Model B mag question

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   Here's the newest of many questions to come regarding my 1945 Model B. I bought this as a non-runner, having a lot of faith in the seller's honesty. He no longer had the physical ability to climb onto the tractor, and it had sat for a number of years. He told me he started it once or so every year and decided to sell it after it would no longer start. The oil color backed up his story (it was frothy and the color of a coffee milkshake), like the engine had been started many times and never allowed to warm up.

Seller claimed no spark, and he was correct. This is a magneto model, and I found a shorted coil after a bit of work. I replaced that, after reading Rod in NH's instructions on timing the two gears correctly. I filed the points and set the gap. It gives a good enough jolt to cause some discomfort. I installed new plugs and made new copper core leads. The ungrateful B still won't start.

Should you be able to hear the impulse coupler snapping as the engine turns over? I can't. I had a friend stand right night to the mag and listen as I was turning it over. No clicking was heard. All my mag experience is with old Harleys that don't have impulse couplers. Could a stuck impulse coupler prevent the engine from starting? 

I appreciate any & all advice. Thanks.

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Scott in MA Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 25 Apr 2010 Points: 40	Post Options Post Reply Quote Scott in MA Report Post Thanks(0) Quote Reply Topic: Model B mag question Posted: 02 May 2010 at 7:59pm
	Here's the newest of many questions to come regarding my 1945 Model B. I bought this as a non-runner, having a lot of faith in the seller's honesty. He no longer had the physical ability to climb onto the tractor, and it had sat for a number of years. He told me he started it once or so every year and decided to sell it after it would no longer start. The oil color backed up his story (it was frothy and the color of a coffee milkshake), like the engine had been started many times and never allowed to warm up. Seller claimed no spark, and he was correct. This is a magneto model, and I found a shorted coil after a bit of work. I replaced that, after reading Rod in NH's instructions on timing the two gears correctly. I filed the points and set the gap. It gives a good enough jolt to cause some discomfort. I installed new plugs and made new copper core leads. The ungrateful B still won't start. Should you be able to hear the impulse coupler snapping as the engine turns over? I can't. I had a friend stand right night to the mag and listen as I was turning it over. No clicking was heard. All my mag experience is with old Harleys that don't have impulse couplers. Could a stuck impulse coupler prevent the engine from starting? I appreciate any & all advice. Thanks.

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morton(pa) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Lancaster, PA Points: 1234	Post Options Post Reply Quote morton(pa) Report Post Thanks(0) Quote Reply Posted: 02 May 2010 at 8:03pm
	If hand cranking, yes, you should be able to hear the impluse. It should be a rather loud click. Weather hand turning it or turning the tractor over with the hand crank, you should be able to hear it. However, if you are cranking it with a starter, there is a very good chance you can not hear it. I was told once by someone that the starter spins the mag faster and the impluse kicks out or something like that? I don't quite remember. But that is just what I was told. I don't know if it was true or not.

wjohn Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 19 Jan 2010 Location: KS Points: 2044	Post Options Post Reply Quote wjohn Report Post Thanks(0) Quote Reply Posted: 02 May 2010 at 8:10pm
	Morton's right. Even though I am pretty young and have good ears, I would think that nearly everybody should be able to hear the impulse coupler click if you're standing up front hand cranking it. Especially since proper technique has you stand on the same side of the tractor as the magneto; it's a fairly loud snap. I can definitely hear the one in my B when I turn it over. No idea about trying to hear it when using an electric starter though.
	1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45

steve(ill) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 11 Sep 2009 Location: illinois Points: 82705	Post Options Post Reply Quote steve(ill) Report Post Thanks(0) Quote Reply Posted: 02 May 2010 at 8:15pm
	pull 3-4 of the spark plugs out and put 2 spoonfulls of gas into each hole. Put the plugs back in and crank. If it starts and then stops, or fires several times, then quits--- you have a carb problem. If it still wont fire, you need to work on the mag, or time it.
	Like them all, but love the "B"s.

Cal Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 14 Sep 2009 Location: East Woodstock Points: 172	Post Options Post Reply Quote Cal Report Post Thanks(0) Quote Reply Posted: 02 May 2010 at 8:39pm
	If the impuse is not working it should still start with a tow, as that will spin the engine and also turn the engine fast enough to prime the oil pump. Cal in Ct

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5087	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 02 May 2010 at 9:18pm
	The pawls/dogs that catch on the stop pin to load the clock spring in the impulse can get rusted fast to where the little springs will not hold them out. If the clock spring is not broken or was taken apart and not wound correctly you can sometimes oil and move the pawls back and fourth and get them working without removing the drive causing you to have to rewind the clock spring. When one of the little pawl springs are broken the impulse will catch and load when clamped upright in a vise and not on the tractor. That can almost drive one nuts trying to figure out why it works in a vise off the tractor and will not work on the tractor. Seems it must to have worked in some manor for you to get a jolt.

Dave(inMA) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2398	Post Options Post Reply Quote Dave(inMA) Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 6:29am
	Scott, where in Massachusetts are you? Might be some help available!
	WC, CA, D14, WD45

DaveKamp Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Apr 2010 Location: LeClaire, Ia Points: 5816	Post Options Post Reply Quote DaveKamp Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 6:58am
	And the impulser mechanism is overridden by centrifugal force- this means you'll get the 'clack' only when it's turning slow, but not when turning fast. Using the electric starter CAN spin the engine fast enough for the impulser to be overridden, but at that speed, you shouldn't need the impulser to generate a sufficient spark. Judging the spark by comfort level really isn't indicative of proper mag operation- I had a big Hercules JXLD six that would generate a painful bite, and there'd be a spark, but not hot enough to do the job well. We've got a local mag guru that went through mine, changed a few parts out, put it on the mag-tester, adjusted it properly, and now it really bangs out a bolt of hot lightning. I'd say pull the mag off and take it to a shop, and while it's out, change the oil, dismantle and soak the carb good, drain the fuel tank, clean everything out good, reassemble, and about that time, your mag will be back, put it on, and give it another shot. Usually 'sitting tractor syndrome' is cured by oil change, carb soak, tank cleaning, and mag job.

Dusty MI Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 13 Sep 2009 Location: Charlotte, Mi Points: 5058	Post Options Post Reply Quote Dusty MI Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 7:02am
	Caution, if the impulse is stuck in the run position the engine in MUCH more likely to kick. Dusty
	917 H, '48 G, '65 D-10 series III "Allis Express"

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5087	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 9:57am
	Dusty, If the pawls are stuck in the ("run position") you can not crank it by hand fast enough to make a spark.

Scott in MA Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 25 Apr 2010 Points: 40	Post Options Post Reply Quote Scott in MA Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 10:14am
	Dave - I'm in East Longmeadow (next to Springfield). Dave Kamp - I'm pretty confident in the mag work I did, except for the impulse coupler (never took the mag off the tractor). I've rebuilt a few F-M mags for motorcycles but never saw an impulse coupler up close and in person (bike mags rely on a healthy right leg instead of the coupler). The only thing I didn't do to the mag, besides inspect the coupler, was get the magnets recharged. All the copper inside was pretty clean, so I shined it all up with some 400 grit. The tank had been drained when I got it and in support of the seller's story that it was relatively new, looked pretty clean inside. I haven't looked inside the carb (other than to free a stuck choke). Steve suggested putting some gas into each cylinder to eliminate either the carb or mag as the culprit. I used starting spray, which I imagine has the same effect. The ether came out of the exhaust pipe in puffs - just like exhaust - except it was unburned. Either my battery is tired, my starter motor needs help, or this thing is 65 years old - because it doesn't spin all that fast with the e-start. Someone metioned a pull start earlier, and that would be nice but I don't have the room. Thanks again for the responses.

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11891	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 03 May 2010 at 11:20am
	First thing you shouldn't do is file points. In a pinch out in the field to get the engine running again is one thing, but filing the points removes the cad plating on them to keep corrosion down. Once this is removed, the points will oxidize every time it sits for a few days. Always use a tuner cleaner or Brakekleen to clean off the oxidation on the points. A little spritz goes a long way. As Dick L. mentioned, if the pawls are rusty and hanging up on the impulse coupler, they won't come out to catch the stop. It should click even with the starter turning it over providing you're using a 6V Battery. If using a 12V Battery, it is possible to spin the engine over faster than the Mag's impulse can engage, which in some cases makes for hard starting. I would install a new set of points and condenser and check to see if it lights up with a little gas or a spritz of ether. The contacts might just be the only problem. Go to the easy stuff first... HTH Steve@B&B