OT: 1971 Briggs and Stratton Ignition

[Hec In Omaha]

Howdy all! I hope everyone has had a great Christmas!

I am working on a 1971 Montgomery Wards Snowblower. It was made by Gilson Brothers and branded Mongomery Ward. It has an 8 HP horizontal shaft engine on it. This thing is a TANK! It had no spark when I got it So I went to the mower shop and the guy sells me a coil with a built in Magnatron. This coil was supposed to replace the old coil, points and condenser. "Just bolt it on and set the flywheel gap to .10" (Business Card Thickness) and connect the grounding wire to kill switch and your off!", the salesman says. Right? Wrong! After the installation the coil would produce a very weak spark. When I say weak I mean the spark is not visable at all but I get the shock sensation in my hand. So I took the coil back to the mower shop and he gave me a couple of used ones to try incase the new one was bad. Same results. Then I installed new points and condenser and she fired on the 2nd pull. My question is this, Why didn't the coil of a more modern 8 HP motor work on mine? Is there a difference in the flywheels?

I figured somebody on this forum has the answer.

Thanks in advance! And have a Happy New Year!
 

[teddy52food]

Magnets are different in the flywheel. They have to be matched up to work.
 

[Hec In Omaha]

teddy52food,

Thanks for the response. I have found some posts that say you have to repolarize the flywheel magnet to make it work.

Hec
 

[JMOR]

[Jubilee85(VA)]

not sure I understand "repolarize the flywheel magnet "

It is a permanent magnet? all the B&S flywheels of that era are/were magnets placed in the flywheel - so you aint gonna fix that ! I too think .10 is a weee bit big!!! When I set the coil, I would take a dollar bill and fold it once and slide it in,rotate and put bill back in pocket! I suggest you do that too.
 

[old]

To re-polarize a magnet would be like turning it upside down. I have in fact taken the newer type mag with the built in electronic ignitions and used them many times. The gap you where given sounds way to much to me. When I set them I use a piece of plastic from one of then hard to open pack you get parts etc in to set the air gap. Our I buy one of those add on chips for around $15 that you simple put in place of the points. I have an old Murry lawn tractor that the deck has long since fell off of that I used one of those chips and and it ran the last time I tried to start it. It is dated 1967 by the way
 

[McBride]

I have use many of them with no problems.
That gap sounds too big.
I think mine came with a piece of paper to set the gap.
Same flywheel is used for either. You don't have to to anything with the magnets.

Put a piece of printer paper between the new unit and the flywheel and tighten it down and then remove paper and give it a try. Make sure the wire coming from it is not grounded.
 

[Jason S.]

Per the Briggs shop manual the air gap is .010 to .014. It also states that the flywheel but turn at 350 rpm"s minimum to get the magnetron to fire. I worked in small engine for around 10 years and once I did come across a briggs and stratton flywheel that had a weak magnet. Only one time did I ever have that happen. It had very little spark and nothing would change it. I swapped flywheels and changed nothing else and it had the good purple spark.