Killer2600
Forum Apprentice
but it does turn on after passing that mark and alot earlier than full advance.
You'll have to clarify. When the crank is rotating clockwise, the test light comes on at the full advance mark (when the rotor is held fully advanced), goes off some degrees later, and comes back on again before coming back around to the full advance mark (again the rotor is held fully advanced)? I presume when it comes on unexpectedly that it goes off before you arrive back at the full advance mark, where it comes on again. Would this additional turn on happen to occur 180? from the initial full advance mark (rotor held fully advanced)? If that's the case you're picking up the alternate coil's sequence which you shouldn't.
Make sure both coils fire independently and not simultaneously by watching plugs 3 and 4 while rotating the crank. If they fire independent of one another then try using an incandescent test light instead of an LED test light. LED test lights can be very sensitive and trigger even without a lot of power.
If you don't have access to a incandescent test light and have confirmed that the coils are firing independently, verifying that plug #4 sparks when the 1-4 timing mark hits the marker combined with your previous test light adjustments is sufficient to know timing is correct.
Tech tip: You can make an incandescent test light from an incandescent automotive bulb. Such a test light would work fine for this kind of work.
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