Carbon build up on spark plugs

Trucks used by the U.S. Army in world War II that were 2.5 tons and larger. Such as Studebaker US-6, International M5-6, 4 Ton tractors (Auto Car, etc.), 5 Ton (Corbitt, etc.), the Dragon Wagon, and any other trucks 2.5 tons and over.
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First Lieutenant
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Carbon build up on spark plugs

Post by sixbysix » Mon Jul 03, 2017 4:16 am

Hi all - some questions for the brains trust ....
I have a question re Stude US6
I seem to have a lot of carbon building up on the plugs very quickly within a half hour drive - and wondering about your thoughts
- have just re-adusted the points and timing but this hasn't solved the problem, Am getting some new leads as have done 35000 km ( about 25000 miles) with these so thought might try that and see if that helps
other than that all I can think is that the fuel mix might be too rich - but I haven't done any carby adjustments at all to influence this ... your thoughts ....?

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Brigadier General
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Re: Carbon build up on spark plugs

Post by Bill_Wolf » Thu Jul 06, 2017 7:45 am

If nothing visual jumps out at you I start with a Vacuum Gauge.

While not conclusive if there is something off it will show itself here. This is not a fool proof diagnostic tool but a quick cheap way to find potential issues.

1942 Chevy 125 Crash Truck from Dow AAFB,
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1944 M29C Weasel (x5)
1945 CCKW 353 A2 Open Cab "Air-portable"
1943 M5 High Speed Tractor
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1942 M-1 Fruehauf Searchlight Trailer (G221)
1942 M-17 Fruehauf Quad 50 Trailer (G221)
1942 M-10 Ammo Trailer (x3)
194? Steel Ben Hur (x4) 194? Wood Ben Hur (x2)
1945 Case VAIW-3 Aircraft Tug
1943 Case VAI USAAF with Mower
1944 Clark CA-1 Airborne Dozer
1944 PE-95G, 1944 PE-99B

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