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Old 03-06-2021, 06:41 PM   #1
drolston
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Default Spark Plug Fouling

Been chasing an ignition problem all winter. Running rough; missing. Traced the problem to coil wound spark plug cables not properly seated in the distributor cap, leaving a big gap to jump. #2 and #6 were not firing.

Just installed new cap, rotor and solid core ignition cables. Starts and runs, but #2 and #6 are still not firing. They are getting spark. Replaced the like-new, but wet, NGK B6HS with a couple older but good Champion L82C plugs, and now it is hitting on all 8.

#2 and #6 were run for some time with with no spark. Would that foul them so that they would not fire when good ignition was restored?

Should I try and even hotter plug? Like NGK B5HS (if I can find them).
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Old 03-06-2021, 09:57 PM   #2
aussie merc
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Default Re: Spark Plug Fouling

any thing such as carbon oil fuel once fouled their fouled try heating the center electrodes with a propane torch might be able to clear them
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Old 03-07-2021, 08:10 AM   #3
Bored&Stroked
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Default Re: Spark Plug Fouling

I've had issues with plugs that were fouled - never correctly firing again. I've especially had this issue with Champion racing plugs - versus NGK.

One time when we were racing the FlatCad at El Mirage, the rest of the gang got to the event early and tried to start the engine and had a few things screwed up. We have multiple ignition setups for different classes - and they had a few things wrong on the configuration. They said it "popped a few times and wouldn't start" . . .

Anyway, they washed the plugs down and when I arrived there was all sorts of gnashing of teeth -> that we'd lost the magneto, that the electrical system had issues, etc.. I asked what happened . . . then asked what plugs were in it. Yep - brand new Champions (they were nice enough to sponsor us).

I told them the plugs were the issue (they'd washed them down with Akly) - everybody scoffed at me. Well, I threw in a new set of NGKs, went through the startup sequence properly and she fired right up. Should of seen the looks on all their faces!

Needless to say, they stopped questioning me on plugs and ignition issues. LOL

I've had this issue with regular gas as well . . . is just something that happens at times (especially if you have ignition issues and dump a lot of fuel down it).

I wouldn't run hotter plugs - unless you've correctly checked them with a highway load test.
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Old 03-07-2021, 09:42 AM   #4
BillCook
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Default Re: Spark Plug Fouling

In the winter I’d run hotter plugs ,but not in the summer !
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Old 03-07-2021, 10:18 AM   #5
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Default Re: Spark Plug Fouling

When Ford first went with FI people would still pump the gas while cranking engine. The plugs looked brand new but would never fire again. Ford said they were chemically fouled. Couple of plugs on crown vics were hard to get to so mechanics would replace 6 and take car on long test loop to get hot, then they would come back and replace the 2 that were to hard to get the first time.
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Old 03-07-2021, 11:01 AM   #6
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Default Re: Spark Plug Fouling

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I saw that a lot back in my snowmobiling days. Someone couldn't their sled started so they took the plugs out, looked 'em over good, and put 'em back in because they looked fine. Still no start. Put in a new set of plugs and it would start right up. Never could figure out what the actual reason was, but whenever I encounter a mysterious no start problem, a new set of plugs are high on the list.

And Dale's right; some plug brands were more prone to this than others.
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Old 03-07-2021, 11:15 AM   #7
drolston
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Default Re: Spark Plug Fouling

Quote:
Originally Posted by aussie merc View Post
any thing such as carbon oil fuel once fouled their fouled try heating the center electrodes with a propane torch might be able to clear them
I will torch the two NGK B6HS plugs that got fouled from running with bad spark plug wires, and put them back in to see if they recover their function.

As a backup, I have ordered a new set of NGK B5HS plugs, one range hotter than the B6HS. That should minimize fouling, but I will be listen carefully for any signs of detonation.
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Old 03-07-2021, 11:41 AM   #8
earlyride
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Default Re: Spark Plug Fouling

Quote:
Originally Posted by aussie merc View Post
any thing such as carbon oil fuel once fouled their fouled try heating the center electrodes with a propane torch might be able to clear them
A long.....long time ago in a gas station far....far away that I used to work at, had a plug cleaner using a media that blasted the plugs clean, that seemed to work well.
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Old 03-07-2021, 12:37 PM   #9
Bill OH
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Default Re: Spark Plug Fouling

I would be very careful in going to a hotter plug - punch a hole in a piston. I used to run H9s in place of H10s in an 8ba in the 50s and BF32s in place of BF42 in a 352 ci Ford. Had good performance with the H9s and the BF32s. I am running H10s in 81A heads on a 221. No problems with those either.
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