[formulabird428]

Hoping I can get a direction from the PY forum:

Symptom:
Starts right up, idles nice when cold (have to feather it until about 140F). I drive it around and it runs great. One thing I do notice is that the A/F ratio is a little higher than normal -- maybe 0.5-1.0 points higher. Where it used to idle at 14.5 to 15.5, it's now from 15.5 to 16.5. Coming off of a cruise and stopping to idle, it goes above 18.0. I get it a little throttle, and then let it rest to idle again, and it returns to 14.5 to 15.5. Again, car has always done this, but it just "seems" to be a little leaner. In light throttle, it's about 12.5, which is pretty much where its always been for the last 5 or 6 years.

After about 25 minutes, it breaks up bad. Pops through the exhaust once or twice. I pulled it in the driveway, very hard to start. Backfires a few times. I actually had to pull it back in the garage today, since it wouldn't start at all afterward. Pulled Cylinder 1 plug and it was dirty, threads were wet, but tip was black-brown.


It has an HP 830 Holley with a new baseplate. Jets are something like 79 / 84 or something like that. I do have the back blades cracked open to allow for more air at idle. The T-slot is .030" showing.


Some components are old, but I don't drive the car more than 200 miles per year.


MSD 6AL ignition w/blaster 2 (coil is about 5 years old, 6AL is about 8 years old)
NGK plugs (about 4 years old, 1500 miles)
Holley regulator (this thing is all over the place, could be a problem here). I can't seem to set it and have it stick to a number. It will idle at 10, then drop to 4, up to 7, etc. Any recommendations for a better regulator?
Recently set the lash @ 0.020 / 0.022 per Reed Cam Card, but it is smooth as glass up through 5k rpm (when cooler - 160 or 170, not 190F hot).
Not that this matters, but oil pressure is good.

Any thoughts? Fuel delivery? Carb? Regulator? Ignition?

Thanks in advance.