I've heard a few folks say that progressive throttle control of the carbs is not the best method even though the factory set it up that way. What's the opinions of guys who have done both ways?
I have a progressive linkage on my Dual Quad set-up. I don't want to run on 4 barrels all the time. Gas mileage is bad enough as it is.
Both operating the same is mostly for stick shift set-ups. As mentioned progressive for most automatics.
I had progressive when my GSX was a street / strip 4-speed car. Started out with two 600 cfm Carter AFB Competition carbs, all tuned with there "strip kit" and then some. Put two 750 cfm Carter Comp AFB's on and the car picked up at the track and drivability was way better. Even though there's two carbs do NOT go with the smaller carbs. Even for street driving. Yeah, I wore out my Strip Kit. lol Was fun with the 4-speed. You could really feel the second carb kick in both by feel with the peddle and acceleration.
Not that you were running a Nailhead in your GSX but I always wondered as to why Nailheads love big carbs but put out less power with 2 500 AFB's than a stock sized Q-jet? 2 500's are 270 cfm more than the Q-jet. Ok I kinda understand theres alot more than just carb sizes involved such as different runners between the 2 different stock manifolds, but at WOT your getting a 1000 cfm over the 730 cfm stock but less power. The factory dual quad is well designed and so called still one of the best, so it must be designed around the 2 625's for the street version. I think it was "Hemmings Muscle Machines" that did a very mild 401 build using 2 500'a and only made 329 hp but did hot 500 ft. lbs. If they did more research and used the bigger AFB's it would sure put out better numbers.
edelbrock sells a 2x4 intake for mopar 413-426-440 and tells you to run 600 cfm carbs and gives you the jetting to lean out about 8% over the stock carbs. i actually tried 2-500 cfm carbs with a lost of power you could feel on my 440. on my 446 ci nailhead i always ran 2- 600-cfm but i did try putting one 750-cfm on the rear carb and lost low end power and throttle response and no more top end power. 2 x 4 has more plenum area so more carb.
Since no Carb is directly in the center like on 3-2 bbl set up to provide balanced flow to all 8 cylinders you want to run 1 to 1 and make the jetting and accel pump changes and adjustments to get it run clean, period! I have seen a motor where the guy did a brilliant job of making the needed throttle linkage to turn the 2 Carbs such that the primary's where in the center of the manifold and facing each other, then you can run progressive!
