Oh I'm sure this has been brought up. I rebuilt a 1971 LA 318 and Installed a thumpr cam, headers, aluminum heads and edelbrock 1406 carb. Problem is that engine shakes alot at idle below 1000rpm. People say 1000rpm is about right but Im looking for that low choppy sound instead of a high idling motor. Already drilled 1/8" hole on my primary butterflies for afm adjustment but still can't get it to stop shaking anything below 1000rpm. Locked timing at 36 and still shakes. I know edelbrock 1406 is lean so I already changed the jets but that has nothing to do with idle. Changed to the weakest step up spring to. Haven't been able to do any tweeks lately do to an almost electrical fire.