Plug fouling on Cat small 20

chugwater crawlers
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17 years 1 month ago #3465 by chugwater crawlers

Plug fouling on Cat small 20 was created by chugwater crawlers

I have Cat 8C20 with Autolite 3007 spark plugs. Three of the cylinders plugs show dry soot fouling while one cylinders plug is clean. Any ideas? It starts and runs okay. I can hear a slight miss at low idle. Thanks in advance!

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biggastractor
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17 years 1 month ago #3467 by biggastractor

Replied by biggastractor on topic Plug fouling on Cat small 20

CC,
Do you mean 3007 or 3077 plugs? It is my understanding that the 3077 is hotter than the 3076 and I have had good luck with the 3077's. I don't know what a 3007 is. Could be lots of other things causing the fouling too.
Biggastractor

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Old Magnet
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17 years 1 month ago #3468 by Old Magnet

Replied by Old Magnet on topic Plug fouling on Cat small 20

A 3007 plug does exist but it is a 14mm vs the 7/8-18 thread units.
Normally the 3076 or 3077 Autolite is a good plug.
Check the clean one, it may not be firing.
Over rich mixture due to high float level, internal leakage of fuel or restricted air supply are the usual culprits.

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chugwater crawlers
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17 years 1 month ago #3471 by chugwater crawlers

Replied by chugwater crawlers on topic Plug fouling on Cat small 20

Sorry that was a typo. It is a 3077 spark plug. I will try to lean out the mixture and see what happens. I will also check that clean plug!

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TerryinNorCal
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17 years 1 month ago #3481 by TerryinNorCal

Replied by TerryinNorCal on topic Plug fouling on Cat small 20

Just a thought...helped a friend out on his 22 ( see previous post on soot fouling). Found out after a thorough carb adjustment, all things fine so far on a clean burn using the 3077's. I think yours may be the same problem, only you may have a dead/intermittent plug wire and she's richen'ed up to compensate, hence the miss. Good luck in tracing it down.

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