Too much timing???

crackedback said
Are you picking the RPM to observe total or are you revving it up until it stops advancing?

I'd try another distributor in the car to see if it has the same "adding timing" issue.

I use drill bit shanks of appropriate sizing to set mallory style advance distributors. I noticed that the stepped keys aren't always accurate.
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That's where it stops. It used to be all in by 2500 and stay there. Now at 2500 its right where it should be but as I get to 3000 it starts to move up and stops moving at 3500. I don't have an extra distributor around so was trying to narrow it down before I went out and bought one.