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Now that the little Neptune (1.7 hp) is running, it’s time to ponder upon it’s big brother, the opposed
twin 6 hp, once again. My attempts to convert the magneto to a Briggs and Stratton
coil failed miserably, so I bought a John Deere pony motor coil for “plan B”.
I would have to butcher the mag plate to even try this coil, and also whittle the lamination
down even more to fit the JD coil. If I had a spare mag plate I’d wouldn’t mind butchering one.
I’m thinking about plan “C”, just to see if this motor would run and be worthy of a new
$150 Maytag coil. š
Plan “C” would be some form of battery ignition.
I have a little 6 v battery for the Wisconsin outboard.
Would the Briggs and Stratton coil survive a 6 volt input to the primary?
Curious, how much voltage does the Stevens tester put out to the primary when testing a coil?
Thought about an automotive type coil, but that’s problematic being the Neptune is
a twin cylinder.
Thoughts on a workable battery ignition welcomed, so I can test run this outboard in my lifetime!
Thanks.
Prepare to be boarded!
Evinrude’s battery ignition racing motors ran on a 6 or 7- 1/2 volt Hot Shot battery. Of course you do have to remember to shut off the power when the motor isn’t running. If the points happen to be closed when at rest, it will run down the battery and overheat the coil. This is no problem with the Elto as the points only momentarily snap shut when the motor is running. Steve Woods runs his Elto’s on a length of PVC pipe with 4 “D” cells in it – it puts out 6 volts and goes many hours of running time over a week end. ., .
Evinrudeās battery ignition racing motors ran on a 6 or 7- 1/2 volt Hot Shot battery. Of course you do have to remember to shut off the power when the motor isnāt running. If the points happen to be closed when at rest, it will run down the battery and overheat the coil. This is no problem with the Elto as the points only momentarily snap shut when the motor is running. Steve Woods runs his Eltoās on a length of PVC pipe with 4 āDā cells in it ā it puts out 6 volts and goes many hours of running time over a week end. ., .
Garry, thanks for the input. I’m not sure how Evinrude racing coils stack up against B&S lawnmower coils, and the points being closed on the Neptune
for most of the crankshaft rotation, vs. the Evinrude’s points only closing to “fire”. Guess I wouldn’t be out much trying at this point.Prepare to be boarded!
Could you use a complete mag from a 4 hp? Given of course that the mag would be goodā¦and that the flywheel would workā¦
Richard, Excellent idea on the 4 hp mag plates.
I have two, and it looks like they have the same (troublesome)
coils. Not sure if the whole mag plate is interchangeable, and if so,
what flywheel would fit. I’d have to tear apart a running motor
to find out, and hopefully it would still be a running motor when
the experiment is over. š
Prepare to be boarded!
Iāve been following this thread and would also like to know if my twin (11B4) would run on a 6v buzz box. And 0.22 mfd condenser?
I think a buzz box would be problematic if the original points were used,
as those systems are designed for the contactor or points to only
close when firing. I suppose a contactor could be fabricated though,
instead of using the original points.If the B&S small engine coil would not withstand the 6v battery,
I suppose one could try an automotive type coil, mounted on the power head,
using the original points under the flywheel, but I’d have to
“Y” out of the coil secondary to have a spark plug wire to go to
each cylinder. Would that work?Prepare to be boarded!
On the idea of “battery ignition”, I found these two coils that would omit splicing a “Y”
in the spark plug wires on an automotive type coil.
One is for an Onan Opposed twin, the other 2005 era GM coil packs,
which one fellow adapted to his twin opposed lawn tractor.
I wonder how long running these coils before the battery ran out of “juice”?
Prepare to be boarded!
After shoveling, snowblowing, and plowing 10″ of wet heavy snow this morning,
I told myself I was going to stay inside the rest of the day (or month), but
boredom and curiosity got to me, so I went out to the garage to look
at the 4 hp OB35A 4 hp Magneto. Compared magneto diameters between
the 4 hp and 6 hp OB64A that needs a coil, and they were the same OD.
Off to a good start, so I tried exchanging flywheel nuts. 6 hp nut was too loose
on the 4 hp crank….. and of course, the 4 hp nut would not go on the 6 hp.
Figured this was going to be a “deal breaker”, and it would have different crankshaft
taper and or diameter, but not much to loose at this point, so I pulled the flywheel on the
4 hp and slid it on the 6 hp crankshaft…. it fits!
Then removed the mag plate off the 4hp and it fit right on the 6 hp crankcase boss,
no problem. Both mag plates are stamped Model 72A. The 6 hp flywheel even appears
that it will work with the 4 hp mag underneath.
The 4 hp Eisemann coil looked good (but I’ve never had this 4 hp running or worked on it yet)
so I checked it with the Ohm meter. Reading 7.6 K across the secondaries, and .2 K on the
primary, so I think it’s worth a “go”, but it needs new plug wires for sure.
If it does work, I’ll be minus a coil on the 4 hp for when the time comes, so I may still be
experimenting with battery ignition.P.S.- regarding the flywheel nuts, the small one is 7/16″ NF, and the the other,
between 7/16″ and 1/2″ NF. Is there such a bolt as a 15/32″ NF or something?Prepare to be boarded!
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