85 12A timing/miss fires problem!
 

my 85 12 A rex has odd miss fire, when i try to time it. the yelow mark dose not apear till i rev it up some, then when it idles i shows up but it jumps i cant have it timed perfect and then it will jump 1" from where it was at. and it seam to only hapen after a miss fire. I was wunering if that would be from a bad distrebutor system i changed the spark plugs, cap and rotor. the trailing timing mark is allso doing this.
thanks for your help

Do a search seriously search you will find the info you need. To help you out you need to have the motor revved to 4000rpm's to time it properly. Disconnect the vacuum advance and plug the vacuum hose to the motor so you don't have a leak. You rev the motor to 4000rpm's so you have full advance and then you can make your adjustments. I'm not going into full detail here because like I said do a search.

thanks