No spark
Posted: Mon Sep 04, 2023 5:08 pm
I’ve rebuilt a 1966 Century Plus and am having trouble getting it to spark. I will give some relevant info and then ask some questions.
The old ignition coil (Villiers M1634E) was shorted internally, so I replaced it with an M1361 which seems to be a given substitution if you make up some spacers to allow for it’s shorter length.
The condenser was replaced with a new one, and the original points were cleaned up and re-used.
The magnets in the magneto rotor seem weak, a screwdriver will attach to them, but it’s not ‘snappy’.
When I pull start the motor with the spark plug out and grounded there is no spark, but if I hold it in my hand and keep the plug grounded I get a little kick(!). So it’s working, but not enough to make a spark that can jump the plug gap.
Question 1 - what is the easiest/cheapest/best way of making the magnets stronger.
Question 2 - what is an acceptable gap between the coil holders and the magnets (on a briggs and stratton it’s 0.02”)? As i have at least double that.
Question 3 - is it usual that the points are open for most of a crank rotation and close only for about 40 degrees? Normally (on a single cylinder engine) they would be closed for most of the rotation and only open for a bit.
Feedback and comments welcome, thank you, Paul
The old ignition coil (Villiers M1634E) was shorted internally, so I replaced it with an M1361 which seems to be a given substitution if you make up some spacers to allow for it’s shorter length.
The condenser was replaced with a new one, and the original points were cleaned up and re-used.
The magnets in the magneto rotor seem weak, a screwdriver will attach to them, but it’s not ‘snappy’.
When I pull start the motor with the spark plug out and grounded there is no spark, but if I hold it in my hand and keep the plug grounded I get a little kick(!). So it’s working, but not enough to make a spark that can jump the plug gap.
Question 1 - what is the easiest/cheapest/best way of making the magnets stronger.
Question 2 - what is an acceptable gap between the coil holders and the magnets (on a briggs and stratton it’s 0.02”)? As i have at least double that.
Question 3 - is it usual that the points are open for most of a crank rotation and close only for about 40 degrees? Normally (on a single cylinder engine) they would be closed for most of the rotation and only open for a bit.
Feedback and comments welcome, thank you, Paul