68 911L Timing issues

Need some help. Stock 68 911L can't seem to properly set timing. Newly rebuilt engine, MSD ignition sys, Idles ok at 1200, slight throttle increase causes rapid increase to 2500-3000 rpm. Sounds like advance mechanism is not functioning? Timing seems to be at TDC at 1200 rpm. What am I doing wrong? Everything worked well for last 1000miles?

What did you change since last thousand miles?

When it's cold and/or warm?

air leak.... but i am not a mechanic

If distributor all good, Wd40 areas of pedal cluster, carb linkages, throttle bodies.


Filter off, hand blip engine speed at the rear, watch for return.