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spark plug reading

spark plug reading
Dan86CJ7

Dan86CJ7

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Vehicle(s)
1986 cj7 258(rebuilt motor/comp cam/weber32/36) T5 300 tcase d30 front(locker/4:10s)
AMC20(locker/4:10s),4"lift,33"s
tried but cant seem to find any good color charts. was curious if any one could help look at these plugs and maybe point me in a direction to poss. repair, runs great,but super rich, gas whore!! take a look at the pic and let me know what you guys think..tks all:chug:
View attachment 16415
 
If those are in order I would have to say I think the #5 has a crack in the head. Using a little oil? :D

Gas hog and jeep are the same word in two different languages. What color is the ash? you are looking for a light brown/tan.:cool:
 
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the worst you see is #2...some of the deposits look whitish but mostly tan/brown:mad:..those have maybe 10k on them..will have to monitor the oil, just changed on friday.
 
Generally reading spark plug color isn't as easy as folks think. To get a proper reading you need to drive down the road at speed, say 65mph. After a while doing this speed you need to push in the clutch and shut the engine off. This ensures you will get a reading at exactly the right temp. Slowing down drenches your plugs with gas changing the reading completely.

But, your plugs deffinately show a problem. Depending on a few variables. How old are your plugs? The white crystles look like you might be using a lot of additives in your gas. I will say this, changing those plugs will show a deffinate improvement in the way your engins runs. I'd put in a new set and watch them closely. Say no more than every 1,000 miles. The plugs also look a little cold (range a hot plug v.s. a cold plug).
 
Tell me about the ignition system. Stock, team rush, MSD??:D
 
i dont use fuel additives at all, when i say it runs rich i mean rich, when i got the weber it seems to run best w/ mixture screw in just about all the way in? some are caked in brown, some are just white. i changed them friday before i went wheelin on saturday..even with those plugs it ran good, barely a miss...
 
did the nutter,upgraded the cap,rotor,ect. and a msd blaster coil
 
The mixture screw is just for the idle. once you open the throttle plate you are on the main jets. I am not big on the Webber so I would not bet my life on it but I think the only way to adjust main jets is to change them.:D
 
Dan86CJ7 said:
tried but cant seem to find any good color charts. was curious if any one could help look at these plugs and maybe point me in a direction to poss. repair, runs great,but super rich, gas whore!! take a look at the pic and let me know what you guys think..tks all:chug:
View attachment 16415
Click to expand...


:)The First 3 on the left look used but OK the next 3 on the right all seem to have issues. The deposits on the right are from oil which could be rings or valve guides or both............hard to tell what the condition of the electrode is versus the ground strap..........if it is eaten up the mixture is to lean or hot but since it burning oil it will also attack the tip.

Just cause it burns allot of fuel is really not indicative of a rich motor. If it smells rich to the point it's uncomfortable to breath standing near the exhaust it is Rich. Allot of motors burn excess fuel because of the incomplete ignition process brought on by weak cylinders, weak ignition system and or a bad carb that is not processing fuel correctly.

As a crutch you step on the pedal harder to get the same amount of work out of the engine thus it burns more fuel.

I would run a compression and a leak down test on all the cylinders. I would also look over your complete ignition system and pay close attention to grounds........also run and ohm test on your spark plug wires. Once you have a good feel for the rest of the system working properly put a new set of plugs in there of the correct heat range and drive it at freeway speed for 30-45 minutes or so......and then pull the plugs....driving it for a few miles back home from the freeway will hardly make a difference at all for a plug reading.

I think you will find you have some issues either in rings or the cylinder head valve guides or the valve seats...........Sorry but the plugs look like a typical worn out motor.

:D:D:D:D
 
Dan86CJ7 said:
tried but cant seem to find any good color charts. was curious if any one could help look at these plugs and maybe point me in a direction to poss. repair, runs great,but super rich, gas whore!! take a look at the pic and let me know what you guys think..tks all:chug:
Click to expand...

I'd be inclined to get a compression tester and match the cylinder compression number against the plug. They all look pretty grim, but worn-out piston rings or some serious vacuum leaks could force you into a rich mixture corner.

Cheap guy like me uses a read-and-lock gage with just a rubber "bullet" tip to seal off one spark plug hole at a time. It takes a while, but gets you one of the answers you need.
 
Tks for all, I'll check compression that's quick, #2 is always the worst. I never had the head checked when I sent out the block for new bearings. I did lap in all the valves, it seemed ok. So a head issue could be possible. I'll get back with readings as soon as I take me
 
Dan86CJ7 said:
Tks for all, I'll check compression that's quick, #2 is always the worst. I never had the head checked when I sent out the block for new bearings. I did lap in all the valves, it seemed ok. So a head issue could be possible. I'll get back with readings as soon as I take me
Click to expand...

I can be wrong real easy on this one and hope I am. there is something loading that plug a little extra and allowing a foreign substance, oil or water, into the chamber. I have seen this happen with cracked heads. BUT I would bet that the machine shop would have done a mag flux on the head before spending time on it. There is something in there that does not belong. With a decent ignition and a decent fuel to air and you should be able to get 50K miles from a set of plugs with no problem.

Cant wait to hear about compression test.:cool:
 
ok,sorry for the delay, as i stated head never went out..just the block for crank/rod/cam bearings. so ill post a pic of the new set of plugs, this is about 400 miles of driving and a day of wheelin. And finally took compression test...i didnt think there was a problem here but here are the #
#1--168-170 psi #2--170 psi #3--170 psi #4--175 psi #5--175-180psi
#6--172-175 psi.
These #s look fine to me, Any ideas would be great... plugs always look this way when taken out, usually 10k or so. but seem to perform ok, my gas mileage just sux!!!
View attachment 16554
 
looking at your plugs and seeing the carbon build up on one side usually indicates worn valve guide. With the compression numbers I see you will probably be fine with a little head work down the road sometime.
Reading spark plugs by color has gotten more difficult with unleaded fuel.
The lead helped to give those nice colors we saw in the past.mike:)
 
What plugs and PN are you run'n? What are you gap'n them at?
When was the last time you replaced the dizzy cap, rotor and sp wires?
FWIW: I use Autolite 985
LG
 
the cap and ect. are not too old.. couple yrs(20k or so) and plugs i get right from the jeep dealer i work for and its what it calls for per the parts manual..i think RFN14YC....but would have to double check the box tomorrow.And .040 gap. jeep seems to exibit no real running issues... the build up is what concerns me.
 
they are champion RFN14LY plugs
 
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:popcorn: im hoping its not a head!!!
 
I had a cracked head on my dd pickup for around 75k until a rocker arm broke. It did go through the coolant though.
 
If I chose to just pull the head..is 4.0 the better option.
 
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