Good Morning Everyone,
Roy Dudley here. I'm getting my nerve up and planning to replace my sparkplugs and ignition wire set in my 98 Coupe. In reading other members posts, I've seen the term "index the plugs" but have no idea what that means, or if it's mandatory. Anyone have the answer?

Secondly, is there a trick to getting the boots off the plugs? I see where it's a combo of "pull, twist and turn", and I'm wondering if there's some sort of "catch" or "snap lock" issue with the plugs? Just "wiggle and pull" should do it, right?

I'm going with NTK 55 plugs and the MSD 8.5mm wire sets. Okay?

Thanks everyone...I know you'll bail me out as usual!

All the Best,

Roy Dudley

 

Indexing refers to installing plugs with the electrode in an optimum "fire" direction. That is, all pointing in the same direction. Unless you have a highly modified engine, that isnt necessary. We do it on race engines but there we are trying to wring out every ounce of hp. And yes, just a little twist and pull should do for the wires. When you reinstall, I would recommend a little electrical grease inside the boot to keep from seizing up for the next change.

 

Indexing refers to all pointing in the same direction and when refering to spark plugs and the internal combustion engine that direction is ground electrode is pointing up away from the crown of the piston as with ultra hi compression if not indexed the piston will contact the ground electrode if it happens to by chanceto have ground electrode pointing downthey sell small soft copper washers to bring the electrode into the desired position (up) no hp gains just saves plug from gettin kilt.Not needed on 99.9% of cars.Wires always break like pullin teeth ,get a tube Di-Electric grease don't be cheap on spark plug end,and wipe a little on coil end Don't take plugs out when any alum.engine is hot. For extra insurance wipe a small dab anti seize on spark plug threads have a rag ready it tends to be messy.Delco wires over the years have proven themselves again and again other wires may be as good none better and delco has the longevity to prove it. delco IRRIDUMS LAST LONGER BUT $$ OR NGK REASONABLE PRICE DON'T LAST AS LONG.ALSO MANY RESPECTABLE NAMES ON THE FORUM LUV THE NGKThewre are no "Magic" plugs that increase HP don't believe the hype about "E 3 ,Pulstar,bosche fusion to name a few

 

I remember when the splitfire sparkplugs came out.. I call them ****fires.. They would last about 5000 miles before the electrode would dissolve They were expensive plugs when they first came out

 

LOL if your spark plugs are gonna hit your piston you have serious problems my friend.The purpose of indexing a plug is so the spark faces the flame travel pattern for optimum ignition.Totally not needed on a stock or a modded street engine.

 

Some engines built to fit certain classes or engines built with ultra high compression 14 15 to one compression for whatever reason they were built ,were indeed built with the understanding the plugs would be indexed,or in lieu of indexing they sometimes would cut back the ground electrode at the spot where it would 90o over the center electrode.Yes the ground electrode would hit if not indexed or cut back NO there was not "SERIOUS PROBLEMS" .I don't know what applications would benefit from this or how wide spread this practice is in this day and age as engine design along with the amazing cylinder heads we now have with the hi swirl technology may have made this practice obsolete.At one time this was accepted practice to get that last bit of HP out of a race engine.

 

Thanks again to the Forum! I'm happy to learn "indexing" isn't part of my world...And, good advice on the di-electric and anti-seize points. Will do.

Once again, this Forum is THE BEST.

Regards,

Roy Dudley

 

cutting back the ground strap is not indexing.

 

did not say cut back ground strap was indexing stated "in lieu of indexing" or instead of indexing the ground strap was cut back.Indexing put the ground strap out of harms way cutting it down removed the part of the plug that was in harms way.In addition my friend you are erroneous in your assumption that spark plugs are indexed to propagate flame travel the ground strap in no way hinders flame travel be it wedge, hemi,":semi" hemi (big block chevy) combustion chambers.Plugs have been angled to help flame travel (old style SB chevy)Hi Perf. over the counter chevy (off road only)heads (Known as Turbo heads)were first to use this concept and was found to be just a very small part of the design as others modified their older style heads to angle plug design to find no performance improvement.

 

Never said it inhibited flame travel it merely puts the spark in the best possible position to ignite that flame front/travel.Indexing would not reduce the amount the plug protrudes into the cylinder except by the thickness of any shim(in thousands),it only changes where the open part of the plug is pointed,providing for the best possible ignition of the fuel/air mixture.What you are talking about is shimming the plug further out of the cylinder head so it doesnt contact the piston,which is a backwards way of doing things by any measure.Most tuners simply had a supply of plugs on hand and swapped them around until they found one that indexed as they wanted.

 

a
There is NO best position of spark, what is the best positon to ignite the flame front? to ignite A/F mixture?,there is no open part of a spark plug it is not shrouded by the ground strap it doesn't matter if ground strap faces open part of combustion chamber or the cylinder wall the spark is introduced the mixture ignites.where did the dialogue concerning how much the plug protrudes into the combustion chamber come from I stated indexing positions ground strap in an upward position by means of shims so the plug is screwed in not as far generally 1/2 to 3/4 of a turn will position the plug. Shims are used to position the ground strap not pull the plug out of the combustion chamber. A supply of plugs was the way it was done BEFORE shims became available the method used was to mark the porcelain to where the ground strap was: screw in, note position, remove, (if necessary) reinstall after a couple plugs you knew what thickness was needed by where the mark ended up a bunch of plugs was tedious and time consuming and not necessary as shims needed were usually 1 to 5 thous and the amount the plug was pulled out was inconsequential.

 

never did it, don't think there are any LSx shops/tuners that bother w/ this

nothing gained? I do NOT own a dyno

 

NO tuners/ shops bother with this/nothing gained you are100% right question was what is spark plug indexing it's positioning the ground strap up so it doesn't contact piston PERIOD nothing more it doesn't position the spark plug to ignite the mixture better or put a better spark no hp gain, there is no "better postion"to ignite the mixture there was an extremly small percentage of racers that needed to index plugs they were for the most part race engines with absoultely every mdification done in a quest for hp which included the most compression hence indexing plugs was necessary as all out race engines they generally made good hp guys saw this thought there was some new trick so back then many indexed plugs for no other reason other than monkey see monkey do

 

 

I would suggest you fellas try googling"sparkplug indexing" I am sure you will learn something and avoid looking so foolish in the future!You will note that in the many sites you will find,not a SINGLE one mentions a word about shimming the plug so it does not contact the piston.Nuff said!

 

indexing spark plugs on a stock engine will show some improvement providing that particular engine has an inferior head design,like the ones cited in that site,where fuel mixture is restricted to one area or by design the spark plug is somewhat shrouded and to make up for the shortcomings of the head the sparkplug is placed in a position where it ia allowed to work.In this day and age with federally mandated fuel economy (CAFE) Corp.Avg.Fuel Economy if it did ANYTHING increase power,better mileage don't you think automakers both foreign and domestic would have picked up on it??Why is it this little gem of automotive procedure has escaped everybodys scruntity? A guy with a truck, a stopwatch,on a deserted highway timing himself to the hundreth of a second is not something I would submit to the society of automotive engineers as proof positive.A lot of things are said/claimed on the internet a little common sense is needed to sift through the b.s., half truth's the common sense here is NOBODY DOES IT tuners,repair shops,Chevrolet ,Ford Mercedes,Porsche....I'm a retired mechanic,trade school graduate,45 years in the trade ,cars,trucks heavy equipt.foreign,machine shop ,welding,fabricating,crewed on professional drag race car done just about it all but in all those years i never saw in any shop manual the need to or recommend to index spark plugs for all intents and purposes the question asked the correct answer on this forum where American hi performance drag and road racing are the topics we discuss is still position the ground strap away from the piston crown.

 

When I index the plugs on my big and small block Chevy engines I mark the electrode on the open side and point that when seated toward the intake valve which is toward the intake runner of that cylinder. If you do not index and by chance the electrode faces away from the valve when it is seated it is called shouded. Indexing keeps the incoming fuel at the open spark, if turned away the electrode blocks the incoming fuel. When I raced my new 1965 GTO back in the day an older racer who was fast told me how he did it. I had some chevys in the past with bad valve quides and fouled plugs, when I indexed them they lasted much longer before fouling.

 

If you have the piston running that close to your spark plug electrode(that it will hit without backing the plug out of the head etc), You have other problems.

Indexing the spark plug is about the position of the spark. PERIOD!

 

 

Yes the piston DID run that close to the spark plug thats how horsepower was made back then there were NO aftermarket cylinder heads of any kind there were no computers to work out cam profiles we couldn't "build " an engine on a computer,no cnc,no extrude hone.all the benefits taken for granted afforded by powerful computers the internet where information is shared was not there,take away all the benefits of todays technology ,the close tolerences in machine work computer controlled cnc for exact repeatability...Cylinder heads were ground till they hit the water jackets then epoxyed or welded back up they put as much piston in the engine as would physically fit 14 sometimes 15 to one big flat tappet cams...Yes my friend I was there i saw it plugs were that close and it was never said or implied that spark plugs had to be "backed out of the head" the ground strap was merely positioned upby whatever means(washers,plug selection ect.)indexing the plugs is putting the ground strap in whatever position deemed necesary for your application however when the term is used it is generally understood to mean ground strap up for clearance of piston crown as that was the term used to describe the practice...I'm not sure what is meant by "index the plug is about position of the spark" just how does one change the position of the spark??? the spark goes from the center electrode to the ground strap. And lastly
"you have other problems",again not sure what you mean I think it's a dig or insult,rest assured I take no offense even if it is.... as I consider this a friendly ,sometimes heated debate just stating what I know as true and factual..period <(small letters)