Help spark plug indexing
 

So I'm somewhat stuck. Everytime I use my snap on trq wrench set at 23nm, my plug is not indexed right. What gives? If I try 34nm it ends up being in the needed 45* angle. I'm using the bosch plugs that fcp sells. But if I use the trq wrench and set it to 45* it ends up being indexed correctly, but is then overtorqued. What am I doing wrong?

nothing. I always order 10 plugs for this reason...

wait, you know there is only 90° of "bad" and 270° of "good", right?

So are the plugs not reusable if they have been over torqued?

not necessarily, you're just squishing the copper gasket the more you torque it. I guess, if you were to overtorque, release and retorque to the proper torque and it's in the correct window, use it

basically, the strap can be anywhere from 1:30 to 10:30 (in respect to the 'hour' hand) since the injector is at 12 o-clock. you need to leave the 90° from 10:30 to 1:30 clear of the grounding strap so as not to interfere with the flame front propagation.

someone was buying different copper washers and indexing their plugs, but that seems a little extreme to me

If I tighten at 23nm it is between those area(clock hour hand). For example i did cyclinder 1,torqeued at 23nm the plug was facing the front of the car towards the bumper. Is that right?

If by "plug" you mean the grounding strap, then yes, that's fine.

No, ground strap is facing the rear of the car, the open part faces the front of the car, while the injector is to the right of it at 3 o clock

that is fine, you just don't want the strap between the tip of the plug and the injector.

just for reference, let's make sure we're on the same page. let's look at it this way:
When you look at the plug, look at it from the side of the engine so that is is extending out in front of you, horizontal to the ground with the strap facing away from you. Now, think of the circular shape of the plug as a clock face. Your strap is facing the rear of the car and open to the front of the car, so lets call the strap 3 o-clock. The injector is directly above the plug at 12 o-clock. so, like I said before, thinking of the plug, your strap(3 o-clock on the example) is okay to be anywhere within the 1:30-10:30 area, so it does not block the spark from reaching the fuel being sprayed by the injector. Does that make more sense?

Here's a few other resources about indexing plugs on the M157... as nota_amg said and many others have, you will probably want to buy several extra plugs as there are very minor differences in the plug thread position which can impact the indexing even if you follow the spec and torque to 23nm.... my buddy is a MB master tech and he's stated this is definitely a tricky process but if you order extra plugs you should get enough of the ones that line up properly.

https://mbworld.org/forums/attachmen...g-indexing.pdf
https://mbworld.org/forums/w212-amg/...ark-plugs.html

I looked at all that. Maybe I'm just over thinking this and trying to get everything in spec VS just put the plug in, torqueing to 23nm and call it a day

You're over thinking it. Install MB spark plugs at MB specified torque. That's all.

Are these not MB spec plugs?
https://cimg6.ibsrv.net/gimg/www.mbw...58524de753.jpg

I don't know. Buy them from MB of Naperville. They have an online parts ordering, carry good inventory and have fast standard shipping. I just ordered rear brake parts from them and it was a good experience and fair prices. My local dealer price for the brake parts was 50% higher than Naperville.

If you use anything other than MB spark plugs, you will chase your tail endlessly on the torque vs angle/position. With MB plugs, they are made to be installed with the correct torque, and the acceptable position is the result. In other words, follow the instructions.

Yea I think il just do that. 158 with tax for a set of 8.dont think I can go wrong with oem. Do I still need to gap them or these are good to go?

Ok figured it out. Stupid torque wrench wasn't calibrated right and it was set to 23ftlbs instead of 23nm. Re-did everything over again and everything is within spec

Don't gap spark plugs. Forget anything you may have learned from working on 1980 Chevys and Fords. I had to do this myself.

nevermind...

What does this suppose to mean 😅

That is wrong, and dangerous. You obviously have no idea what the M157 needs or requires to run properly. Spark plug gap is CRITICAL in the M157/M278, especially if they are tuned.

Tuning has no relevance for me. MB specs as documented are relevant to me. If an owner tunes, caveat emptor.

These are OEM plugs from FCP for 2016 E63 AMG s -- I checked at the dealer once I got them.. so the kit you have has these and they're good.
The advantage with FCP.. you use these for 10-20K miles with your tune. Take them out - send them back and they send you another set for free.. :)

Description

Details

• SKU: BOS-0242140521
• FCP Euro ID: 516992
• Made in Iridium
• Quality: OE

All of them torqued at 23Nm ended up with open face at like 10:40 PM so I overtorqued by 0.4 Nm to end up at 11:30 - yes OCD ..

I may be misunderstanding you here, but there is 90 degrees of acceptable plug angle, with the open face of the plug towards the injector. Your statement seems like the bad and the good are backwards.

I think what he is saying the STRAP Can't be in the 90% in front of the injector...
I think this also means that that the open face can be outside of the 10:30 and 1:30 as long as the strap isn't in that 90 giving you 270 of "good"..

From what I UNDERSTAND from the bulletin the OPEN face should be in the 90% 10:30 - 1:30 for proper indexing-- giving you 90% of good as @5soko highlights.. but what do I know..

Torque spec is your friend. Too much overthinking on this thread. Buy MB parts and install them according to MB specs.

yes, i agree with this, this is what i understand aswell.

https://cimg9.ibsrv.net/gimg/www.mbw...661632ffa2.png

you are correct, I stated it backwards.

You had me second guessing myself for a second lol

Just using Merc plugs and torquing to spec totally did not work in my M278 engine.

Bought 3 sets of plugs. 9 Mercedes branded plugs from FCP Euro, a few of the same Mercedes labeled plugs from my local dealer, and 9 of the same part number with Bosch labeling.

ALL OF THEM indexed wrong. ALL were aiming at about 7 o'clock. (well,.. I only tested 2-3 from each set) Whereas they need to aim between 10 and 2. (The open end of the ground electrode)

You CANNOT just put them in and trust they're right,.. and you also should never trust this job to a dealer or an indy. I asked 2 indy's as well as the tech at the dealer about indexing plugs,.. and all had a puzzled look on their faces. I don't think any of them had any idea what I was talking about. The one tech said they use Merc plugs and just torque to spec. And admitted he had never checked to see if that produced a correct result.

It MAY in your engine,.. but it didn't in any cylinder in my 2012 car.

Now,.. the original plugs DID. And I hear from Eurochgarged, FCP Euro and others that after '12 they realized the plugs were a tad hot,.. and the plugs used thereafter were a bit cooler.

Did the heads change for 13? Did the threads on the plugs change when they made them cooler? I don't know the answer,...

threads are still the same. I use the colder plugs(NGK-97506) and they are close...but I always order extras, just to be safe. I have a record of 4:5 being correct.

Yeap - Indexing is important and while I understand people that say stock this and stock that I really APPRECIATE YOU but this conversation is for those who want to push the limits and figure out how to do it in the best manner possible.

Conclusion in my mind is - stick to spec but verify -- now that I understand the indexing fully I'll try going back to NGKs because I feel I had better performance with those bad boys when I didn't have misfires (Which I think I finally resolved)..

Great thread, great info.. Thank you all.

Agreed, this is very informative. Thanks TECHNICIAN, nota_amg, and Duckstu :y

Plugs
 

Anyone know the difference between the ngk 1555 and the 97506? Ngk says the 1555 protrudes about 2.7mm more than the 97506

I'm back hahaha. Installing step colder plugs as I'm going s2 next week, and so far 3 plugs I tried will not index properly. Will try my 4th and if that doesn't work I will reinstall the oem ones gapped at 0.022

I just did a 2014 E550 and the Merc plugs that were in there (at 55,000 miles) were all over the place,. AND NONE OF THEM were aiming within 45 degrees of the injector. Most aiming down at 7 O'clock.

The new Merc plugs I bought from FCP Euro, as well as the ones I bought from my local dealer were also aimed down. Totally acceptable.

Same with the Bosch version of the same plug.

Yes 23 nm is the torque spec,.. but installing factory plugs and properly torquing them WILL NOT cause them to be installed correctly.


This is NOT a job anyone should ever let a dealer or an indy attempt. There is about zero chance they will do it correctly.

I bought 4 sets of copper washers off Amazon trying to get washers that were 12mm ID x 16mm OD and 1mm thick (12 x 16 x 1). Only one set were actually 1 mm hick. The others were 0.7 or 1.5.

With that set I was able to get 4 or 5 of them to be within spec.

I sanded down a Bosh 1.5mm wsher to get the rear-most cyl on the driver's side close,.. and the front 3 on that side are almost withing spec using 1mm washers.

On the notepad below I recorded the before and after (before being the arrows inside the circles,.. and after being the arrows on the exterior of the circles).

. The 1mm washers corrected the pass side bank nicely,.. but only managed a slight improvement in the left bank. The rear most cyl I sanded down,.. but really needed to do all 4 like that,... or find some 1.3 mm thick 12 x 16 washers. Need to buy 3-4 more sets I guess and keep measuring.


https://cimg8.ibsrv.net/gimg/www.mbw...225c29f9cf.jpg
.

Here's the washer sets i have. The ones in the set with the red arrow are the only 1 mm ones I have found so far.

https://cimg2.ibsrv.net/gimg/www.mbw...bb84edb47b.jpg

I just reinstalled the oem plugs, gapped them to 0.022 and torqued to 23nm and all of them facing towards the injector.

With the Ngk step colder, best I could get is 6, meaning the back of the plug was facing the injector, so I gave up after trying about 4 diffrent plugs

I spent an hour or two the other night sanding down stock plug washers from 1.5 mm to 1.2 to 1.32 mm and then re-index'd the driver's side bank. Got them all well within spec.

Arrows INSIDE the circles were how we got the car, presumably with orig plugs.

Black arrows outside the circle were after we changed them, and used 1.0mm washers on 7.

The red arrows are my 1.2 - 1.32mm washers.

Looks like 1 mm gives almost a full rotation. Perhaps 340 degrees.

Going from 1.5mm to 1mm allowed the plug to index clockwise almost 1/2 turn.

Hopefully that will help everyone know what thickness washers they need to custom make.

https://cimg5.ibsrv.net/gimg/www.mbw...c1b76acf20.jpg

So adding a 1mm washer made all the Difference?

NO,

REPLACING the 1.5mm washer that comes on the plugs with one that is 1.0 or 1.2, or 1.3 is what did it.

The problem is,.. it's very hard to find a 1.0mm thick 12 mm x 16 mm copper washer, (The one set I pictured above had them, the others lied) .. and it's impossible (so far as I know) to find 1.2 or 1.3 mm copper washers.

So you have to make them.

Ah i see 👍

I just re-did the plugs in my 2012 E550.

Previously I had found that both factory and the Bosh branded plugs index'd at about 7 -o'clock,... so I closed the gaps a bit, sanded the tips clean, and re-installed them.

Last night I installed a new set, and found that they all wanted washers in the 1.15mm - 1.2 mm range. (Stock washers are 1.5 mm)

And sanding down the stock washers presents a bit of an issue, where the washers no longer have a curved surface where they meet the head. And with a now wider and flatter mating surface, they won't crush as much. I.E. they wont continue to rotate as much when you torque them to spec.

So I beveled the inside edge a bit with a Dremmel, and beveled the outside edge with a belt sander,.. so that the mating surface would be narrower, and I could still get a good crush.

A lot of hassle.

Arrows on the inside of the circles are where the original plugs from late 2011 were (on my M278 2012 model year engine).

Arrows on the outside of the circles are where I ended up, and the washer thickness I used to get there. Thinner makes it move clock-wise, thicker moves the ground electrode counter-clockwise.


https://cimg5.ibsrv.net/gimg/www.mbw...4269a7d365.jpg

Has anyone noticed a difference in the way the car runs after indexing? As described this is quite a bit of work for what may be intangible gain. I like the idea, it has been done for decades, but is is worth the effort.

Well it's something the amg engineers said needs to be done and guess makes sense. Then again, bunch of direct Injection cars on the market that don't need indexing that run fine, including bunch of competitors like the m5

That might be quite a project.

Any differences most of us notice are more likely from the plugs being new..

Someone would have to put their car on a dyno with new indexed plugs, run it, then, while still strapped to the dyno, swap in similar new plugs, poorly indexed, and perfectly match the operating temps and run it again to find out.

The dire warning in the things from MB is about how it's critical to have the correct temp plugs and have them correctly indexed,.. or else (with pic of burned piston).

Who's to say how much of that damage was from incorrect heat range, and how much if any from the indexing.

I looked at some of my piston tops with a bore-scope while I had them out, and they all just looked a bit sooty. Less so on the '14.


For sure back in the day we'd get power out of our 2-strokes by indexing plugs. Perhaps it's worth 8 hp?

Translation: "If an owner tunes, let the buyer beware." LOL

Si latine uteris, recte fac:

If an owner tunes, est ludus eorum.

My "grammar nazi" lesson for the day. :o:

So much effort and as pointed out above, nearly no one knows how to do this properly. Has anyone seen any failures or damage from not correctly indexing plugs?

In a tuned engine, with upgraded turbos, internals, WMI, etc., such as I'm currently doing on mine (Weistec W.4, complete) there are factors introduced which make indexing much more critical than in a stock motor.

1) EXCESS HEAT. This requires using one step cooler plugs to avoid high risk of detonation, which can be catastrophic.

2) TONS MORE FUEL. It's required in order to produce up to 1050 horsepower, so in order to burn it all efficiently, without fouling the plugs, they MUST be indexed.

There are lots more factors introduced with major mods, but there's no need to write a book here. I was just indexing my plugs on Friday, using NGK Iridiums with the heads off it's super easy. However, no washers needed to be changed. At 23Nm they all fell in the perfect range.


https://cimg2.ibsrv.net/gimg/www.mbw...98f24daee5.png
NGK Iridium 1X Torqued to 23Nm. Supplied washer.
https://cimg3.ibsrv.net/gimg/www.mbw...e029a93925.png
NGK Iridium 1X Torqued to 23Nm. Supplied washer.

@TECHNICIAN hey sorry to bubble up this old thread on plug indexing but wanted to ask if you could confirm something based on the MB photos of the proper indexing here where the open side of the electrode must face the injector per MB.

***Based on the MB photo above - is the injector (not visible in the photo) located ABOVE the spark plug hence the plug electrode open end is correctly pointing up around the 12 o'clock position if looking at this from the side/fender? My apologies for being confused but I really appreciate your feedback here. Thx JV

Yup. BUT, the injector is staring you in the face. That little dark nipple that the open end electrode is sorta pointing at. Also, intake valves are up/inboard. Exhaust valves are down/outboard. UNLESS you have a 4.0, then everything's upside down.

thanks @S63C4 I feel like a dummy as I assumed dark circle/nipple in the photo was injector but was confused... Mine is a w212 / M157 (not 147!!!!) would be as you stated intake values up/inboard and exhaust values down/outboard.

found this video from MB explaining the M157 engine ( ) and at the 2:45 min mark shows some very clear animation of the injector/plug position .

thanks again and apologies for the novice question :)

You need some sleep. Your E63 has an M157, so I'm hoping that M147 is just a typo, or else you have Essen wheels on the brain.

BTW, I ended up pulling the Iridium plugs after the heads were torqued onto the block because I opted to go with Ruthenium plugs instead. The ones I used (LKAR8BHX) are supplied with soft crush washers installed instead of hard copper. Every time I reached 23nm, I yelled out, "GOD, I LOVE CRUSH WASHERS!!" Every single plug was indexed at 12 o'clock on the dot! SO DAMN EASY to adjust torque/index! I used one indexing washer because one plug just wouldn't hit 12 exactly and I'd run out of crush. The Rutheniums have been absolute beasts for 800 miles and yeah, I've pushed it early, but it's fine. With 1050 HP and 1010 lb ft of torque and WMI with a BOV and the MCT 7 full of racing clutches, I challenge anyone to break it in gently the entire 1000 miles! Damn, this car is SO MUCH FUN! I only wish it did what Weistec advertised, but 2.7 seconds 0-60 is an outright lie. It's impossible.

BTW... Seen that vid over a year ago, but ty.;)

Ha yes @S63C4 i do need some sleep and should wear my glasses when I'm typing!!! Appreciate the heads up on the NGK Ruthenium plugs (https://www.ngk.com/ngk-91784-lkar8b...henium-hx-plug) and awesome to hear they correctly index with the MB spec torque of 23nm. I would also YELL out like you my love for crush washers if these suckers index that easily and correctly since guys like us with tuned M157 motors gotta be changing the plugs every 5k-10k miles and its a PITA job! Your S63 is a monster congrats cannot imagine what that power must feel like! Not many tire set ups out there which can handle that much power on a car like yours!!!!

Super appreciate your feedback I may buy a set of those NGK Ruthenium plugs and give them a shot as my 15 E63S has a AMS tune on 100 octane with BB intakes. It dyno'd 746 whp and had zero misfires until the last couple months but the current NGK plugs are at 12k miles (total miles 49k) and waaaay overdue for change!

Proper indexing is one thing, but changing plugs that are made to run 100,000 miles at 10-15k is just a silly waste of time and money. Until I see a sign, repeated more than once that the plugs may be misbehaving, I'm not touching them.

As I said, my car is NO FASTER off the line than it was before the Weistec infusion. The torque limiting cannot be reduced enough to get the 4 wheels to break loose, so I could be running bias ply Korean sneakers on it and never smoke 'em up. @ 24 mph, you get SUCKED into the seat, HARD, but 0-24 is granny drive time and there's NOTHING you can do about it, believe me.

Your 212 is RWD, I'm pretty sure, so you don't have the forced limiting that 4MATIC demands. I only wish I could convert to RWD and have some REAL fun, like you do. I bet you'd beat my 0-60 @ 3.8.

@jvakos has a 0-60 with 60ft of 2.8 ...he's got a 2015 4matic e63 as he mentioned; I have same intakes and dyno tune and have same dragy performance data... tcu tuned by edok

https://cimg2.ibsrv.net/gimg/www.mbw...7f2329d6d.jpeg

SWEET! I'm jealous as hell because an S class can't be tuned to do that. WTF!?! Even Weistec said, "The S63's a boat! If you wanted 0-60 times you shouldn't have gone with large turbos made for top end speed, you should've bought an E63." Ya, like there's even a comparison!! P-LEEEAASE.

Race start doesn't help?

It's an S63, not a CLS63.

Oh I didn't know they didn't put that into an S platform vehicles.

@Duckstu - thanks for sharing your findings here on the OEM plugs and indexing issues... Am having the same issue where the FCP purchased MB OEM #A004-159-81-03 plugs will not index within the acceptable MB range (45 degrees either side of the injector - or 12 o'clock position. So far I tested 6 different plugs on both cylinder 1 and 2 and none will index beyond the 9 o'clock position with the open face of the plug.

These plugs came in a little MB box with a damn MB star printed on it and the FCP site says they're guaranteed to fit. Also called my dealer they said these are the correct OEM MB plugs that should index property.

Product Information (https://www.fcpeuro.com/products/mer...des-0041598103)

This Genuine Mercedes spark plug specifically designed for the Mercedes M276, M278, M157, M152 direct injected engines and it's variants.
The threads in the spark plug and in the cylinder head are calibrated in such a way during the production that the correct installation position is guaranteed

• The spark plug has a copper sealing ring that maintains a defined and small clearance even after repeatedly correct assembly measures
  
• Proper installation torque must be used 23Nm

I was considering trying different washers (per the above) but didnt want to damage the plug threads trying to wrestle the washer off so am giving up on these MB OEM plugs.
I just ordered the NGK 1555's which my indy previously installed and every one was indexed perfectly at the 12'oclock position so will report back on how that goes.

Am simply trying to follow the MB recommendation here and perhaps the index facing 9 o'clock is not that big of an issue, but being tuned I dont want to take any chances.

Appreciate all the sharing on this "indexing" topic that is giving some of us DIY folks headaches

There was someone in a previous post(possibly this thread) that stated that it’s almost impossible to get the proper indexing because none of the components that affect it(plug and head) are perfect. And they said it’s ok, they haven’t noticed any performance loss. If there is, it’s probably a few HP at the most.

Its not the power loss concerns from a incorrectly indexed plug, my biggest worry is about the potential for piston or cylinder damage as MB states “could happen” if outside the acceptable range. May just leave them as is (close to 9 o’clock position) and closely monitor to see if any misfires or issues and call it a day.

I’d be curious if they were indexed correctly out of the factory in our cars and by MB dealership mechanics whenever changing them for E63 owners - have actually correctly indexed them during that service.

The fact that the correct plugs don't index properly at the 23 nm tells me there is more to this than what Mercedes are claiming via bulletin. That, or there's actually less to this...

Seems more like a bulletin to get out of warranty work. Problem is, we can't afford to ignore the information given how sensitive these M157s are.

I have talked to multiple mb techs(my cousin works for mb in Germany) indys techs and each one says that the trq spec is what they all look after. The indexing part is something that no tech looks after as it's next to impossible for all 8 plugs to be indexed right(especially when Mercedes says "when torqued correctly they will always face the right way).

I to have tried multiple torque wrenches to achieve this thinking the issue was my snap on torque wrench, after a few tries I just started to get frustrating at the end of the day. Had 10 Bosch plugs not face the right way, does this mean the whole box of plugs is a waste now??

I'll get my NGK1555 plugs tomorrow and hopefully will report back positive results on my 2nd attempt at correctly indexing since the MB OEM Bosch plug didnt work out :)

Out of curiosity I may go ahead and order a few single OEM spec'd plugs from the different manufacturers to see which index propertly...

MB makes it sounds like its magic or something to correctly index M157 plugs, but net net if the threads dont line up then no matter how close to 23NM you torque it the plug will never line up unless you grossly over / under torque them.

I have been assuming that slight deviations in the torque could at least get within that 90 degree range. If people are saying the torque often yields about 45 degrees off center (the limit) then I think my statement is probably correct.

I've personally tried with my heads off to tq to spec and index plugs and it's absolutely impossible to have them all perfect . There's no way anyone should waste time trying. I've never seen an engine fail from not indexing. For me it's an excuse for them not to warranty. Stock plugs tq to spec don't index. So the bulletin is pointless . I ran Hks plugs gapped to .26 facing the opposite wAy and stock factory plugs for over 40k miles on an aggressive tune, and never had an issue . I think personally everyone is over thinking this. Just get plugs gap them correctly and call it a day. What's actually plays the biggest role is plug gap. The biggest you can put that won't get spark blow out from incoming boost .it's well documented that the biggest gap you can run in your setup will net the best performance. Everyone runs .22 because it's seems to be the go to number that was passed down from previous venders that ran plugs that were colder. I as well did .22 put just didn't like how my engine responded. Idle was a bit funky, slight missfires, I noticed the plug would look as if it was over heated. So I went up to .25 and right away the idle felt smoother, car didn't have mysterious misfires, and when it was time to service plugs I didn't get the same signs of a plug that looked over heated. They looked great!, so I decided let me
bump up to .30 just for a test to see if I will get any misfires or any negative effects going to a much bigger gap opposite of what's been the so called go to gap. Well the car ran great again, no misfires no hesitation. The ran perfect. I did multiple 60-130's ran multiple 10.3 quarter mile runs back to back and while running a **** ton of methanol. So to date my plug gap is and will remain .26 not to big not to small , just right. If anyone is running .22 and your having bad idle issues or unexplained misfires you can't find. That gap may be your problem. Again I know what's good for me may not be good for others but im just giving you guys my opinion from what I've done. I definitely don't expect everyone to agree with me but I suggest you give it a try or perhaps do some research on your free time and look up plug gaps indexing etc. I'm not saying indexing doesn't have merit or pros, but for this engine I don't see it.

This is exactly the post I’ve been waiting for. For me, I’m just going torque to spec and call it a day. I believe mine are running factory gap as is. Once the time comes for me to replace these plugs, I’ll try a more conservative gap like yours.

Currently running factory gapped plugs on my car and have had no issues for the last 25k miles with plenty of hard runs and pulls. I torque mine all to spec and fortunately for me, they all indexed pretty close to what's shown in the diagrams presented here.

Tuned?

said I would report back on my install of the NGK 1555 plugs….finished them last night and am VERY pleased to report they all indexed within spec with 23NM of torque. All we’re positioned either just to slight left or right of the 12’oclock position (electrode open end facing up towards injector).

The OEM Mercedes Bosch plugs that I attempted to install on all eight cylinders faced either 9’oclock or 3o’oclock at 23NM torque (digital torque wrench used). That is still pretty close and likely fine but technically still outside the MB spec per the documentation.

I bought the NGK 155 Plugs from Rock auto for $14 bucks a plug as well which was the cheapest of any website for those. They were the plugs that my Indie guy installed just prior and lasted 12,000 miles on a 100 Octane race fuel tune and had zero misfires until the past couple months since the plugs were pretty black especially cylinders 1 and 5.

Im an amateur with wrenching on my M157 but happy to share any feedback on the process for those who attempt this. Not required, but I would definitely recommend buying that Hazet plug socket on amazing for $55 bucks it is the perfect depth for the cylinder and the swivel goes to full 90 degrees to help you easily get it into the far plugs 4 and 8 by the firewall.

Yup, stage 1 tuned from ECC.

So, ladies and gents, final verdict ? Just gap and torque right and that's it or is the indexing a real factor or insignificant(as long as oem plugs are used)

there is no data to convincingly prove one way or another, here's what I've done and keep doing:

- OEM plugs gapped stock (on all my tune files)
:: 93, 100, e40, stock ::
- torqued to 23nm without excessive concern for indexed to perfection
- replace coils and plugs every 5k miles
- drive and enjoy this amazing toy

Whoa... this opened another can, replace coils and plugs every 5k ??? That's a significant expense ! Now, for the stocks out there and mostly stage one guys, I've read here that 10k miles plugs only is sufficient. Does stage one really chew through plugs aaannd coils that quick ? or this is just for prevention and peace of mind ?

peace of mind - the significance of the expense is up to the owner, for me it's a non issue. All it can take it one bad misfire and I'm hedging my bets. Here's the best part, to each their own.