Timing bouncing all around, a20a1 , weber 32/36 carb, 1988 honda accord

[Steve0623]

Trying to set my timing, but the timing marks are jumping all around.

Tried this with the vacuum advance on and off and they're still bouncing. Any ideas?

Also when I plug in the advance (the close one, not for cold starting). it does advance the timing, but it still jumps all around.

[Dr_Snooz]

If you haven't done a tune up in awhile, that can cause erratic sparks. If that checks out, start looking for mechanical anomalies in your distributor, like a bad rotor bearing that makes the shaft slop around.

[cygnus x-1]

Look for sloppy distributor parts as Snooz said and also make sure the timing belt isn't loose.


C|

[g.frost]

Loose timing belt tensioner is my first thought.

[2oodoor]

Look at the inductive pick up on the timing light, is it closed on the spark wire well , also swap spark wire with one that reaches, still use #1 for the pick up but rule out the wire breaking down and being erratic for the light pick up.