Help reading spark plugs

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Heywodja

Heywodja

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Ok, so I have these auto lite 3923 in my 72 dart, edelbrock 1411 carb right outta the box.. Running aixture of pump gas and 114 octane. This is after about 30 miles of city/hey driving

Trying to get a good read on the plugs looks it is slightly lean, and has a slight yellowish tone
Thanks in advance!
 

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That looks pretty good actually. Make a 1/4 mile pass and shut it down afterwards and read then. If it is lean that is when you will see it.
 
Cool thanks, will try to find a spot to do a hard 1/4 got one more pic.
 

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mguner said:
That looks pretty good actually. Make a 1/4 mile pass and shut it down afterwards and read then. If it is lean that is when you will see it.
Click to expand...

Sure does.

I posted the chart in the other thread.
 
Cool thanks,

They should make a sticky for this subject!
 
how many ways can i say LEAN? LEAN and LEAN AND LEAN... try one or steps colder plugs. and reset the float level to 5/16. but not any higher. dont for get with the lid upside down a low number is a HIGHER fuel level.
 
The more 114 you run the leaner it will get. Do you have the compression that requires high octane? The second shot does look a little brighter. A good zoom shot would really tell.
 
i am running the hughes stage 2 (firstgen) 360 heads w/2.02 intakes and 1.62 w 58cc chambers pistons have positive deck height which nets roughly 10.5 ~10.7 @ 4800ft elevation, where I originally built the engine.

Now I am in Dallas sea-level basically, it will not run on 93 pump gas without excessive detonation, so i blend the 114 5 gals per tank.

It looked lean to me as well, but it does have a pretty good burn pattern, and the heatline on the ground electrode is good as well.

I am going to order the strip kit for this tomorrow.
 
Modern fuels burn clean and reading plugs can be difficult.I had very white plugs and thought i was lean.I installed o2 sensors and a wideband a/f gauge and found it was actually rich at idle and cruise.
...install 02 sensors and wideband a/f gauge and you will know for sure.
 
A 3 is on the cold side for plugs. Especially for the street. I think just a hair rich but that might be the cold plug. Like to see a 5. Now what are you all looking at? I'am looking at the metal ring the ground strap is welded to. Looking for a dark grey,not black. Your close. Google "plug reading 101 by Mike Canter". This is to tune for power. Go leaner on the rods for cruising.
 
hangn0ut said:
A 3 is on the cold side for plugs. Especially for the street. I think just a hair rich but that might be the cold plug. Like to see a 5. Now what are you all looking at? I'am looking at the metal ring the ground strap is welded to. Looking for a dark grey,not black. Your close. Google "plug reading 101 by Mike Canter". This is to tune for power. Go leaner on the rods for cruising.
Click to expand...

I thought the 9yc was the stock heat range plug for a hi compression 340, so i was just figured that would be the logical choice.

So what I think you are saying is a "hotter" plug would have an effect on mixture. Or is it combustion/ flame propagation?

I was looking at his info (Mike Carter), I guess I will order a strip kit for the eddy, and see how she does. I was a little confused between the insulator and that outer band, I've always looked for that tan colored insulator in the past.

The grounding electrode seems to have a flame travel about 66% of it's length, so it seems to me to be pretty good.

I will see about getting some photos using a real camera instead of the phone camera.
 
rejetting Carter / Eddy carbs is NOT stright forward. the short story is you can NOT change the the Jet and rod at the same time and know what your change was, by guessing. i have a computer program that i wrote years ago that can calculate it. i have posted the link on this site some time ago. if i can dig it up ill try to post it. but my family life is keeping very busy.
 
IMOHO First thing to do with a eddy is check your vacuum and put in the proper color step up springs. If it's out of the box and you have a cam, they need to be changed.
 
moe7404 said:
rejetting Carter / Eddy carbs is NOT stright forward. the short story is you can NOT change the the Jet and rod at the same time and know what your change was, by guessing. i have a computer program that i wrote years ago that can calculate it. i have posted the link on this site some time ago. if i can dig it up ill try to post it. but my family life is keeping very busy.
Click to expand...

Cool that calculator would be pretty useful. Will alos prolly look into the 02 sensor deal too.

fklskv said:
IMOHO First thing to do with a eddy is check your vacuum and put in the proper color step up springs. If it's out of the box and you have a cam, they need to be changed.
Click to expand...

I have this cam in the pic, and it is pulling 14+/- at idle. Idle does seem to be a little rich based on the exhaust fumes, but that is why I put the new plugs in to see what condition my condition was in.
 

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Heywodja said:
Cool that calculator would be pretty useful. Will alos prolly look into the 02 sensor deal too.



I have this cam in the pic, and it is pulling 14+/- at idle. Idle does seem to be a little rich based on the exhaust fumes, but that is why I put the new plugs in to see what condition my condition was in.
Click to expand...

The step up spring is like a power valve in a Holly. Its HUGE.

You take the vacuum reading and cut in half to find the proper spring. You need the pink spring which is not what comes from the factory. It takes about 5 minutes to change them and you don't have to disassemble the carb or take it off the car to change them. Hope it helps
 
You said you was using autolites. Autolites the larger the last number the hotter the plug. Jumping plug brands can get confusing. Run to cold a plug and it carbon fouls. Can't read fouled plugs.
 
Hard to get a real good look at your plugs to say for sure from the pics, but they look lean from what I can see. You detonation problem is probably more from being too lean than an octane problem or a plug heat range problem.
Lower altitude tuning requires a richer mixture than high altitude. Again pointing to lean condition.
 
I figured I would just start out with the 3923, it has been a favorite for a while.

I hope to get a little more time on the throttle this weekend. It seems to run pretty good, with it's current tune.

As far as the detonation, it never has liked pump gas ever! I may have to go to another set of heads with larger chamber volume, or some aluminum ones to ween it off of the high test liquor it seems to crave.

Thanks for everyones input, I may try another set of hotter plugs in the real near future, and seriously looking into the wideband 02 sensor option as well.

I ulimately want to use a multi point fuel injection option, right after i get my HDK k-member and front suspension, get it re-painted to hemi orange and finish the interior. LOL
 
Looks overtimed with a rich idle to me. How long did it idle before you shut it off?

What's the timing set at? Do you know the initial and total numbers? Are you running the vacuum advance?

Also, if you're going to be attempting to read plugs I find it's easier to read NGK plugs due to their nickel plating. Something in the "6" heat range would be my choice, possibly the zfr6f-11 if your heads use the magnum style plug (which is what it looks like in the pics).

What part of Dallas are you in?
 
ir3333 said:
Modern fuels burn clean and reading plugs can be difficult.I had very white plugs and thought i was lean.I installed o2 sensors and a wideband a/f gauge and found it was actually rich at idle and cruise.
...install 02 sensors and wideband a/f gauge and you will know for sure.
Click to expand...

^^^THIS^^^:sign3:
 
UOP said:
What part of Dallas are you in?
Click to expand...

Actually I am here in Plano.

I have been doing just some driving on the surface streets and a few stretches on 75 up towards Allen. The plugs were pulled after about 30 or so miles.

...install 02 sensors and wideband a/f gauge and you will know for sure.
^^^THIS^^^
Click to expand...

What is a good sensor to go with? Looking for ease of install and decent readout with easy use.
 
Innovate, PLX, AEM. Use wideband sensor that comes with kit, closely follow instructions. There are specific requirements for sensor location, mounting direction, and wiring practices.
 
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