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MisterB

Ignitions - Points vs Electronic?

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MisterB
I know this is probably a question that has been asked and answered before, but I couldn't find anything by searching through the forums here. I have a `78 Simplicity Baron with a 14hp B&S engine model #326437. I replaced the points in it this summer as well as the remaining routine maintenance items (plug, oil) and lubricated according to the owners manual. A few weeks ago while mowing, it just stopped running and I have been unable to get it started since. I'm wondering if the points/condensor might have gone bad which begs the question - should I replace the points/cond again or convert to electronic? Is this even possible? I've seen the kits available for the older engines but they are listed as being for older 2-11hp. engines so I'm wondering if they'll work in my 14hp? I have to do something soon since winter is coming quickly this year and I'll need my snowblower shortly. Thanks in advance for any input. KB

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RayS

Put one of these kits in it. You will never be sorry. http://cgi.ebay.com/Electronic-Transistorized-Ignition-Module_W0QQitemZ7725932423QQcategoryZ79670QQssPageNameZWD1VQQrdZ1QQcmdZViewItem

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MisterB
Thanks for the quick response! Will this work in my old engine? I know there is a limit to the term "universal"... On a different note: I appreciate the help I've always gotten here. This problem served to remind me of the benefits this club has to offer. Proudly, I've finally become a dues paying member! Thanks again, KB

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dhardin
From what i understand, and I am not a expert on these units all though i have one working on a tractor right now. It is my understanding. This unit just electricly delays the spark generated from the coil every revolution. One on the down stroke after the compression of gas in the cylinder, (firing the gas) and another time in the exost stroke, or every revalution of the flywheel. This unit dose not worry about the timing of the vales. It fires every revalution, one need 1/2 the time. The only tricky part is the slight delay of the voltage from the coil it lets the spark plug to fire after the pistion is past top dead center. In short this unit grounds the voltage of the coil till the cyilinder is ready to fire and twice as much as need (every revolution). Taking it que from the passing of the magnet on the flywheel only. Intensity, well lets say it gives all the coil voltage has after the magnet has pass. With a poits system the high voltage generated by the charged coils had to be condensed at the poins to controll the burning or jumping to ground of the moving parts. (hence the potential for problems) And is only forwarded to the spark plug when the poins are together. This unit acts as a ground switch till the magnet has just passed the coil, (like 2 to 5 degrees) and ready to fire. In short it waits a few milliseconds after its fully charging has compleated and then un grounds the coil.

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B.Ikard
I don't have ignition problems with my Briggs but I'd be interested to learn how this module knows when to "fire" the coil. Is the coil/armature located in relation to flywheel by Briggs engineers so maximum magnetic field strength/saturation point occurs at 18-20 degrees BTDC? Ike

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dhardin
All good questions. Ronald i think the module let the energy created by the flywheel passing, fire the plug. The electronic module is sort of a stop and go swich, with a timed delay. B.Ikard i was told by someone that talked like he knew... The first series of the electronic moduals took a lot o RPMs to get it calbrated to the proper time to fire. And i think they fires a series of busts of the coil voltage. But the newer versions moduls dont seem to have that problem. Rember this unit is wired into the primary winding of the coil or in line with the shut off switch. And it is grounding the system till it time to fire. How dose it know. he** if I know.... Its a smart little thing. It must sence the advancing magnet and ground off the coil so it wont fire in advance, causing a back fireing. the wait a given amout of time in milliseconds and opens the coil to fire after TBC. Seveal factor are inportant to aid in these units to work well. (1 very close air gap of the coil. My kit come with a nylar strip to set the air gap. (2 a strong coil (3 a proper set spark pluge gap. a gage also provides with my modular kit. Thers are two eclectonc moduals out today, one for single cylinders (green units) and one for twins (red units). For $15 its one heck of a little gaget.

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B.Ikard
I have wondered since last night so I got re freshed by my old brown cover "good" Briggs repair manuals published in 1979 that has a well written section on theory of operation. The operation of magneto ignition systems is based on opening the points the instant the opposing magnet reaches the armature-this induces voltage to the secondary windings of the coil and fires the spark plug. The field collapses due to reverse polarity of the south (or north) magnet as it travels by the armature, and when the coil/armature ground is removed the plug sparks. I'd say the module has a zener diode or transistor that "biases" when polarity is reversed or has some other solid state device that opens the path to ground when reverse polarity is sensed. Drink deep at the fountain of knowledge,right? :) Ike

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MisterB
Is there an advantage in using points with an external coil over the aftermarket electronic points replacement module which apparently MUST be used with the internal coil? Any downside to this? I purchased a tester to check for spark since I can't get the engine to fire and it does indicate a spark but the light is more dim/orange. I'm wondering if the coil might be the problem. Is it normal for the internal coil to just weaken rather than fail altogether? If the internal coil is weak, it seemed to be better to use an external coil which I would think to produce a hotter spark but requires additional modifications which I am mechanically savvy enough to make. I don't think I have the expertise to remove the engine and flyheel to get to the internal coil. If I did, perhaps the magnetron might be a good route to take, provided I can get the flywheel re-polarized? What is the concensus here? Am I off base? KB

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RayS
You don`t have to remove the flywheel to replace the orignal magneto, but you do have to remove the engine. The job should take only a hour to a hour and a half at most. You will only need to remove 4 bolts at the base of the engine and 2 at the drive shaft.

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dhardin
MisterB to your original problem of having replaced parts and later stoped running, A week coil can get hot and fail, or just go bad. Not real common but i have seen it happen. Usueally if it cools down some it will have spark again. I really dont feel the coil is your problem. From my experence and from what you have told us. 1. Double check the plug. or try another plug. 2. Check the kill switch/wiring. 3. If your have a good meter you might check the resistence in the coil itself. Allways do the simple stuff first. For about 20 bucks and less than 3 mins, a wire cuter and a screw driver, you will know if its the poinst and condencer, and or if the coil is week. Try the electronic modual after you have check the basics.

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MisterB
So, I'm starting with the easy stuff... While I know it isn't the root cause, the battery is several years old so I replaced it as well as the cables - using nice new 2ga cables which I know is probaly overkill for this application but they were just slightly more expensive than the original 4ga cables. While I was at it I replaced the spark plug, carefully checking the gap before installation. No luck getting it started thus far. Thinking ahead, I picked up a replacement set of points and a condenser and I'll put those in tomorrow. One question: what exactly does the condenser do?

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HubbardRA
The condenser stabilies the arc across the points when they open. An engine will run without a condenser, but the firing will be erratic. Install the condenser, and it will smooth out and run great.

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MisterB
So, with that in mind are condensers made specific to the application or are they generic in function? Would an automotive type work just as well or perhaps better? If I find that the coil has gone bad and I decide to do the conversion to battery ignition, will the condenser I have now work or do I need something "bigger"?

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Roy
Almost any condenser that physically fits with work. But, the condenser (capacitor) size (in microfarads) must be correct for the application. Sized properly the points last a long time. Too small or too large and the points will pit on one side or the other. Maybe Al Eden can offer some guidance related to properly sizing the condenser.

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GWGAllisfan
wouldn't the size of the points need to be related to the strength of the coil? That is a "hotter" Coil would need a bigger condenser for the same point life?

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MisterB
quote:
1. Double check the plug. or try another plug. 2. Check the kill switch/wiring. 3. If your have a good meter you might check the resistence in the coil itself. Allways do the simple stuff first. For about 20 bucks and less than 3 mins, a wire cuter and a screw driver, you will know if its the poinst and condencer, and or if the coil is week. Try the electronic modual after you have check the basics.
Ok, so following the logical advice provided - I replaced the points and condenser today. After a few tries she finally fired up and is running fine! I found it harder to start that usual, but with the flooded carb I guess it's to be expected. What a relief... A few tweaks on the carb adustment screws and I'm back in business. On an related note - anyone know where I can find the carb shield for this tractor? I got one years ago when I got the snowblower and now I cannot seem to find the darn thing.

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