Do I have this right...ignition help?
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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=138174
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Topic: Do I have this right...ignition help?
Posted By: rasman57
Subject: Do I have this right...ignition help?
Date Posted: 07 May 2017 at 1:09pm
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My 12 volt converted (alt/negative ground regular points) D -14 suddenly quit while mowing. Just like the switch was flipped. Suspected ignition since it never missed a beat and good gas etc. I found the points opening and closing with visible arc when cranking. Coil shows power with the center wire pulled from the distributor cap and held close to the engine to see a spark............but the spark plug wires to plugs do not. Has to be the cap or rotor I say but the rotors shows continuity from the center to the contact sweep. Cap contacts were cleaned with my pocket knife and they look ok. Not even a tiny visible crack in the cap. Rotor turns etc.
A new set of points, rotor,cap, wires and coil are going in this week once NAPA gets them. I am guessing somehow the spark is going to ground but I am less than proficient in understanding the primary and secondary spark from the coil to the distributor and the fact the center coil wire creates a spark when held close to the engine perhaps doesn't mean a good ignition spark? I also checked each plug wire from the cap to the plugs and got no spark on any of the 4. I won't be surprised if the new gear solves the problem but I sure like knowing what failed.
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Replies:
Posted By: Gerald J.
Date Posted: 07 May 2017 at 1:29pm
Rotors sometimes burn through the insulation and short out the spark. The spark from the bare coil wire at atmospheric pressure should be at least 3/8" long and blue. A yellow spark indicates a bad condenser.
Gerald J.
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Posted By: jaybmiller
Date Posted: 07 May 2017 at 1:30pm
the CAP is 'grounding'....
as you have spark to the center wire( from coil and no spark at any plug, it has to be the cap or......................
the rotor isn't seated right....
or...
the cap isn't seated all the way down and locked properly...
Jay
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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Posted By: DougS
Date Posted: 07 May 2017 at 3:26pm
You probably have a carbon track in the cap that is shorting the cap center to the distributor metal. A new rotor and cap should fix the problem. While you're at it, inspect your plug wires. If they're showing age it would be good to replace them too.
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Posted By: Ted J
Date Posted: 07 May 2017 at 9:51pm
DANG,,,,,,,I was down by Shari Ralph and if I had only known...... I coulda let the rest of the family come back to WI and I could have taken the train. Give Danny Raddatz a call or a PM and he'll help you out if he has the time.
I'm thinking ,,,,,,,,, (I know, it hurts),,,,,,,,
Usually if the condenser goes, it'll give you a warning. I have to agree, maybe a cap. Did the timing jump? Check from where No. 1 is to the cap when firing. I think more so that the rotor is the culprit. How many hours on the cap and rotor? Pretty cheap to replace both... Try some WD-40 inside the cap first off to see if that helps. VERY little, but it should get rid of any water and will help the spark. When you see No. 1 spark, WHERE in relation is the No. 1 on the cap? Hope this helps ya buddy!
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"Allis-Express"
19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17
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Posted By: rasman57
Date Posted: 08 May 2017 at 11:25pm
Well I was thinking cap as well...either that or rotor but the cap sure looks okay and I have seen some of those tiny cracks with the hairline trace before but not this time. I will replace parts one at a time and see where the spark ran off to ground. Always a mystery for me when the electrons are involved but at least I have narrowed the suspects. I been wanting to add a Petronix ignition to this tractor as my other 3 all have been converted and was waiting until tune up time ... The center coil wire has spark but not sure how good and for sure the cap is not distributing that spark once it gets plugged in as the spark plugs ain't getting any. It seems so basic that it has to cap or rotor but I am still wondering if the coil is bad . All the parts are a few mowing seasons old so I ain't complaining but it is a bit of a surprise the way it tracked down to no spark at the plug wires.
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