Is this a real timing issue?

[sggoat]

History-
~ 6 months ago rebuilt the head on my 77 2F.(valve job-new springs/keepers/4 new valves). Points looked good, as did the plugs, so left them alone. Ran great. fast forward to about 1 month ago--noticed a little ragged idle(down to ~ 600 RPM from 650.) Vacuum was down ~ 2 in. Hg. Vac steadily declined over the next 2 weeks to almost 17" at idle. Capt. Conch and I sprayed everything in the engine bay to see if we could find a leak--nothing.
When the vac got to 16.5-17, I opened up the dizzy to check the points--(hanks to the vac troubleshooting guide here)--
Found the points almost fused together-the little wiper that contacts the dizzy shaft had worn past the gap width--essentially the points weren't opening at all.
Went ahead and replaced points/plugs/rotor/cap--Everything seemed to return to normal--idle vac was back to 20.5, idle rpm was back to 650
2 weeks later, notice the engine is hard to start cold--sounds like one or more cylinders are firing BEFORE the piston gets to the top(it almost wants to run backwards-the starter labors hard on a couple of cylinders during startup)
Does this sound like too far advanced ignition?

 

[honk]

Could be, but with new head work I'd retorque the head and reset the valves before fiddling my tune trying to find reasons for mysterious changes in how my truck runs.

 

[sggoat]

Valves are easy--I'll try them 1st--thanks

 

[B y r o n]

. . . the little wiper that contacts the dizzy shaft had worn past the gap width--essentially the points weren't opening at all.
Went ahead and replaced points/plugs/rotor/cap--Everything seemed to return to normal--idle vac was back to 20.5, idle rpm was back to 650
2 weeks later, notice the engine is hard to start cold--sounds like one or more cylinders are firing BEFORE the piston gets to the top(it almost wants to run backwards-the starter labors hard on a couple of cylinders during startup)
Does this sound like too far advanced ignition?

Have you check the wiper to see if it has worn away again so thing are firing sooner than expected?

 

[65swb45]

Think about this. Point gap is an approximation. What you are really after is dwell DURATION. Duration is a function of time and energy. So time is an element, even though not in the way you are thinking.

Check your work with a dwell meter. Not just at idle, but at 1200 and 2000 rpm. Your distributor bearings may be failing.

BTW, I finally put that hardtop glass back on the shelf you inquired about.

Mark