Adjust plug coloring spark plug gap - JeepForum.com
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post #1 of 45 Old 12-05-2019, 03:08 PM Thread Starter
agear
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Adjust plug coloring spark plug gap

My plugs came out looking rich when I checked them last week. I replaced 1 of the plugs but when I checked it today it was bone white. I put a big gap in it before I put it in and am assuming that is why. I thought I put the gap where it was on the previous plug but I guess not. I had help from expert work on a running lean issue and we adjusted the gaps on the plug and they colored good after that. I think I just answered my own question . I can adjust the plug to get it to color correctly. But I guess I was wondering if carbb tuning should be addressed at this point ....


1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #2 of 45 Old 12-05-2019, 03:43 PM
Matt1981CJ7
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What ignition are you running?

Matt


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post #3 of 45 Old 12-05-2019, 04:00 PM Thread Starter
agear
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Originally Posted by Matt1981CJ7 View Post
What ignition are you running?

Matt
I run the stock ignition. Stock coil stock module stock distributor

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #4 of 45 Old 12-05-2019, 04:48 PM Thread Starter
agear
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I regapped the plug .035 let it idle for 10 minutes and that plug was still too lean.im wondering if it's getting spark like it should

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #5 of 45 Old 12-05-2019, 05:17 PM
Fourtrail
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You need to go out and put a load on the motor, then take a look at the plugs. A lean idle is normal, carb should be adjusted for best lean idle.
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post #6 of 45 Old 12-06-2019, 07:46 PM Thread Starter
agear
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Originally Posted by Fourtrail View Post
You need to go out and put a load on the motor, then take a look at the plugs. A lean idle is normal, carb should be adjusted for best lean idle.
I've heard of lean best idle. I checked them today after driving and it was still lean . When I was tuning before I would do an interstate run then check the plugs. Then let it idle with no accessories on and check them and both times the plugs had color. I'm pretty sure I'm getting spark on thar cylinder because I've driven without a spark plug wire on - it runs rough. Mine is not running like that.

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #7 of 45 Old 12-06-2019, 08:39 PM Thread Starter
agear
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Update I just put a clean plug in one of the other cylinders and ran the jeep and it came back white. I'm running lean. After I turned the jeep so the plugs colored good I turned up the idle speed screw to bring my idle rpms up . Would that lean it out ?

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #8 of 45 Old 12-07-2019, 07:48 AM
Matt1981CJ7
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agear,

It takes more than a few minutes of run time to color a plug. The plugs in the pic below had about 1000 miles on them.
They are the color you are looking for.

BTW, the wider the gap the leaner the plug will burn. Also, a cylinder that is not firing, or has a weak spark, will foul the plug dark.


Are the new plugs you are installing the same as the old ones?

Matt
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post #9 of 45 Old 12-07-2019, 08:49 AM Thread Starter
agear
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Quote:
Originally Posted by Matt1981CJ7 View Post
agear,

It takes more than a few minutes of run time to color a plug. The plugs in the pic below had about 1000 miles on them.
They are the color you are looking for.

BTW, the wider the gap the leaner the plug will burn. Also, a cylinder that is not firing, or has a weak spark, will foul the plug dark.


Are the new plugs you are installing the same as the old ones?

Matt
Cool thanks. It was just one plug I had lying around but yea it's the same 985 copper autolite

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #10 of 45 Old 12-07-2019, 09:09 AM
pedal2themetai
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HI, You can't check one plug and get a accurate reading on your motor .. on a 6 or a 4 cylinder plugs close to the carb can run rich while plugs at the front or back well run lean.. You well also get a different looking plug when checked after a fast run and shut off before it gets to idle. letting it idle to check you well only get what its doing at idle and not at speed.
OH and as Matt said it takes longer than one short run to give you accurate reading..
good luck
tim
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post #11 of 45 Old 12-07-2019, 05:29 PM Thread Starter
agear
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Quote:
Originally Posted by pedal2themetai View Post
HI, You can't check one plug and get a accurate reading on your motor .. on a 6 or a 4 cylinder plugs close to the carb can run rich while plugs at the front or back well run lean.. You well also get a different looking plug when checked after a fast run and shut off before it gets to idle. letting it idle to check you well only get what its doing at idle and not at speed.
OH and as Matt said it takes longer than one short run to give you accurate reading..
good luck
tim
Hi, when I was tuning this thing months back I was using new plugs and they.colored right after my first 15 mile interstate test run. But never the less the new plug I just put in did color now that I checked it again just now so..... I checked the rest of my plugs and they look fine to me. Maybe slightly rich but no problem. It's better mechanically to run rich than lean I was told because you dont want to spark knock or burn a piston. The question now is will the plugs clean themselves enough to show white so you can tell if they're lean ? I would think so bec as use you dont go out and buy new plugs just to do a check I think. I also think my fuel system isn't swirling the air and fuel and some intakes and carbs do but its doing a lot better now that I roughed up spirals in the adapter plates and adjusted the gaps on the plugs.

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #12 of 45 Old 12-08-2019, 07:28 AM Thread Starter
agear
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I went on s test drive with new plugs this morning and plugs were clean. So I went again and they git a little color. I'm thinking it's running leaner because of the cold .
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20191208_081721_1575811671451.jpg  

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #13 of 45 Old 12-08-2019, 08:04 AM
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Quote:
Originally Posted by agear View Post
I went on s test drive with new plugs this morning and plugs were clean. So I went again and they git a little color. I'm thinking it's running leaner because of the cold .
Colder air has more density, therefore the 'mixture' will move towards a slightly leaner ratio, IF you make no other changes, AND IF you aren't running a controlled ignition system that self-compensates.

You have a choice to tune the basic idle to 'best idle' or 'best vacuum'. Best vacuum is recommended by Holley and most sources I have come across. This will make idle a tiny bit rich which can help with transition from idle to main circuit in the scenarios I am familiar with. Best idle on my current motor is 950 rpm. Best vacuum is 750 rpm.

As mentioned, carbed/TBI inline sixes will run 3-4 best with 1-2 and 5-6 being progressively leaner due to the placement of the fuel distribution in the center of the motor. That is of course assuming you're only running a single carb and not some custom, wacky multiple Weber thing.
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post #14 of 45 Old 12-08-2019, 08:11 AM Thread Starter
agear
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Quote:
Originally Posted by gutthans View Post
Quote:
Originally Posted by agear View Post
I went on s test drive with new plugs this morning and plugs were clean. So I went again and they git a little color. I'm thinking it's running leaner because of the cold .
Colder air has more density, therefore the 'mixture' will move towards a slightly leaner ratio, IF you make no other changes, AND IF you aren't running a controlled ignition system that self-compensates.

You have a choice to tune the basic idle to 'best idle' or 'best vacuum'. Best vacuum is recommended by Holley and most sources I have come across. This will make idle a tiny bit rich which can help with transition from idle to main circuit in the scenarios I am familiar with. Best idle on my current motor is 950 rpm. Best vacuum is 750 rpm.

As mentioned, carbed/TBI inline sixes will run 3-4 best with 1-2 and 5-6 being progressively leaner due to the placement of the fuel distribution in the center of the motor. That is of course assuming you're only running a single carb and not some custom, wacky multiple Weber thing.
That's what I thought. I didnt know best vacuum and best idle were different.......
When I turned this last time I tuned to best vacuum but then to richen it up i backed out the mixture screws 1/2 to 3/4 turns

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #15 of 45 Old 12-08-2019, 08:15 AM
Matt1981CJ7
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Agear,

A picture with better light would make it easier for us to comment.

That said, those plugs don't look bad to me, but 2 short trips isn't enough to get an accurate reading from the plugs.

Matt


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