Converting a B&S
engine to Pointless Ignition
Turns out, it's EASY!
The points on this 8hp tiller were shot, and I had plenty of late
(after 1982) model B&S coils in the junk box. So I decided to
convert. This process ALSO works for most any B&S
points-fired lawnmower engine you might find.
Underneath the cover it looks like this. One of the nice thing
about converting is that you don't even have to pull the
flywheel. Actually, you should leave the points in there because
the point arm holds in the activation pushrod. Without the points
arm, the pushrod will push out and the engine will leak oil.
There are two wires going to the points, clip them up by the
coil. The point wire is moot, the wire to the shorting switch on
the throttle (if there is one) will need to be connected to the new
coil.
Here's the old coil on the right, and a "new" (had a "86 01" build
date) on the left. See the ignitor sensor?
If you're replacing a lawnmower with a lawnmower, it should be a bolt
on. Since I was putting a 3.5hp coil on a 8hp engine, I had to
grind the diameter of the coil arms to match the larger diameter.
When you grind (or file) the arms, CLAMP the laminations together
before grinding! Otherwise, they will spread like an old paint
brush!
Ask me how I know.......
See the spade lug out the back of the coil? That's where the
grounding wire goes to shut off the engine.
Here it is, back together and ready to have the coil screws
tightened. Notice the light cardboard spacer to take care of the
spacing.
Grounding wire goes out the back and to the shutoff switch.
Finish bolting it back together, and never worry about points again.
It works great with old lawnmowers with no spark because of the points,
and if you have a spare coil is a whole lot more effective than messing
with points.
Does it work with Tecumsehs? I don't know.