Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

littlemarv

Converting to Magnetron

Recommended Posts

littlemarv

Does Briggs still repolarize flywheels so you can install a Magnetron coil? The engine I'm thinking of doing it to is a 302431.  Can this model even be converted? I googled it, it appears that years ago they even did it for free, you just had to ship it. But then I found a post that said they stopped doing it, and I haven't found anything newer to confirm or  deny it. Anybody done one lately?

 

Thanks

Share this post


Link to post
Share on other sites
MARK (LI)

I know that if they found a problem with your flywheel like a crack  while they had it that they would not return it I remember Tarly had a video about doing the job by turning the coil around...here is the video that I think it is

 

Share this post


Link to post
Share on other sites
littlemarv

After watching the video, I'm a little confused. I thought a magnetron flywheel had a separate notch to collapse the field, instead of points. So how does reversing the polarity of the magnets, or bolting the coil on backwards, work? Are we talking about two different things here?

Share this post


Link to post
Share on other sites
TimJr

I don't fully understand how just flipping the coil would work, but I have heard other people mention doing it.  I would think the timing would be off since the trigger is on one end of the coil assembly - right?

Also - the spark plug lead may or may not be long enough since it would technically be routed wrong with the coil on the wrong way.

The polarity of the flywheel magnets is one of 2 ways S-N-S and N-S-N.   I can't remember which way for points and magnetron on the iron engines.  The aluminum engines all used the same polarity compatible with Magnetron.

Briggs used to have a small tool that would indicate the polarity on flywheels.  It has a little letters that flip when you pass it over the magnet and it tells you the polarity.  Long obsolete - would love to find another one.

Have it repolarized and get an OEM Magnetron - best money you will spend on that engine.  I have done it to a couple of them over the years.  I gave my dad a later Magnetron flywheel to put on his 7016 engine - tired of doing points - anyway, he inadvertantly bolted the new Magnetron coil on upside down (despite it being labled).  He couldn't get it to run and was really frustrated.  So I had him pull the engine back out.  He pulled the shroud off while I was there and the first thing I saw was the upside down coil.  Flipped it and it has run great since........

Share this post


Link to post
Share on other sites
Bill725
1 hour ago, littlemarv said:

Have any contact info? Isn't the place in Menomonie Falls?

Menomonee Falls Distribution Center

W148 N9121 Patrita Drive

Menomonee Falls, WI 53051-2272

Dock #23

Share this post


Link to post
Share on other sites
MARK (LI)
17 hours ago, TimJr said:

Have it repolarized and get an OEM Magnetron - best money you will spend on that engine.  I have done it to a couple of them over the years.  I gave my dad a later Magnetron flywheel to put on his 7016 engine - tired of doing points - anyway, he inadvertantly bolted the new Magnetron coil on upside down (despite it being labled).  He couldn't get it to run and was really frustrated.  So I had him pull the engine back out.  He pulled the shroud off while I was there and the first thing I saw was the upside down coil.  Flipped it and it has run great since........

Timjr....when you say that your father was through with dealing with  points.....how often did the points become a problem?...was he using the machine a lot?...I have had a problem here and there over the years with points, but not so much that I got tired of them...although I think that going electronic is well worth the small cost and the effort...I don;t have the experience that most of you guys on here seem to have, so I am just curious ...I hope you don't think I am questioning or challenging you....Mark

Share this post


Link to post
Share on other sites
TimJr

Points were getting pitted and then it would run poor.  Unsure if it was cheap Chinese materials or problems with cheap Chinese condensers.  A set of points and condenser was running about $30-35 or so a few years ago, and a Magnetron was only about $55.00.  After doing points 2 summers in a row, ditched them.

You're good - good questions.  I don't know for sure how many hours - it was a 7016 with 48" deck that mowed a bit over an acre, probably every 5 days unless it got dry out.  Plowed snow on probably a total of 400' of driveway - one tended to get drifted and would require some work at times.

Share this post


Link to post
Share on other sites
Chris727

Kind of wondering if the need for polarization has changed since Briggs changed vendors for coils several years ago. I believe the old style magnetrons that we are used to are no longer offered through B&S. The coils are now Chinese and look entirely different. I have read that there was no requirement for re polarization with this style of solid state coil but could be misinformation. Would like to verify that. 

 

 

Share this post


Link to post
Share on other sites
Tom45
I sent a request to Briggs about the Magnetron conversion and received the following reply today (11/26/2019).
Hello Tom,
Thank you for your inquiry about repolarization. You will need to ship your flywheel to the address below. There is no cost to get your flywheel polarized, but there is no time frame on when it may be complete.  

Menomonee Falls Distribution Center

INBOUND DOCKS 1-13

N83W12529 OLD ORCHARD ROAD

MENOMONEE FALLS WISCONSIN 53051E

 

Please keep in mind, we CANNOT return ship to a PO BOX (we need an actual address to ship to).

If you have any further questions, feel free to update this e-mail, or call our engine Customer Support at 800-444-7774, M-F 8-5PM CST.

Repolarizing of the flywheel would depend on the date code/date of manufacture of the engine (you also need to already have a Magnetron ignition kit 394970). To determine the date code, look at the engine’s STAMPED numbers:

Format of the date code is as follows

YYMMDDxx In the above example the date code is 061005 (October 05, 2006)

Please verify the engine Date Code. If the first 2 numbers in the Code are 81 or less, then you likely need to have your flywheel repolarized. NOT getting your flywheel repolarized, yet adding the ignition kit 394970 will cause a problem with the ignition/spark. The electronic ignition does not work well in conjunction with the existing polarity in these older engines’ flywheels. 

Typically this happens on older (1981 and older) horizontal shaft cast iron engines with model numbers beginning in 23, 24, 30 and 32.

Keep in mind, the electronic Magnetron module kit will NOT fit: 

  • All Briggs & Stratton aluminum engines built before 1963. These engines use three-legged armatures (see pic for example);

  • All Briggs & Stratton engines, except those originally equipped with magnetron ignitions, which were built after August 1, 1981. 

  • All twin-cylinder Briggs & Stratton engines, except those originally equipped with Magnetron ignitions, which were built after August 1, 1981. 

If you have a horizontal shaft cast iron engine with model numbers beginning in 23, 24, 30 and 32 and wish to install an ignition kit, we will re-polarize your flywheel and send it back to you, free of charge.

When shipping your flywheel, package it properly (we have received several of these already broken from shipment because they were not packaged properly), with a short note describing what you need, the Model, Type and Code of the engine, and a return address. 

Sincerely, 

Cheryl

Briggs & Stratton Customer Support

PLEASE NOTE: In order to locate and answer your concerns as quickly as possible, always include a copy of your original message (or prior correspondence) and do not change the subject line when replying to this e-mail.

------------------- Original Message -------------------
From: ;
Received: Tue Nov 26 2019 07:28:09 GMT-0700 (Mountain Standard Time)
To: Tom;
Subject: Other
Your Request:
-----------------------------------------------
I am rebuilding a 10 hp Briggs 243431 0123-01 and would like to update the ignition. Do you still offer the Magnetron conversion? Is it still necessary to repolarize the flywheel and do you still do that?
Thanks
  • Like 3

Share this post


Link to post
Share on other sites
bud119195
13 hours ago, BLT said:

Todd Bader @bud119195 has had success just wiring in a Nova II electronic module. Maybe he can 'chime in'  more.

Also I wired in a Mega-Fire , kept points and eliminated condenser..

5dd40390bfba7_MegaFireWithPointsBLT.jpg.a4e02b0acdf6972452b23beccf2cd7aa.jpg

 

Yes I have wired the Nova II Ignitions,have probably wired them on 15 engines,dating back to a 1961 7hp horizontal briggs,never once have I polarized a flywheel 

Share this post


Link to post
Share on other sites
Bill725
7 hours ago, bud119195 said:

Yes I have wired the Nova II Ignitions,have probably wired them on 15 engines,dating back to a 1961 7hp horizontal briggs,never once have I polarized a flywheel 

My understanding is: 1) the Magnetron is a B&S electronic ignition armature which replaces the original armature, points and condenser and reguires repolarization of the flywheel magnets. The Nova II is an aftermarket electronic ignition which replaces the points and condensor only and does not require repolarization of the flywheel because it uses the original armature.

  • Like 1

Share this post


Link to post
Share on other sites
Bill725
17 hours ago, Tom45 said:

I am rebuilding a 10 hp Briggs 243431 0123-01 and would like to update the ignition. Do you still offer the Magnetron conversion?

FYI, according to: 1) the B&S website and 2) the 2002 B&S Genuine Parts Catalog, the correct B&S Magnetron Ignition Armature is P/N 698811, not P/N 394970. Also, I have installed (2) of these, one into a 10HP/243431 and a 16HP/326431.

FYI, the B&S armature for points and condensor ignition armature is P/N 298968.

Share this post


Link to post
Share on other sites
wwbragg

Murphy's Law strictly stipulates that: "Nothing is as simple as it seems".  The 298968 coil is the coil for 30 cube motors (with a breaker point ignition system) and 32 cub motors (with a breaker point ignition system) BEFORE date code 81080100.  After that date, the proper coil for the 32 cube motor (with a breaker point ignition system)  is 398811. The difference in date codes coincides with Zippos's comment (see above) about two different flywheel polarities and would also explain why the flywheel with the reversed polarity would work if you have the wrong coil but mount it backwards. (see Taryl's video - - - just skip over the stupid part.)

698811???   I have been wrong before and have no fear of admitting it, but I think 698811 is an air breather cover.  As for that 394970, There is one on ebay for $12 but it doesn't even look like a coil.  The ebay sellers call it an "electronic ignition kit."  I'm tempted to buy one just to see what is going on.

I found a couple of brand new, in boxes, 298986 coils in the box of parts that came with one of my tractor purchases.  I'm going to put one on my 300421 along with a Nova II and will let you know

Edited by wwbragg

Share this post


Link to post
Share on other sites
Tom45

The Briggs parts list for the later 10hp engines shows magnetron coil 398811.  I believe Briggs gave a wrong and obsolete part number in their previous answer.  

Share this post


Link to post
Share on other sites
littlemarv

Thanks for all the help. I googled 394970, comes up as a kit, I even found a PDF on installation. I can probably pick one of the kits up locally, and I'm going to have the flywheel off anyways. I'm going to give it a whirl.

Share this post


Link to post
Share on other sites
wwbragg
1 hour ago, littlemarv said:

I'm going to give it a whirl

The description of the 394970 on jacks small engines says, "Replaces points and condenser. To retrofit Most 2 legged ignition Armatures w/Breaker Points . . . "  I interpret that to mean it functions like the Nova II ignition module only the Nova II is a more compact.  Like the Nova II, the 394970 bypasses the points and condenser using the original coil.  Many on this site have proclaimed the Nova II's performance.  I'll find out soon.

Edited by wwbragg
expanded

Share this post


Link to post
Share on other sites
littlemarv

I think the Nova II replaces points and condenser. Uses the original coil. A Magnetron does it all in the coil. No points or condenser needed, you just repolarize the flywheel, install the Magnetron coil, and hook the kill wire to the coil.

Share this post


Link to post
Share on other sites
littlefan

The 394970 is a kit briggs first offered in the early 80s the do work on any single cylinder aluminum engine but are not  for the cast iron blocks. They can be used if flywheel is repolarized. I work at b&s dealer at the time and tried this kit on a lot of engines.

Share this post


Link to post
Share on other sites
TimJr

OK - the 394970 was a factory upgrade for aluminum engines to get rid of the points.  You added that little kit to your original coil and you essentially converted it to a Magnetron.  Just leave the points in place if you want, or install the little plug that you put in the point plunger hole. If you had an engine that was oiling down the points, plugging the hole was necessary.  Then just unhook the kill wire from the points.

http://www.briggsandstratton.com/~/media/Frequently Asked Questions/Engine/PDFs/magnetron_retro_fit_ms7794.pdf

The modern aluminum engines with 2 bolt coils all had the same flywheel polarity.  You could either add this kit, or swap on a complete OEM Magnetron coil to get rid of points.

The cast iron engines used 2 different polarity patterns.  One pattern for engines built with points, and a different pattern that matched the aluminum engines when they changed to factory Magnetron.

I still don't understand how flipping a coil gets an engine to run correctly.  The polarity pattern on the flywheel didn't change.  Also, I am pretty sure that even on the factory Magnetron coils, the pick up module/trigger is located off center to one side.  See the above conversion instructions.  So, if you flip a coil over, you flip the trigger to the opposite side of center of the coil, altering the timing.  If I am picturing things correctly, that would result in the trigger being on the "retarded" side of things.  The trigger should be at the leading side of the coil, not the trailing side.  Easy to point to, hard to put into words. 

So in my opinion, even if it runs - you did it wrong.  Send out your flywheel and do it right.

Edited by TimJr
added info

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×