How many of you index your spark plugs for a street car? Does it make a difference?
I have been reading up on this and since I have been messing with my spark plugs here recently, I have been thinking about doing it on my next new set. It appears that the "opening" of the plug electrode should be +/-20 degrees or so of facing towards the valves (up).
I checked one of my just to see where it was at and it appears that the opening is more like 45 degrees from facing the valves straight up. In the attached photo, the green mark on the plug represents the electrode.

I asked Moroso where the indexing washer should go and they said to remove the existing seal washer and install the indexing washer first. Then put the sealing washer on second which allows the sealing washer to do it's job.
I found this picture on the net which shows the opposite which would not seal very well.

This is a good picture showing the orientation for the plug and keeping the electrode out of the way.

Is it overkill or not?

i did it once. just once. the total aggravation of the whole process in a 69 road runner with a 440, headers and power steering for the little bit of 'seat-of-the-pants' feel just wasn't worth it.

I don't believe there is any performance gains by doing so. It's only done on motors where the piston would hit the spark plug, like on a big block chevy with hi compression.

And when I raced bb chevys I rarely used the washers, just found the right plug for the hole. You will need to start with 3 sets to get a good set. When I did use the washers I didn't remove the factory washer first, It don't matter which way you use the copper washer, it'll seal either way.

Might try cutting off the whole horizontle leg of the ground strap till your into the angled portion on the side which'll totally unshroud/expose the spark kernel to the chamber. Leave just enough angle/length so you can bend it slightly to restore the gap as it wears. Dont know if it made a significant difference but it made me feel better thinking I had done something "trick" . Keeping the edges filed sharp does reduce the required voltage to jump the gap

""When I did use the washers I didn't remove the factory washer first, It don't matter which way you use the copper washer, it'll seal either way.""

I found five kits online. I can see your point on a copper indexing washer, but Moroso leads me to believe that maybe some of the kits are not using a soft material for the indexing washers.

EDIT FROM MOROSO:
""If you have a tapered seat plug then you need to put the crush washer on
last so that it seats and seals correctly in the head. If it is a flat seat
application then the order in which the washers go on is not as important.""

Thanks for the replies.

I did it a couple times giant pain and did not see any ET gains (or losses) so bin there done that list now!

best to do it with heads off engine. get them all the same indexing positions that way with no doubt. then # the plug for install later.

i noticed a smoother idle and running engine. it will help performance. how much? results will vary.

over kill on a daily driver IMHO, on an all out high HP engine, they still do it today on the bigboys.

yes,you may need a few set to get 8 out of them.

would i do another engine? sure. if time and budget allows for it. i like tinkering with stuff like that on the bench to keep busy when building engines. in the car with headers on? i would not bother.

Don't waste your time !!

Basically following what Rapid Robert stated ,
I have seen very slight gains with a race type plug that uses a cut back electrode. With a regular plug and indexing it,I could not see a gain on my dyno with a combination I could get repeatable results on within .5 % .
As stated,sometimes you need to index a plug with a domed piston but we like to leave that to the Chebby guys with their heads with big open chambers. I would rather have a wedge design with a flat top or dish and good quench. Throw a race plug in and go.
Keith

I see what you are saying about the racing version. It appears to not care about orientation.
Is there any issues in using a race plug on a street driven car?

Thanks

I wouldn't think so IF you could get the right heat range. Just the cut back electrode would not be a problem on the street. The only thing I could think of would be not enough electrode length to maintain the gap you want as it wears down & filing the edges sharp regularly is a good plan but that'd be a long term potential problem & you'd probably replace em way before you got to that point

i honestly can not see any advantage in using those on a street car except keeping in practice with pulling, cleaning and gapping plugs. i can see it on a race car where they are tossed after a couple of runs but a street car?

I like to use Autolite race plugs in just about everything.
NGK's are good too,but most of the plugs I use I can walk in and get at the local Advance Auto. Most non race plugs have a coating on them and are next to impossible to read correctly
I ran Ar3910 plugs in my Edelbrock headed street car for years
Keith

Racing plugs for the street is a bad idea.

I see that three different thickness of washers are in the kit. What if none of the washers orient the plug correctly. Can you use two or more washers to get the correct orientation?

Since the valves are at 12:00 to the spark plug, how close do you try to clock the spark plug gaps toward the valves?
11:00-1:00? 10:00-2:00? 9:00-3:00?

Thanks

Okay,thanks. I thought maybe I was missing some other info I should know about.
Keith

There is no real reason to index(except to see what it does for your motor ) the spark plugs in most stock type SB Mopars, the plugs are almost up in the center of the combustion chamber(like a Hemi )so the ground electrode is not in danger of hitting the piston, like it can in BB and SB Chevy and Fords with dome pistons I use to do that in my 426 M.W. NHRA stocker with the high compression pistons(13.5 to1 comp. ratio). I would try to point the gap opening at the intake valve, it is a lot of work and really no measurable gains to be seen

I have never wasted my time even trying it as to me on my street car it would be a total waste of my time. I dont think I would see any performance gain and even if it did gain a half a tenth (which I dont believe it would see any gain) I am not out to set a record so why waste your time on it. Ron

I have tried indexing several types of spark plugs on a 1995 5.9L V8.

My goal was to see if Indexing would
Reduce Pinging In cylinders 7 and 8
Or
Improve idle quality
Or
Improve fuel economy.

I did not find that i could measure any lasting benefits,
but I did eventually discover that
merely loosening the sparkplugs
appears to break off carbon deposits around the plug in the combustion chamber,
which reduces pinging for a short time.

Moral of the story:
When about to compare old already installed spark plugs to new ones
always loosen the old plugs a few turns and then retighten
and go for a test drive
before installing the new plugs.

I also tried the Bosch+4 spark plugs
and after finding no advantage
tried "Indexing" this design by cutting off the ground post the ended up facing the center of the exhaust valve and leaving the other three ground posts...making them into indexed Bosch+3 so to speak. There was no performance improvement with this either,
but I did discover that the ground post that faced the hot exhaust valve did pit and wear noticeably faster than the other three ground posts.
I think this was due to the temperature of the metal when higher being "eaten away" faster when also subject to electrical sparking.
(this is kind of like Electrical Discharge Maching)

Moral of the story:
Maybe sparkplugs indexed with their ground posts away from the hot exhaust valve will hold a desired gap size longer.

This might also mean that you could gap the plugs larger to begin with,
since it is when the gap grows too large with wear
that missfires begin at high rpm and high pressures.

I originally tried indexing with copper Jacobs Ignition washers but found they allowed the plugs to get loose within a few hundred miles.

I found that if you buy 14 plugs you usually find 8 that will index "naturally"

Placing a mark down the side of your socket
and placing the spark plug into the socket lined up with the ground post next to the mark
works well and is better than
marking all the center ceramics on the plugs.

I still index plugs thinking that it might help a little.

I believe that big gaps seem to help a little too.

I believe that automakers specify gaps that are less than optimal to allow for wear that will grow them to optimal gap size.. Then eventually too big.

I believe part of the "Breaking In" effect on new engines
is growing spark plug gap size,
Along with increasing compression ratio from growing carbon deposits,
And wearing bore tolerances in hydraulic lifters becoming more Rhoads Lifter-like.

EDIT FROM MOROSO:
""If you have a tapered seat plug then you need to put the crush washer on
last so that it seats and seals correctly in the head. If it is a flat seat
application then the order in which the washers go on is not as important.""


UMMM When did tapered seat plugs start useing seating washers??

When I first started searching the web for indexing spark plugs, I only found a few "how to" articles and only a few vague threads on the process.
Now when people search the web they will find a thread with actual hands-on opinions and experience.
Thank you all for your replies!!

I wonder if the pressure graphs from two of these

http://www.optrand.com/fliers/psiplug_%20060201.pdf

Indexed 180 degrees apart
in similar cylinders
could determine if indexing
speeds up combustion.

After a first run
the two spark plugs could be swapped
and a run repeated.

Dual plug Hemis
Seem like they might offer
further test possibilities
but i cant think of how to best do that yet.

Sorry i didnt post on this topic sooner, I decided to index the plugs on my 360 magnum, i bought 20 brand new autolite 3923 plugs and tried every one untill i got one that lined up in between the 10 a clock and 2 o clock position on my engine.
I am not 100 percent sure, but i think it did help smooth out my idle even more and i think it helped with throttle response. Even if you dont feel any gains i think it is still worth it to index plugs because that way you know you are getting the best possible burn within the cylinder... thats just how i look at it. I didnt want to screw around with those washers and i wasnt too concerned about the plug being indexed perfectly... like i said i just made sure they landed in the 10 to 2 o clock position on my heads and called it good.

Lets say you had:

A Briggs Stratten overhead valve engined single cylinder 3000 watt generator that runs at a steady 3600 rpm

Two 1500 watt electric heaters to create a load

Two Kil-A-Watt true electrical power meters able to measure up to 1750 watts and accumulated kilowatt-hrs

http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU

How would you run an experiment with this generator like a mini dyno laboratory
With the single spark plug indexed different positions
To see if indexing
makes the slightest difference?

What type/brand of sparkplug?

Should the recomended gap be used
or something bigger or smaller?

Would the effect of indexing be seen more
With a tiny gap?

My first thought is to measure fuel efficiency,
but would measuring detonation resistance be better?
Faster combustion is supposed to improve detonation resistance at the same octane.

87 AKI octane gasoline
could be diluted with diesel fuel
to find a lower octane blend at which the engine would begin to ping at full load,
kinda like what they do with pure Heptane and Octane liquid blends at a State Gasoline lab with the special CFR engine.

What thinks you?

Thank you all again for your replies. It appears that indexing the plugs have a minimum (at idle) to no advantage at all on a street car.
But, I needed to regap my plugs (per MSD: existing .035" gap to .045" gap) anyway and I wanted to see what my plugs were set at currently without indexing. Once I pulled all of the plugs, I found two plugs that had the gap pointed at 5:00 and at 7:00 and the plugs showed it with darker color on the back of the ground strap. I found four plugs that were close to being correct and they were at 10:00 & 2:00. The other two plugs showed the gap at 3:00.
So I decided to go through what allot of you have already gone through and I bought the Moroso indexing kit #71910 (flat washers). It did take some time, but the weather was cold and I was listening to a game in the garage, so I had the time.
When I was done, I had all of the plug gaps facing between 10:00 and 12:00. I had one plug that I did not use the indexing washers and I left it alone since the gap was already facing 10:00. I had one plug that required two of the indexing washers (2 are ok per Moroso if req'd.) and it ended up between 11:00 & 12:00. All of the rest fell into the 10/12 range with one washer each.
I have no expectations but now I know that my plug gap is correct per MSD and that my plugs are all in the best orientation (between 10:00 & 2:00) that I could achieve.

Thank you again for your replies.