit but it wasn't even 6 months per set and I got a serious drop in mileage and hard starts, and the last thing the 4 little threads per plug hole need is exercised every 6 months. I nickel threaded plug and every 4 years for me from now on. Unless I had something radical or didn't drive it much.

I would say expect 10 times the longevity from platinum versus copper, or 2 to 4 times the longevity with the nickel plated motorcrafts.
 

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Discussion Starter #16
Thanks for the info on the pre-gapping guys. I'll make sure that the pre-gap is correct and if not, I'll correct it.

I think I'll be sticking with the NGK TR55IX plugs. Kinda spendy, but seeing as they're supposed to last for about 100k miles or so, I think it'll be worth it.
 

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I've gone over 20,000 miles on a set of coppers. The gap had not changed all that much, nor were they full of deposits. I could have reused them, if I were so inclined to.
 

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Discussion Starter #18
And since we're on the topic of plugs, one last question. Is it good practice to replace the spark plug wires as well? I imagine the answer is yes, but I'm asking more for reassurance than anything :).
 

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Discussion Starter #20
Bosh brand is a good and reliable set of wires? Or are there other recommendations?
 
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