Trouble tuning 340.

If your car has hydros, you should be able to crank adjuster to zero (finger tight on the pushrod) then turn it even more and the valve will not move as there is .060 preload minimum on those hydros with no oil pressure. Solids will move once snugged. Check TDC on balancer to #1 rotor phasin and plug wire order. Simple to swap a pair of wires when your rigging it up or just drop the drive in 1 tooth off. Even some solids will have a snap ring so thats not 100% unless you see no snap ring at all, thats a solid lifter for sure.

Well now, we got more info. If it idles poorly in gear, your mix is off. If you installed headers, its gonna lean it out, if you went back to manifolds your probably fat. IF you got an exhaust leak (318 manifolds on a 340 head) its gonna run like crap and sound terrible. Same as a vacuum leak, may run but youll be chasing the idle. Start spraying the manifold gaskets and carb with water from a spray bottle and listen for the idle to change.