I agree with Mike B that timing could be your problem. It almost sounds to me like your centrifugal advance is not working. Your centrifugal advance bumps up the timing while the vacuum retards it. If your centrifugal advance has broken springs, it will not advance and your vacuum will retard it. Check the vacuum advance for movement as you rev it up a little. Then disconnect it and rev it up a little and see if it advances. If not, remove the breaker plate and see what's wrong.

Last edited by crenwelge; 12/12/2009 6:55 PM.