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spark plug question

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Posted by: 98LSC32V

I'm about to change the plugs again on my 98 LSC, should I use 1 step colder or go back to stock heat range? Mods in sig...

Posted by: LINCBRA

Plan on running N02?

Posted by: 98LSC32V

No, that's why i'm probably gonna go back to stock heat range. Some people say though with a chip it's better to run 1 step colder because the timing is advanced so i'm not sure.

Posted by: 1wykdmk8

I have been running the Lightning plugs in all my Mark VIII's for years now. I have never had a problem with them whether the car was bone stock, or chipped. They are 2 steps colder actually, and you can get them from Max @ 5 Star Ford.

Posted by: ONEBADMK8

I use Autolite Copper #764's gapped @ .048.

Posted by: mespock

Same here...

Posted by: driller

Run the coldest plug you can without fouling for the best knock protection. The Mark VIII knock sensors will pull timing long before it's audible. Max performance is with the most timing advance - all other things considered equal.

Examine the plugs and look for black carbon-like material buildup in the insulator area. If the insulators are clean and look to be burning normally(light tan/gray with no spots), you may even try 2 steps colder.

Spark Plugs 101

Posted by: turborich

Just use the factory recomended plug! It's in there for a reason. The platinum motorcraft plugs that came with these cars lasted for at least 100,000 miles. Why not just use what is recomended? Why use a copper plug when it needs to be changed every 12-15 K ? With all the talk about the 32 valve plug threads striping out, why would you even take a chance?

Posted by: driller

Quote:

Originally Posted by turborich

The platinum motorcraft plugs that came with these cars lasted for at least 100,000 miles. Why not just use what is recomended?

You trade longevity for peak performance.

Posted by: 93' Blue on blue

Is this a problem on our cars? I thought as long as the engine was cold and the plugs only done up to recommended torque all would be well. Surely a plug thats been sat in a head for 10 years plus with 100k on it could pose problems in itself? Just a thought...

Posted by: 93' Blue on blue

Im using the autolite 764 gapped at .054''. According to some sources, the bigger the gap u can get away with without misfire, the better. (N/A)

Posted by: turborich

Quote:

Originally Posted by 93' Blue on blue

Is this a problem on our cars? I thought as long as the engine was cold and the plugs only done up to recommended torque all would be well. Surely a plug thats been sat in a head for 10 years plus with 100k on it could pose problems in itself? Just a thought...

I have not had this issue, However several others on the board have. There is quite a bit of talk of thread issues. The same thing happened on my friends 03 Supercharged Harley, Cruising down the road and a plug just popped right out of the hole and took the threads with it! I don't know why this happened but it cost him a new set of heads!!!

Anyways, I honestly think that factory plugs are best. Maybe a 764 copper plug if you like changing them

But why all of the lower heat ranges if there are no issues with the engine? That heat range is there for a reason.

Posted by: 02LSE96LSC91SE84TC

Usually overtightning is to blame. However my car had 67k when I bought it and had stock plugs in it. They were so tight to remove I had to use a 1/2ratchet...tight all the way out. Either the stockers were just jambed from being old or replaced and overtightened stock units were put in at some time. After completing the change I knew it was just a matter of time or next replacement that threads would be gone. It shot out one will driving. You don't have to replace the head or even pull it. You can install thread-serts.

Posted by: turborich

Quote:

Originally Posted by 02LSE96LSC91SE84TC

Usually overtightning is to blame. However my car had 67k when I bought it and had stock plugs in it. They were so tight to remove I had to use a 1/2ratchet...tight all the way out. Either the stockers were just jambed from being old or replaced and overtightened stock units were put in at some time. After completing the change I knew it was just a matter of time or next replacement that threads would be gone. It shot out one will driving. You don't have to replace the head or even pull it. You can install thread-serts.

On my friends, he somehow dropped the end of the re threading tool into the cylinder so he had to pull the heads, He took them to a machine shop that ended up re threading them too deep into the head. That's why he needed to get another set of heads.

Even so, why take a chance?

Posted by: 93' Blue on blue

Damn! i hope i dont have this issue anytime soon! lol. Trouble with a thread insert though is heat dissipation. That particular plug will react differently to the others. (get hotter) Not to mention the possibility of metal fragments in the cylinder. Why cant Ford design things right in the first place? They have had over 100 years practice! Lol.

Posted by: Brozly

Aluminum can be some nasty stuff, stainless isn't much better...

Posted by: 93' Blue on blue

Titanium is a nice metal. Shame its so expensive!

Posted by: 02LSE96LSC91SE84TC

Quote:

Originally Posted by turborich

The tool I used was designed for it, there wasn't a way to drop the tool in from what I remember. Sounds like a poor machine shop. I did all eight to never have the problem again and they are all the same. I can't imagine comparing the $120-$130 I spent for eight thread-serts to his bill.

Taking a chance on what?

Posted by: turborich

Quote:

Originally Posted by 02LSE96LSC91SE84TC

I meant taking a chance on using the copper plugs, having to change them out every year or so. The aluminum threads may become weak. That's what I meant. There is nothing wrong with re threading them if they are done right. The machine shop must have sucked! I agree.

Posted by: 02LSE96LSC91SE84TC

Quote:

Originally Posted by turborich

Oh I see. Yeah my problem came with the car, not that I new. I did the plugs a few thousand after getting it and was really amazed how jambed they were. When it spit out some 15-20k later I wasn't really surprized.

Posted by: 93' Blue on blue

What is the correct torque for our plugs? ive been searching and getting all different specs between 7 and 16 ft/lbs. Also, just been doin some reading on modular fords.com and there seems to be an issue with the early mod heads not having enough threads? 4 threads or something? Ford got legal action took against them by NHTSA? Can anyone shed any light on this?

Posted by: 02LSE96LSC91SE84TC

Quote:

Originally Posted by 93' Blue on blue

What is the correct torque for our plugs? ive been searching and getting all different specs between 7 and 16 ft/lbs. Also, just been doin some reading on modular fords.com and there seems to be an issue with the early mod heads not having enough threads? 4 threads or something? Ford got legal action took against them by NHTSA? Can anyone shed any light on this?

The Torque Spec is low but I'm not sure exactly. 4 threads is about right. Can't say about the rest.

Posted by: chickenviii

10-20 Nm/84-180 In/lbs

Posted by: 93' Blue on blue

Cool! Thanks guys! Now im gonna start tightening them correctly rather than the hand tight + qt turn guess! lol.

Posted by: turborich

Some of the SC harley trucks & lightnings have the 4 thread holes as well.

Posted by: SpdMongrel

How much performance gains are there in changing to the autolite plugs? Im still running factory type.

Posted by: driller

Quote:

Originally Posted by SpdMongrel

How much performance gains are there in changing to the autolite plugs? Im still running factory type.

I for one do not believe you "gain" performance from spark plugs, rather you allow the engine to make the most of what it has. Most gains from ignition parts are only regaining HP what has been slowly lost from age and use.

Having said that, certain plugs will allow more HP to be gained from timing advancement via a chip or tune.

Posted by: SpdMongrel

Ok thanks for the quick response.

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