Agree with Drew - ANY carb you buy these days, I would take apart and clean with B-12 and air.
Here's a couple of cents from me lol
Ford 4100 - kinda rare, hard to find a good one these days especially the larger venturi items. Jetting tricky I think because of lack of parts and the jets are not HOlley size. They work work very well. Big annular boosters make for good low speed operation, especially with a heavy car, street gear, street converter, etc. The Falcon with a stock 289 C code, iron 4 bbl intake, junk yard small venturi 4100 3 speed, F60-14 bia tires and 2.79 rear went as quick as 14.6 @ 96 at Green Valley.
Summit -
https://www.summitracing.com/parts/sum-m08600vs Good units, didn't sell for Holley because "that donna look like no Holly carb to me". Booster design like the 4100, the rest takes standard Holley parts - jets, choke parts, accel pump diaphragms and such. Vacuum secondary control units same as Holley, same springs and such. Top removes like 4100 for service and change jets. Pump shooters adjusted using pin drills to mod the booster passage. That used to be a problem but now that Summit has the line, replacement booster parts should be available. I ran a 750 vacuum version on a 3350 lb car, 11" converter, 3.25 gear, 351V 4V open chamber, Weiand single plane BFG street tires. Drove great, ran 8.40s in the 1/8 mile, that's low 13s in the 1/4. Still have the carb.
Edelbrock - comes with a very good turning manual, just have to buy a tuning kit for extra $$ to get the parts. Basically a Carter re-man. Looks like a mini spread bor from the bottom. Primary bores are smaller and have very efficient boosters for great low speed mixing. Secondary are weighted air vane controlled by primary air flow , opening rate tuneable on the AVS series. Throttle plates open primary, then secondary like a double pumper. Fairly easy to tune, do have to remove the top and linkages to replace a jet should your turning require it. Accel pump travel adjustable (three positions). Metering rods drop in from top so real easy and can control the rod lift rates (enrichment) with tuning kit springs. Limited selection of shooters for accel pump, but the .033 usually works if the stock .028 doesn't. I think the next up is a .045, so you can buy a .028 and use pin drills. Problem is you have to remove the top to RnR the shooter. But once tuned - and they work pretty well right out of the box - it's set and forget. Back to back Ed 600 vs Holley list 1850 on a mild 302 showed Ed +2 MPG for the win. I've also run two of the Ed 600s on a tunnel ram and had them work well. Also used on a daily with good results. On a cast iron intake, stock closed hood - would recommend a heat shield and a non-metallic spacer to control heat if you live in a hot climate. Stock type Fors setup - iron intake, crossovers open, aluminum PCV spacer - in Texas summer can boil the fuel right out of the bowls.
Holley - everybody has one or two or 23. Modular, well known, parts common as dirt. My wife rebuilt one while we were dating. Have to drain the bowls to change jets, even if you run it dry with the motor from shutting off the fuel pump. Always use Holley brand blue non-stick gaskets or you'll be sorry IMHO. I don't like the QFT gaskets - harder than the Holley parts and the bowl gaskets usually require trimming around the pins, especially if you are using some replacement billet metering blocks. I even use the Holley blue parts with methanol. Not as good as Buna-N when running alcohol but good for a typical season. Many Holley post-rebuild issues come from mis-placed power valve gaskets (leaks right into intake if not centered correctly) and metering block to main body cross passage fuel leaks. Super tuning a Holley starts usually with machining or filing flat the main body faces to restore good sealing with the blocks. The faces and block warp from people putting 47 ft/lbs on the bowl screws. PV gaskets tend to deteriorate quickly these days. "Blown power valve" is what is wrong with every Holley carb, however it's truly a very rare condition. You need an old base plate and a hella backfire to break one. Standard dog leg boosters are the lowest on the efficiency scale. They work, are cheap to Mfg. Down legs on the larger carbs are better but still mainly come into their own with higher air flow rates. Carbs can be had with annular boosters. "List 3310", vacuum 750 is likely the most common carb used on 300~400ish CID engines. First thing you do with a used one is look at the close for hacks before paying for it, then return it to stock configuration before you bolt it on and test. Give a guy a Holley and a screw driver and there's an 60% chance it's going to not run right after he "tunes it up". After any adjustment, you must wing the throttle 4~6 times - that's required. Kidding aside, very versatile units. The DP series has so many sizes because you can fit one very close to an engine's requirements. The 4777 650DPs are really nice all around units. I have one that runs right on a 250 HP 302 or the 575HP 393 on the dragster. QFT aftermarket billet metering blocks are a good upgrade. ProForm blocks - meh. All billet base plates assume 4 corner idle, so on older units you'd want matching metering blocks. ProForm main bodies are usually pretty decent parts but are air bleeded for 4 corner idle, so have to change some parts to update a 2 corner idle stock Holley. I built a 750 vacuum using QFT blocks and a ProForm center, loaned to a friend running a 454 in a Firebird with a 850DP one night. Car picked up 5 MPH and nearly 1 second in 1/8 mile. Like to never got that carb back. QFT, others are all basic Holley DNA, the rest is in the setup and tuning. Barry Grant had some good stuff in his day, but was a total asshole and later on quality went to hell. I have one of his fuel pumps that likes to run full pressure until you need it, then go to zero. Performance back to back 600 DP vs Ed 600 showed Holley for the win by about .02 in 1/8 mile. YMMV of course. For a lot of strip performance applications, the best bet is to hand the carb to someone with a good rep, then bolt it on and run it. Put the screw driver in the tool box after setting the idle mix and speed. The Holley HP series has a decent track rep for running well out of box.
Yes, I've seen a tuned Quadrajet blow a Holley's ears off on the dyno. Very complicated metering devices, but work excellent in the right hands. Not my hands.
