Okay, I was with you right up to the valve overlap of the cylinder. Is that the top of the compression stroke when both valves are closed? Dad tried vacuum timimg and with a light when he owned it. Timing was my first guess when I drove it also. He says is seems "happiest" where it is now. (cant remember off hand how many degrees bef. TDC that is, but close to the factory mark) I think I'm posting in a couple of places. I found out that Dad thought exactly like that about the carb. Joe,,, Replaced whatever was on there with the big Holley. Cant remember what the part number is, but looked it up on the Holley website and shows to be a 750. I actually talked to one of the techs on the phone and he had a formula for rpm, hp, and flow. Said the 750 will cause hard start, no bottom end torque, and poor fuel econ. -exactly the symptoms I'm seeing...Suggested a 570 Street Avenger, (vacuum secondary manual choke) which I bought new off ebay for $322. Also have a new Holley fuel pump/regulator/psi guage, and misc. pieces parts. Got a week vacation coming up the 5th for the big tear-down and rework. Currently the wimpy little fuel pump is pushing fuel 25' thru 3 filters to get to the back of the bus. I'm wondering if its just running away from its fuel supply?!