Thought I would relay an experience I had with the ignition setup on an old Mac 10-10 I've been working on. The saw would give a weak intermittent spark, would start and run poorly if at all, and sometimes kick back while trying to start it. I took it apart to inspect it, and see if it was points (usually easy fix) or solid state (good luck with parts).
First thing I noticed was that the flywheel/coil gap seemed excessive- it was, about twice what it should be. Strike one. The flywheel came off easy and showed it had points type ignition. They too looked to have an excessive gap, they did. Strike two. Then just on a hunch I measured the spark plug, you got it, excessive gap! Strike 3, flame out.
So, all three contributed to a poor spark, most of all the flywheel/coil gap. This is critical for a good spark, especially on older systems. The kickback was caused by the excessive points gap, this caused the points to open too early and advance the timing. This also causes poor coil saturation, another contributor to weak spark. The points were in really good shape, no pitting which would usually indicate some problem with the condenser. Did a light cleaning with emery cloth and put them back in.
Reset everything to a 10-20-30 setting. 10 thou flywheel, 20 thou points, and 30 thou spark plug. (Easy to remember). Put everything back together, nice fat spark, started 2nd pull and ran perfect.
So it's worth the time and effort to take it apart. The local shops didn't even want to touch the saw, I guess they thought it was a waste of their time, but in this case it turned a saw that would hardly run into something that was a pleasure to use.
So for a couple of hours of your labor and often zero money, old points ignition systems are well worth the effort. They have been giving us good running engines for decades before solid state, and just need a little tlc from time to time to keep it that way.
First thing I noticed was that the flywheel/coil gap seemed excessive- it was, about twice what it should be. Strike one. The flywheel came off easy and showed it had points type ignition. They too looked to have an excessive gap, they did. Strike two. Then just on a hunch I measured the spark plug, you got it, excessive gap! Strike 3, flame out.
So, all three contributed to a poor spark, most of all the flywheel/coil gap. This is critical for a good spark, especially on older systems. The kickback was caused by the excessive points gap, this caused the points to open too early and advance the timing. This also causes poor coil saturation, another contributor to weak spark. The points were in really good shape, no pitting which would usually indicate some problem with the condenser. Did a light cleaning with emery cloth and put them back in.
Reset everything to a 10-20-30 setting. 10 thou flywheel, 20 thou points, and 30 thou spark plug. (Easy to remember). Put everything back together, nice fat spark, started 2nd pull and ran perfect.
So it's worth the time and effort to take it apart. The local shops didn't even want to touch the saw, I guess they thought it was a waste of their time, but in this case it turned a saw that would hardly run into something that was a pleasure to use.
So for a couple of hours of your labor and often zero money, old points ignition systems are well worth the effort. They have been giving us good running engines for decades before solid state, and just need a little tlc from time to time to keep it that way.
