VetNutJim

I've seen you advocate "reading" plugs in many,many post and would like to know what precisely to look for during "reading".

Although I've been "reading" them for many years I feel probably I've just been "looking" at the pictures without reading the words.

Could you give us all a "Grumpy's Final Answer" on plug reading and detail not only what to look for, but where to look for it?
IE: Where or what exact part of the plug to look for certain "signs". Such as the insulator, the plug base, the electrode tip and ground element?

Could you throw in a few pictures?

IOW, could you take the time to teach some of that don't know, how to read?

Thanks in advance.

vernw

iTrader: (2)

Great Idea!!! Please, Grumpy?

Dave_Jones

He already did.

http://www.diy-efi.org/gmecm/papers/plug_cuts.html

VetNutJim

That's a good article..... but he writes so much better now.

I'd still like to have a "Final Answer". With pictures to accompany the explanations.

He knows way more that he could pass on to us than whats in that article.

I've been "reading" them for over 40 years but would really like to absorb more information that might allow me to move to the next level and be a Zen Meister Plug Reader.

Grumpy

It's hard to really explain plug reading, verbally.

Without a magnifing glass the details can be totally lost.

As I mentioned in the Chip Talk thread, I'll be at Bowling Green, with a WB, and all the time in the world to play show and tell that would include plug reading.

Circle track Magazine in like 95 had a series on plug reading by Smokey Yunick where they cut plugs apart, so the camera could get shots of the innerds. I lost the mags when a tornado rearranged my library some years ago. Maybe someone could research things, and find a the two magazine issues where they had the pics. Actually there were several, one on unleaded race gas, and I think the other on Alky. Both are the premiere articles on the matter, IMO.

Second place is the Dr Guide to Optimizing your Ignition system, and the Buick Power Book. At least in the early versions of the Dr's Guide, btw penned by Jacobs of Jacobs ignitions.

NTK and Champion on their we pages have some vaque info..

VetNutJim

That's why I feel my plug reading skills may need to be honed.
It's kind of like "describing" a certain "shade" of pink to someone that doesn't know what pink is.

But there must be some information that goes beyond the usual 4 or 5 pictures one sees on the parts store counter top.
Those always show plugs in quantum leaps of "this is good" to "this is bad". I'd like to know the 'in between' parts.
Probably everyone that does their own plug & oil changes knows the rough insulator color 'reading' part.

I'm specifically interested in the portion of the plug that becomes part of the combustion chamber.
The base of the plug, or part that has the threads on it.

Question:
What about the plug 'base' or ring that becomes part of the combustion chamber?
Is there some information that can be gleaned by looking at that specific portion of the plug?

Is the insulator the only part of the plug that "has writing" on it, no pun intended.

Question:
What about when you have an engine that consumes no oil but that particular portion of the plug is black and a little soot will come off on your finger as you rub it over that part of the plug....BUT the insulator is white.

What if there are NO deposits on the plug base ring? Is that good or bad?

What is the best way to get a reading on a vehicle that doesn't have NEW plugs and the actual reading may be done after a couple thousand miles of driving..or is it even possible to obtain other than a 'rough' reading after this many miles?

It's also VERY difficult to do a high speed run on the highway, cut the engine and coast to a stop and get out to check the plugs.
Is there a preffered way to do this for those of us that don't go to "the track".

Does gasoline brand/additives affect the reading?

I like to run Marvel oil in my gas. Will that 'tint' my plug reading?

Nothing but questions....
But I've found the more I KNOW, the more I realize I don't know.
About the only way to learn is to read or ask someone that does know.

Grumpy

Answers hidden in quoted text.



The more I know the more I try to share, cause it seems if I don't then it spills out, and forgotten. Memory needs exercise, especially as you get older. The old dog and new tricks is alot more accurate then you can imagine, IMO.

While I may write alot, when around the gurus, I just ask guestions.

VetNutJim

Thanks much for the answers, they are very appreciated.
Will be tuning tonight and reading plugs. (and getting my hands burned )

"Knowledge is the most valuable thing you can give someone"
j.alford

rattle

heres some food for thought on spark plugs. If you really think about it the only outcome from the combustion process is the production of soot, soot is black and thats it, the browns and blacks and greys seen on spark plugs are a result of fuel additives and so forth, Gordon Jennings wrote an 8 page long explanation of spark plug reading here http://www.strappe.com/plugs.html

He is from the motorcycle community but a spark plug is a spark plug.

At the end of the day you want to have to the correct heat range spark plug with just an ever so slight ring of soot way down at the bottom of the insulator.

I use Gordons methods on both two stroke and 4 stroke and it works just fine for me.

Grumpy

If you really want to boil it down to the basics, all a spark plug does is provide an air gap.

Gray shading of the proclean can be from the additive package, OR a sign that there is trace detonation going on. Knowing the difference, is what's called having *the edge*. Knowing what the glue seeping out from the center electrode to porclean has a meaning, the speed at which the center electrode erodes has a meaning.

And the soot ring, on a emissions tuned vehicle, may at times, not even exist.

What was true about gasoline in the 70s and 80s, has varied some today. Not to mention that there are 55 different brews of fuel available in the US today, and that there are summer and winter versions of all 55.

Plugs are the eyes, into the combustion chamber, and knowing what your looking at is important if you into getting the tune correct.

So while what he's said in general is true, there is more to it.

rattle

I totally agree with you Grumpy, I first learned to read spark plugs on my two stroke snowmobile engine, electrode spark line for timing, boiling cement for wrong heat range, peppering of aluminum on ceramic for you need new pistons now, big chunks of aluminum on electrode You actually still have compression?,

thats what makes the article i posted good,
first get proper heat range
then get timing right
now start leaning things out

It takes much study to find out whats going on with spark plugs. I think one of the best places is at the 1/4 mile track, walk around the pits and look at others peoples plugs if they will let you. Only practice can tell you what you are seeing.

Grumpy

I've swung many a wrench for free, for the opportunity to just work with guys that were in the know. Volunteering to work on a team can have some huge long term rewards. If even on an SCCA lil car, if you get involved with the right group, it can be as educational as working for the likes of Warren Johnson.

va454ss

iTrader: (1)

I've read so many things about plug indexing lately. Seems there are varying opinions based on whether its N/A, supercharged, and combustion chamber design.

What's the logic behind orienting the gap toward the intake valve?

Grumpy

So the relatively cool incoming charge cools off the center electrode to help fend off detonation.

Doing it to find HP on a street motor, never got me anything.
But, it's great for really making sure all the cylinders are even in fuel distribution.

11sORbust

do you think that setting up the plugs that way is good? I mean think about it, sure the plugs are clocked to a "better" position. But using the shims to do that will make the plugs sit back futher in the chamber. So in turn you'll have plugs that vary in depth, in the hole. I would imagine that would effect the heat range indirectly.......at least not be as good as plugs that all are at the same depth. yes?

Dave_Jones

With a little trial and error, you can index plugs without using any shims.

I have a couple of little threaded aluminum disks (they look like a really big hex nut) that I've etched marks in for each of my engines -- just by threading the plug in, and noting where the electrode points, shows which cylinder(s) that plug would be a good fit in. Only takes a couple of minutes to sort out a set of plugs that way.

va454ss

iTrader: (1)

Quote from May 04 PHR:

"Although any differences are normally small, another move made to optimize spark results is known as plug indexing. This is an attempt to position the plug electrode such that the spark produced has the greatest exposure to the cylinder's charge. In general, it seems that best results are achieved if charge motion is through the electrodes (i.e. moving about 90 degrees to the side electrode). For "wedge" and "bathtub" style combustion chambers, positioning the side electrode toward the roof of the chamber generally works best."

Thoughts?

RBob

iTrader: (1)

Spark plug indexing was originally done to position the ground electrode away from the piston dome so that it wasn't
hit thereby not altering the gap.

RBob.