[Argess]

I have a 2x4 set-up from Pony Carbs. I find that changing to the Holley Blue Accelerator Pump Cams helped a lot with acceleration. Cheap to try. Don't forget to buy 2 kits.

Also, consider setting your initial timing up a bit. Just keep your max timing at 38 or below. I am currently running at 20 deg intial and there's more room to go. With your heavier car, I still would try keeping it up past 18 if you have any kind of performance cam installed. If you are using a vacuum advance, all this is not so critical to acceptable performance.

I dont' think this would cause your issues, but is your linkage progressive and adjusted right? Both carbs should arrive at fully open at the same time, but front carb is open about 30% (more or less) before rear one opens.

Finally, does it belch balck smoke? If a power valve fried, then it will run rich at low rpms and make acceleration difficult.

PS: I just reread your post and see you ahve tried some of the things I mentioned. But, put your vacuum balance tube back on. That shold not be an issue. Rusty Bob is corect about timing being off a tooth causing trouble, but miostly it causes a limit to rpms, not some of the things you are experiencing. Typically, if an engine accelrates fine slowly, but not under ahrd accelration, it is a accelerator pump issue. Try the blue cams in #1 hole first, then perhaps #2 hole if needs be. Tunnel Port....may need a ton of fuel to get it revving into the power band where the main metering takes over.