So I just took my 66 to the shop to have the carb adjusted and the headers tightened. Now it "stalls" and then surges every 40-50 seconds. (On a side note, the electronics/lights go visibly dim when it stalls) This happens in all gears and when I'm driving, the surge is so hard, it feels like a shift and when the surge happens while shifting, it's kind of scary. Any ideas as to what it might be? Is the engine just settling into the newly tightened headers? Other then the stall surge issue, it runs like a champ.
-New carb, new headers, Specter air intake, Larger valve covers, MSD distributor, new battery, new power regulator, new Masterflow exhaust, new alternator.

Any help would be greatly appreciated, thanks.

 

I would take it back to the shop and have them fix it...

 

Mine used to stall out until one day it stalled and never started.. Today I changed the ignition switch. The ignition was shorting out when it was in the "on" position. And after that it ran beautifully without stalling ! Best $13.99 I've ever spent! ( I also took each spark plug out an cleaned them.. It runs a lot smoother now)