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Allis Chalmers Discussion Forum

Questions about AC model B, plug type, timing.

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07-18-2003 21:10:16

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Hi, I am trying to help my neighbor out with his AC model B. I spend more time working on it than him and I find that I spend much of my time undoing what damage he has already done. Questions are as follows. Book calls for AC-45 plugs, where can I find a set for it or similar replacement. Also he is using AC-45R in it and it seems to be fouling out the plugs with a weak spark (any comments on this would be appreciated). Has anybody had this happen to them. Also, how do I set the timing? I noticed a peek-hole near the bottom of the torque tube and may have found a timing mark on the fly wheel. It has a WICO magnito. How do I get this thing timed correctly? I am familiar with Farmall tractors but not this little AC model B. Any other suggestions would be appreciated. Are there any tempermental areas on this tractor. Thanks in advance, Terry (tfringo@aol.com)

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Steve in N.J.

07-19-2003 08:07:56

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 Re: Questions about AC model B, plug type, timing. in reply to Terry, 07-18-2003 21:10:16  
Hi Terry,
We carry Autolite spark plugs in stock for the AC machines. We also build spark plug wire sets specifically for the different model AC machine's also. Drop us a line if ya need anything. We also have a catalog if interested. Drop us a line with your mailing address and we'll shoot one right out to ya. Steve/B&B Custom Circuits

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07-18-2003 22:57:32

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 Re: Questions about AC model B, plug type, timing. in reply to Terry, 07-18-2003 21:10:16  
Hi Terry,

Fairbanks Morse had some tooling issues and couldn't keep up with the demand that AC put on them during those early production years. They second sourced WICO to supply mags when Fairbanks fell short. WICO made good mags and they are vintage original.

You can get WICO points and condensors at NAPA and most tractor supply stores.

As for a replacement for AC-45 plugs, the Autolite 295 is that plug. You DO NOT want a resistor plug NOR resistive wires. You absolutly must have hard wire conductors or you'll wring your arm off trying to crank that tractor. You can usually get a universal wire set from a tractor supply store for as little as $8.95 and they work fine.

Timing is easy. Remove the mag and pull the #1 plug so it's just hanging in the hole by a thread or two. Crank the motor over till you hear the compression hissing past that loose plug. Now look in the flywheel timing hole in the left side of the bell housing (torque tube) and turn the fan backwards until you see the top dead center mark. This is not the FIRE mark. Now keep turning the fan backwards so that the magneto drive is horizontal.

Manually work the magneto so that the #3 hole has just fired and reinstall the mag so that it is leaning all the way over onto the block.

Crank it over to check that the mag is firing #1 plug when #1 cylinder is on compression stroke.

With the TDC mark visible in the side port hole, slowly rotate the mag forward until you hear the impulse snap and tighten it down.

With the mag set this way, it will compensate to fire on the FIRE mark once the motor gets running. You can check it with a timing light but it always works for me.

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07-19-2003 09:39:05

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 Re: Re: Questions about AC model B, plug type, tim in reply to Tyler(WA), 07-18-2003 22:57:32  
Tyler, I will have to try that loose spark plug trick. My girl friend gets mad at me when I make here hold her thumb over the #1 hole to find compression stroke. It is kind of hard to put your thumb over the hole and crank the engine. Of course if I rotate the mag until it fires on #1, and take it off, then put it back on the same way, it stays in time.

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07-19-2003 06:00:32

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 Re: Re: Questions about AC model B, plug type, tim in reply to Tyler(WA), 07-18-2003 22:57:32  
Outstanding. We can get something done now. It does have the resistor wires on it and resistor plugs. 2 days ago we put a new manifold on it because the old one roted through from the exhaust to the intake side. It also had a couple of holes in the side of it. The gas tank leaks when it is more than half full. He was lucky he didn't blow himself up. I will change everything out and see what happens. Is there any place that sells reproduction manuals for it. If you want a picture of it, let me know. Its a sad creature to look at. Terry

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07-18-2003 22:22:59

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 Re: Questions about AC model B, plug type, timing. in reply to Terry, 07-18-2003 21:10:16  
Hi Terry!
My B came to me 10 years ago with Autolite #295 plugs, and they work great. Points are Napa CS 1504, and condenser is napa FM 200. I have a FMX 4B3 magneto, so do not know about the Wico. I have replaced my points, condenser, and cap, but have never messed with anything in the gears. When I first bought the tractor, I found and old Allis mechanic, who is gone now, and he told me to take the cover off the mag and hand crank till it pointed to the 11:00 position. This is pointing to #1 on cap. Then I could take the mag off and work on it. Just do not crank it again, until you put the mag on. I have never messed with the gears in the mag. If it is not broke, I do not fix it. Your Wico is probably the same way. I guess if you did take it off and then rotate the engine, you would bring #1 piston up on TDC of compression stroke and rotate mag until it pointed to 11:00 position (#1 lug on cap), and put mag on. 11:00 position is you are sitting in the seat and looking at the mag. My tractor has run great for 10 years doing what the old mechanic told me. If you mess with the gears in the mag, that is a different story. You can rotate the mag a little after you put it back on, but I have either been really lucky, or it is not that critical to timing. Again, I do not have a Wico, so it may be different.

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07-19-2003 06:09:23

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 Re: Re: Questions about AC model B, plug type, tim in reply to Ken/Wa, 07-18-2003 22:22:59  
Thank you for the great comments. I will get something done with it. I have it running but I can tell the plugs are not consistantly firing. The spark looks good. It had 2 year old gas in it which was one of many problems. The intake is fixed. Now I need to get rid of the plugs and wires. The points look new. I would like to find a good used gas tank for it but that might be close to impossible. If any one has one or knows where one is for sale, let me know. Best regards, Terry

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Glenn in PA

07-19-2003 06:45:06

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 Re: Re: Re: Questions about AC model B, plug type, in reply to Terry, 07-19-2003 06:09:23  

Buy a POR 15 Gas Tank Sealer Kit! $27.00 + shipping. You can find the POR store online, just search for POR 15. Mine had the same problem with leaking, now it is like new. I had to put some black electrical tape ove 2 pin holes, then used JB weld to reinforce after it cured. (didn't have to, but I was just being cautious) If I did it again, I would take 1/2 the can of sealer and pour it in, then cap it. After the first coat cured, I would reseal with the second half of the can. ( the bottom of my tank was REALLY BAD) I can't say enough good about the stuff, just be sure to follow the directions and take your time. It saves the trouble of finding a new tank!

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