My '56 350 Vortec / 7004R stumbles after starting to move, and needs help with Performer tuning. The local shop did replace the springs with lighter ones, supposed to give more fuel with Vac drop intial start. The car doesn't gasp or stumble until already moving, like 1/2 way through the stop light! Rapid foot accelerator pump will overcome the stumble, so I am thinking the basic jetting needs a change? Dunno, never had a performer. Is there a place on this site with step by step Performer setup? I figure folks here will have separated the theory from the practical, ..... What actually works!
Honestly those carbs are troublesome once you get above a completely stock 350. A Holley or Quick Fuel Brawler 650 would be my choice. I'm running a 650 on mine & it's very responsive with only a mild tweaking.
55 Bel Air Two Door Sedan
350, 4 speed, 3:55's
A Performer carb tunes just like any other, except that the parts to do it are different.
If you have a hesitation, you probably need a bigger accelerator pump nozzle, just as with a Holley. Edelbrock sells an assortment of 3 bigger sizes, cost is reasonable and Summit stocks it. The other half of the hesitation story is not carb related, it is ignition timing. Usually when there's a hesitation you need more ignition timing - more initial usually takes care of it.
There is a tuning manual that comes with the carbs, I think you can find it on the internet also. It shows what combo of jets, metering rods, and springs comes with each carb, and what the configurations are for incremental steps of richer and leaner.
The only deal on working on these carbs is that nozzle and jet changes are more tedious to do, though not a lot. I prefer to remove the carb from the engine to make changes, something I rarely do with a Holley type carb.
I'll jump on the remove the Edelbrock carb and replace with a Quickfuel or Holley Brawler bandwagon.
I've had Eddy carbs on a few different engines...same problem as you. It's widely known as the Edelbog. I put on a 750 VS and a 650 VS SpeedDemon (on two different engines) and they not only ran better, but idled better and made more power (according to my accurate butt dyno).
Dump it and it will go away. They're just not great carbs.
I've probably owned a dozen and a half Holleys. I've owned exactly one Edelbrock Performer, and one Carter AFB (which it was copied from). In general, they all respond to the same tuning principles. Holleys are much easier to work on, but the Edelbrock Performer/Carter AFB isn't that difficult. Also seems to me that most Holley carbs newer than 25 years or so are a POS as far as idle quality on a street engine. The most popular part numbers of both are pretty close on main jetting right out of the box.