I run an HEI in my chevelle on a 350 small block. Whenever I got the car it ran decent but it didn't have an electric choke so i added one and it ran fine for a while. Then it seemed like sort of suddenly one day when we started messing with the timing it started to just go haywire. Me and my dad couldn't figure it out we went out driving just setting it by ear ie listening for the pinging and backing off from there. Well when we got it where it seemed it ought to be i get on it once and it revs up great barely a hint of detonation and good power. Then just driving along i start to go WOT again and it starts pinging all over the place. We try resetting the timing with similar results. Finally we pull off the vacuum line for the vacuum advance and after that we can get the timing set right. I take the car to a friend and we pull the distributor and discover the posts for the weights are looose so we frankenstein together a distributor with all good parts from the various ones he has laying around. Even after that its impossible to get it to run right with the vacuum advance. He even tested the vacuum bell or whatever you call it with his vacuum tester so i know its good. The only thing i think might bother it is the fact that i have the vacuum hook up for the electric choke tied into the vacuum line for the distributor. Would that be able to cause this sort of eratic behavior?