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Baller04B
Dodge Dakota
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7/03/2006
21:51:48
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 Subject: Plug Indexing
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I have a 2003 3.9 SXT and I have a few questions about spark plug indexing. Before I get into the specific questions just generally speaking what does everyone think. Pros, Cons, waste of time, etc.
More specifically if I decide to do this for performance or just because I like to tinker with my truck.
1. I want to locate the gap generally between 10 and 2, correct?
2. Does brand of washer matter? I saw that Moroso was the cheapest most places. Which size group of washer would I want - Group 1 = .043, .050, and .064 Group 2 - .010, .021, and .032
3. Is the correct application of the washers to remove the existing spark plug washer and add the new indexers or to just add on top of the existing?
4. Is it okay to notch the electrical terminal so I can feel where the gap is on my plug since I can not see a mark on the side of the plug?
Any help and knowledge will be appreciated. Thanks in advance.
Brian
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shatto
Dodge Dakota
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7/04/2006
02:42:31
|  RE: Plug Indexing
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Look around for an old Jacobs manual. Dr. Jacobs went into great detail on the subject, as well as far more than you'll ever need about ignition in general.
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zzark
*GenII*
7/04/2006
09:27:02
| RE: Plug Indexing
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gap between 11 and 1
buy a set of all sizes
some plugs you can't remove washer
Why can't you SEE a mark on the plug?
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Baller04B
Dodge Dakota
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7/05/2006
07:24:17
| RE: Plug Indexing
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Thanks for the information.
Shatto I will definitly check out a Jacobs Manual and see what I can learn.
zzark if I were to put a mark on the side of the plug with a marker or something when I went to install the plugs I don't think that I would be able to see the mark do to what I believe is just a heat shield around the plug. I may be wrong, I don't know. I am new to this truck and working on vehicles period. When I installed my new plugs a couple months ago that is what I thought but I was not looking because I had not considering indexing yet.
Anyone else have any Pros or Cons to indexing your plugs?
Brian
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daddio
Dodge Dakota
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7/05/2006
08:44:51
| RE: Plug Indexing
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you can get rid of the heat sheilds if you want. when you put the plug in the socket make a mark on the socket and up an extension then you'll be able to see where your gap is. that's how i did it.
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zzark
*GenII*
7/05/2006
10:40:11
| RE: Plug Indexing
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Ok, you are correct. I forgot about the heat shields.
Remove the damn things. You'll be glad you did.
Just grap with a visegrip and twist n' shout.
Make sure you use compressed air or a water hose to clean around the plugs after you remove the shields.
They usually hold alot of gunk.
zzark
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N56629
Dodge Dakota
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7/05/2006
15:35:08
| RE: Plug Indexing
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I don't know if indexing is worth while but here's something to think about. How much does this change the volume of each chamber? I don't recall what the thread pitch is on a spark plug but I think it is on the order of 16 threads per inch. this means that there could be a difference of almost 1/16 of an inch difference in depth from one plug to the next. I guess I'm wonder if this would negate any advantage in indexing the plugs.
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bludak
Dodge Dakota
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7/05/2006
16:40:32
| RE: Plug Indexing
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The amount of performance that you will see out of indexing is not even noticeable in the 3.9. I would say that it will not yield any real results that you can feel or hear. I would not bother. I did the indexing on my 72 340 Dart with Nitrous and it made no difference in the 1/4 mile times.
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Baller04B
Dodge Dakota
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7/05/2006
19:07:04
| RE: Plug Indexing
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It may not help but does it hurt? Like N56629 was saying does changing the volume of the chamber have any neg. effects and are they noticable.
Sorry if I am asking dumb questions but like I said I am new to working on vehicles but I enjoy it and even if it is "worthless" I may still do it because the more I am messing with the engine the more I am learning. I just don't want to do anything that will have bad effects.
If I am to do this I saw that there are tapered seat washers and flat seat washers is one better then the other?
Where can I get a hold of an "old Jacobs Manual" so I can read up on this type of stuff? I did a quick search on the net for Jacobs Manual and did not get anything productive.
Thanks for everyone's help.
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zzark
*GenII*
7/05/2006
21:52:01
| RE: Plug Indexing
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You CAN index without using any washers, if you are lucky.
For a V6, buy 8-9 plugs. Try each plug in a different hole until you find the one that lines up between 11 and 1 o'clock.
The last time I indexed, I used only 1 washer.
And that was with only 6 plugs, no extras.
zzark
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Obio3
Dodge Dakota
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7/05/2006
22:36:27
| RE: Plug Indexing
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If you are really going to get serious about playing with indexing, Not one person gave a valid explanation of adjusting the DEPTH. this is so important, it can not be over looked. And it is tricky to do. You need to cut a plug end for end leaving just a touch over half the plug to thread into the engine. The purpose is to determine the actual depth a given brand plug will be placed in any given cylender.Using this half plug to compare depth with each new plug gives you the required depth guage you will be needing. In otherwords, If you get one to shallow exposing just one head thread or even half of one head thread. your going to eat that thread off the head. untill that happens, that thread will be a hot spot and you have given yourself spark knock. Now lets say you go a bit deep. now you have a thread or part of a thread on the plug in the cylender and same thing. spark knock from the glow plug you just made by accident. Bottom line is. You have little room to experiment with and absolutely need extra plugs so you can mess with this adjustment. Indexing plug washers are mandatory to do this unless you can get lucky as mentioned in a post above and what ever you do. ONLY ONE WASHER to a plug.More washers require over tightning the plug to keep it from coming lose causing the plug to run way to hot. normal tightning will end up backing the plug out and now you really are in trouble. And just to top it all off. After all this messng around you absolutely will learn a very useful lesson. Some things just are not worth learning about because this is one of those old hot rod tails that MAY have had some value on a carbed engine but with the spray you get on our engines it's a joke on you .
So many problems .... So little time
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The Purple1
DakotaEnthusiast
7/05/2006
22:56:02
|  RE: Plug Indexing
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Hi, Baller04B!
My input, for anyone who cares to read... :-)
You can index without using those troublesome washers; do just like zzark said. Take his advice if you want to try this "tweak".
My approach to this was indeed to buy two sets of spark plugs, use a Sharpie marker to make a line from the open side of the gap ALL the way up-- even the terminal nut-- and choose the one that when installed one at a time, oriented the gap the closest to the intake runner. This would probably be the best you could do with the heads installed. Yes, the plug heat shields must be "missing" for you to see your mark! Mine left the truck in the first month I owned it...
It was just an experiment for me; an hour or two and $20 or so in plugs. And in my instance ('99 3.9) I noted little or no difference on the "butt dyno".
Actual very-high-performance and race engines sometimes see a dramatic increase from plug indexing, though on your typical street vehicle I doubt there will be any gain that can be noticed...
Whatever you do, have fun!
P.S. Hughes "Stage II" upgrade in progress!
Extreme Velocity Intake, 52 MM Holley Billet, Ported, Hughes Plenum Plate, Perma Cool Fan, Jacobs Pro Street, Moroso Ultra 40, Bosch 4, Superchips, CPS, IAT Mods, Dynomax Ultra Flo, Transgo, SLT Trim, Diamond Heads & Corners, Clear Tails, Hood Pins, APC White Gauge, PML Polished Trans & Diff Covers...
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The Purple1
DakotaEnthusiast
7/05/2006
22:59:33
| RE: Plug Indexing
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Forgot one more thing!
Check your local Borders Books for Dr. Jacobs' manual. That's where I last saw one not too long ago. Look in the automotive section.
Cheers!
Extreme Velocity Intake, 52 MM Holley Billet, Ported, Hughes Plenum Plate, Perma Cool Fan, Jacobs Pro Street, Moroso Ultra 40, Bosch 4, Superchips, CPS, IAT Mods, Dynomax Ultra Flo, Transgo, SLT Trim, Diamond Heads & Corners, Clear Tails, Hood Pins, APC White Gauge, PML Polished Trans & Diff Covers...
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Baller04B
Dodge Dakota
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7/06/2006
07:17:22
| RE: Plug Indexing
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Thanks for everyones help.
This site and the people have been very helpful in the 9 months or so that I have owned my dakota.
I read the posts daily and they are all helping be expand my knowledge in this ever growing interest of mine.
Thanks again.
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Obio3
Dodge Dakota
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7/06/2006
20:45:15
| RE: Plug Indexing
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Can you not get a new one? . I got one. Have had it for many years. Lot of things in it are not usable for my aplications . Lots of racing type stuff. but there is some interesting reading also. If there no longer available, I'd say they just might be getting pricey if there in good condition.
So many problems .... So little time
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bludak
Dodge Dakota
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7/07/2006
13:24:22
| RE: Plug Indexing
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I really don't know why you would bother to index on the 3.9. You will see nothing at all. Only high performance race engines will benefit from this procedure. I appreciate that you want to learn, but do it in a different manner, somewhere that will make a difference.
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shatto
Dodge Dakota
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7/07/2006
20:10:59
| RE: Plug Indexing
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The preceeding is why I put the Jacobs manual away. He was addressing Drag Racers. It is interesting stuff to have a basic knowledge of it.
Problem with the 3.9?
Cylinders are a fixed capacity, transmission and rear-end have certain gear ratios, wheels rotate so many times per mile.
In otherwords, we can tweek a bit, but physics stays the same.
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