Magnetron

[rsnik]

I had this 10 HP running fine for a minute or two when I bought the 2010 Landlord before there was a loud bang and the spark plug blew taking all the threads out of the head. But it did seem to run and run well. PO said the kill wire is not connected to the ignition switch and you just grab the wire and ground it out to kill the engine. The kill wire was loose and just sticking out of the console.

Piston and valves look good, so I put a new head on it I came across.

Problem is when I removed the engine tin the coil says "this side out". Uh, oh, that means it's a Magnetron. I bought a Briggs engine manual which seems to identify it as a Type I Magnetron. However, the Briggs manual drawing of a Type I and Type II Magnetron show two pig tails with pan head terminals coming off the Magnetron. Here are two views of the Magnetron on my engine:

Just a spade terminal with two wires crimped into the female terminal connector that connects to the spade terminal. The second wire, to my recollection was just like the kill wire, flying around loose, connected to nothing. My question is, put simply, what do I do? I am thinking cut off the second wire and run the kill wire from the spade terminal on the Magnetron up to the ignition switch and that should work. I have read all the reading. With the Magnetron a magnet trips a relay which causes the coil to charge followed by a magnet which charges the coil followed by a magnet which trips a relay and grounds the coil, collapsing the field and sending the voltage to ground out through the spark plug wire where it grounds when it jumps the spark plug gap. I am assuming the second wire is not needed to ground the coil and is totally useless? Thanks. Oh yeah, one more question. The manual gives the spec for adjusting the Magnetron air gap as .010/.014. Does that mean when the engine is cold/hot or should you split the difference?

[RayS]

I see that it looks like it has a points cover. If it has a date code before the date in the picture posted it needs a magneto part number 298968. The flywheel would need to be repolarized to run correctly to use the magnetron or at least that has been my experince. I had one that would run but not correctly. I have also bought several tractors in the past where previous owner bought the magnetron ignition as a replacement and couldn`t get the motor to run correctly. I have three engines that I bought new that has the magnetron ignition and they have a kill switch at the top of the shroud. One of the wires goes to that switch and the other goes to a terminal on the exterior of the block and a kill wire from the ignition switch also goes to the exterior terminal. The exterior terminal is on the block where the points box was on the older engines. I would check the date code and make sure that it has the correct armature (coil).

[rsnik]

Thanks Ray, The PO was an eBay seller selling the tractor for his brother who got the tractor from the estate of a deceased co-worker (memo to self: not good idea to buy tractors this way sm02) I ran the tractor long enough before the plug blew to see that it ran, but running well is another story. Hopefully the deceased PO sent the flywheel to Briggs to have it repolarized, but I have no way of knowing that. The date code on the engine tin of the 243431 is 1967 (it's a 2010). There is a date code on the coil body of every Magnatron, on this one it is 3-1-90. I don't understand the date code 81080100. I don't see a number other than the 3-1-90 date code on the coil body of the Magnetron and I looked carefully more than once. Do you have any idea what kind of part #298968 is. It says "breaker ignition". A Magnetron that requires points sounds funny but maybe this one does. One mystery possibly solved is that the second wire probably goes to a second kill switch on the shroud. The first wire that goes to a terminal on the block before going to the kill switch I don't think is grounded to the block, I think the exterior terminal on the block is simply an insulated binder post to secure the wire enroute to it's final destination at the ignition switch. I leave the points installed and the points cover alone when I put in a points eliminator. If you remove the points or any of the machine screws in there oil leaks out like crazy. I just leave everything intact and remove the points wire. That may have been the case here. Thank you so much for your help. No sense putting the engine tin back on until I decide what to do. The safest bet would be to send the flywheel off to Briggs to see if it is repolarized and buy a new Magnetron coil as well. That would take a lot of time so I am open to suggestions big time.

[RayS]

code 81080100 81 is the year 08 is month 01 is the day 00 i believe is the plant it was manufactured in 298968 is a magneto that uses points and condensor. You are correct it is a insulated terminal. The manual has a typo error. here is a link that Brent wrote. http://simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=89069&SearchTerms=magnetron

[rsnik]

OK, I got what you mean, the date code on the engine tin. The first 2 numbers on the date code of my engine are 67. The way I am reading the link it sounds like there should not be a Magnetron that requires points and condenser (that would be kind of like an automatic transmission that can only be shifted with a clutch). This coil says "this side out" on one side and "cylinder side" on the other side. My understanding is that this means absolutely that this is a Magnetron. In your experience is there such a thing as a Magnetron that requires points and condenser to work? I can see where it might happen. Maybe an early Magnetron was designed to work off the points and condenser if the flywheel had not been repolarized. In terms of solving the mystery I think the date code on the Magnetron may be helpful. Turn a Magnetron upside down and it has a date code burned into to the plastic (I'll go out and take a pic, be right back) OK here it is:

Well, the date code is 1990. The 2010 was in the kind of extraordinary condition that looked like money was spent freely on it for it's entire life. I don't think the deceased PO would have put up with an engine that ran poorly since 1990; the overall look of the tractor strongly indicates a PO that ran a tight ship. Of course, I may have missed seeing that that second wire was connected to the wire which still comes out of the points box. The points and condenser still look to be in good, usable condition. I am tempted to assume the PO had the flywheel repolarized and that I just need to connect the kill wire to the ignition switch.

[powerking_one]

Jonathon, Here is an oldy-mouldy from the forum past..... http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=8770 Comrades, Well after seaching, and searching, and searching, I believe I have the answers to some of the (conflicting?) furvor on converting the old (pre-1980) cast iron singles(with a 2-pole coil and single magnet flywheel) to Magnetron ignition. Why some say it works, why some say it works without flywheel magnet re-polarization, but it starts harder/runs poorer now, and some say it plain doesn't work. My experiences cited are with the 394970 add-on Magnetron kit. For those of you that opted for the complete 398811 Magnetron coil assy, the plug wire is the correct length (I assume). Everything I've checked is via empircal methods including the use of a compass, DVM, timing light, and oscilloscope. My engine example is typical of others' discussions in this forum (model 243431 date code 1967). Fact: the magnet polarity is indeed reversed from other Briggs models the Magnetron module IS supposed to work on. I checked this on 3 different engines:130232, 191702, 90XXX? and their polarities are all NORTH(compass points SOUTH). Hence my 243431 magnet is SOUTH (compass points NORTH). The instructions state that it will NOT work unless it is installed on those CAST IRON or 2 CYLINDER engines "ORGINALLY EQUIPED" with the Magnetron ignition. This is true: A) the module ends up being on the RIGHT side of the coil (instead of LEFT). This position yields absolutely NO SPARK. IF you reverse the coil mounting 180 degrees, a few things change: A) now the spark plug wire is too short and has to be extended, B) you will have spark but at a 1/2 NORMAL VOTAGE LEVEL and at a much higher minimum RPM to achieve spark. Also, just as/more important, the ignition timing is SEVERELY OFF. Most L-head fixed timing air cooled engines should run about 19-22 degrees of advance. Now with the above condition, the Magnetron/coil is firing on the LEADING edge of the magnet instead of the TRAILING edge of it; hence we're adding 10+ degrees more advance! This explains a lot of the -hard starting- -backfiring- and (overheating?) problems some folks have reported. I verified all this with a timing light. If you move the coil mounting bracket all the way to the right, it still isn't enough retard to get the the timing in the correct ballpark (and you still have the reduced spark voltage condition). As for why the voltage is 1/2 now, it's because the Magnetron is firing too early (coil is only charged on the the "push" cycle of the leading edge magnet passing over. Normally, the points close(or open on some engines) when the magnet passes over the trailing "push to pull" side of the coil. Bottom line: without flywheel magnet re-polarization on these old girls, we have a totally MARGINAL ignition operating condition due to half the normal spark voltage and incorrect timing. Attached is a crude schematic I drew (stop laughing!), but shows the system. Now if I can just find somebody local to re-magnetize my flywheel. Hope this helps, Tom(PK)

[rsnik]

Hi Tom, Thank you for your considerable effort. This is one of those problems that you get when buying a tractor from a deceased PO. If the flywheel has been sent to Briggs and re-manufactured to work with the Magnetron coil I am all set. If not it wont run right. Briggs should have stamped something on the flywheel to indicate it had been re-manufactured to run with a Magnetron coil. BTW, if they did, give me a shout. I am still not clear, but pretty much think I only need to run a kill wire from the spade terminal on the coil to the ignition switch. I think the second wire joined to the female connector goes to an optional second kill switch on the engine shroud. This is an unusual situation because I only heard the engine run for about a minute after I bought the tractor before the spark plug blew out taking out the threads on the head. The seller was an eBay seller selling it for his brother who bought it from the estate of a deceased co-worker. A Magnetron will run, but not run well if the flywheel has not been re-polarized. I didn't hear it run long enough or drive the tractor to find out if it runs well. Oh well. So far I have one Simplicity that runs excellent and a growing graveyard of those that don't. A neighbor has a 3212V and may be interested in my chicken coop. If that works out gosh only knows what I am going to do with a 2010 consisting of "two halves and six boxes of parts" to quote Roy.

[powerking_one]

All you need to do is move a compass near the outer surface of the magnet. If it points SOUTH, it is the correct polarity for a Magnetron. I think Briggs did actually mark or color code the flywheels on late model CI singles with factory Magnetrons. The compass test is sure fire way to tell.

[rsnik]

Wow! Thanks Tom! Sadly I don't understand. Magnets, I think, have a north and south pole. Then there is the direction south, 180 degrees true magnetic, which points to the south pole of the earth. I think you are talking about determining the north/south orientation of the magnet in the flywheel. Lets say I am looking at the face of the flywheel like it was a clock with the center of the magnet on the rim at the top (call it 12 o'clock position). Should I move a compass near the outer surface of the magnet with the north of the compass pointing towards 2 o'clock (to the right) and see if the needle points back towards south which would the direction of 10 o'clock (to the left) on the flywheel? Or should I orient the north on the compass so it points toward 10 o'clock and see if the needle points south, which in this instance would be pointing towards 2 o'clock? Or am I totally off base and not getting the concept at all? :o) I will go out, do some experimenting and see what I come up with. Thanks very much!

[rsnik]

Well, here are the results of the compass test. The compass is a high quality, recent Davis Instruments hand held bearing compass. The first picture is holding the compass in the 10 o'clock position, to the left side of the flywheel:

The next picture shows the compass held at the 12 o'clock position:

The last picture shows holding the compass in the 2 o'clock position, to the right of center:

Well, it says south in every case. Is this good news? Thanks so much again. Jon

[B.Ikard]

I sent one of these flywheels back to Briggs for repolarization earlier this year. I was very pleasantly suprised with the speed and customer service-I was apprehensive about mailing the flywheel off to parts unknown likely to never see it again....got ot back in 7 days !! IMHO Magnetron conversion is the only way to go on these engines-maintenance and trouble free ignition system. You will need to center up your armature bracket per the Briggs manual.. All my tractors are converted 16's or OEM magnetron-yes even with starter generator systems. They start instantly and run perfectly. It was a painless experience and would not hesitate to send another one-all the details and address can be found with a search. Brent

[powerking_one]

Jon, It looks like you are one of the few to inherit one of the engines where the P.O. or shop person actually did the conversion "correctly". Tom(PK)

[rsnik]

Woo Hoo! I can finally put it back together. Thank you Tom, I owe you big time! Best, Jon