Back in the late seventies, I had a 73 Duster 340, 727. PS, PB and A/C 3.21 gears. Bought it used in 1976, with 50,000 miles on it. My first job out of school, I had to drive 45 miles each way to work. Was getting 12.5 mpg. Plus, it was inconsistent at the strip, vapor locking half the time, and varied over a half a second range even when it didn't vapor lock. I milled the heads .030, slapped some .039 FelPro head gaskets on it, swapped the 73 intake with floor jets to a 71 intake, and bolted on a Holley 650 spread bore carb. Gas mileage went from 12.5 to 16.5, never vapor locked again, quarter mile times became a ton more consistent (tenth of a second from worst to best), and almost half a second quicker, fastest run to fastest run.
Over the years, I've run Edelbrock carbs. OK, but they don't like high volume mechanical fuel pumps, and are more prone to vapor lock than Holleys. Plus, Holleys make a bit more power, even when the cfms are the same.
I'm presently running Edelbrock carbs on a slant six, a 277 poly, a 289 Studebaker and twin AFB's on my 426 Hemi. Invariably, they flood all over the place if left sitting for a month or two. Needles and seats. Clean or replace them. Most recently, on my 63 Valiant convertible. Looked OK at a casual glance, but the needles and seats had some kind of corrosion - just enough to stick. Replaced them and they were OK. And this was a fairly new carb.
I know these issues stem from the bad gas we get these days, but Holleys seem to deal with it better - as long as you're running blue accelerator pump gaskets. Black ones will rot and leak.
Just my experience over the years. And I know there are plenty of people running Edelbrock carbs whose cars are quicker than mine So take my opinion for what it's worth. I prefer Holleys for anything over 300 cubic inches.
