As was mentioned... Timing will affect carb, carb will not affect timing. So you set the timing first. If this is a points distributor, timing affects dwell, dwell does not affect timing, so again, timing first. If everything is connected including the vacuum advance can, for purposes of diagnostics disconnect and plug the hose at the vacuum advance. If the surge goes away, you need to adjust the vacuum advance. As far as a base generic timing settings.. If the engine is stock to mild with iron open chamber heads I'd use 14° initial, 38° total, plus the vacuum. Get a set of Mr gasket light advance springs and replace the near-solid stif one with the lightweight one. Then see if it still surges. If it does, plug the vacuum advance line and drive it. If it goes away, post, and we'll tell you how to fix that. I highly doubt it's the carb. Possible, but generally never start with a carb. Start with timing, and timing by ear is like cooking by waiting for the smell of smoke. use the light. That's what they invented it for...
