So what happened???

I've been working on this 304 all day. Running crappy,dead spot in the pedal off idle. Looking for vacuum leaks, checking timing, looked at vacuum advance and adjusting idle mix. Which had no effect by the way. Finilly I moved the vacuum advance tube to the right side of the carb, no difference at first then it backfired through the carb and "viola" suddenly it runs fine. Been driving it for two hours without any problems. Was there junk in the carb or just pfm?

 

Did you move it to a different vacuum port? Did you check that vacuum hose real good, might have a crack in it that closed when you moved it?

 

I'm going to pick up new vacuum lines and a new carb gasket. It ran poorly this morning, getting better as it warmed up. Stiil had a little miss in it untill I revved it pretty high then it smoothed out again. Think I'm going to have to rebuild the carb. And get some of those copper header gaskets.

 

Sounds to me like a problem with the power valve in the carb. Be sure your rebuild kit contains a replacement. Carb kits are available with or without the PV.