Your getting the quick throttle response from the small 650 venturi size which gives you high velocity. Our experience has shown us that the 351/385 in a light car like yours likes the 650 Mighty Demon for street application.
The Mighty 650 will give you even better throttle response over the Holley. It's designed to read the low vacuum signal from that engine and will flow more air at the top end of the power band than the Holley...all around just a better carb than the old Holley design. The comparitive Holley would be the HP carb at $639.00
(I'm sorry but that is a one ugly carb)
I have a customer who's the Top Diveability Tech for a large local Toyota Dealer and he's a very successful Drag Racer....he bolted down one of our 650 Mighty Demon's on his 395 HP 355, 55 Chebby Hard top Hot Rod last weekend....turned the key and it ran perfect with the exception of the idle speed, it ran at 1050 instead of the desired 950, 1/4 turn on the P side and 1/4 on the S side and it purred.
.......$499.00
He hooked it up to his 5 gas sensor at work....never took a screrwdriver out of his tool box, needed no adjusting.
I know this is a long way from a Cobra or Mighty Mopar, but it's just an example of how well these Mighty Demon carbs work right out of the box (with our baseline set up) even under the scrutiny of a tuning professional.
You just can't beat them for $499.00
I'm sure that Quick Fuel does a fine job of re-building and modifying Holley carbs. Obviously they have corrected allot of the issues on the Holley's but with a price ticket of $690.00
There's no less than 500 shops modifying, improving, rebuilding, replating and swapping out Chinese parts in Holley's and I'm sure that most of them do a pretty good job after all there's plenty of room for improvement.
Some of these guy's stay around for years and some just fade away. Most of them depend on their existance by the longevity of the owner...when old Bob retires the company goes into the history books along with the tech help and parts availability.
So why is it that there is virtually NO Company's anywhere that are modifying or "Improving" the Demon carbs???
Could it possibly be that there's nothing that can be done? How do you improve on the Demon air horn? The metering blocks are Billet so they don't leak, the float bowls are huge and don't leak, the base plates are billet....what would you change?
125 different Demon carbs for every conceivable application, good Factory tech support, excellent parts availability, easily tuned.
To my knowledge there's only us and one other company in NC that will modify a Demon carb and both of us are limited to setting them up specifically for Drag Racing, Road Racing or Off Road and we're both using parts right out of the BG catalog.
BG Inc. tech department and service parts will be around long after most of us are long forgotten.
Up untill about 4 years ago we would overhaul and repair Holley carbs, we stopped. The standard work order would read "Modified by XYZ Company" most of the time the company was gone or the individual couldn't be found. We found that in most cases it was cheaper to just replace the carb with the correct Demon for the application, the car would run better and the customer got away cheaper and happier. Chasing some unkown metering block and trying to figure out the circuitry was too time consuming. Time is money we're no different than any other shop and we have to charge whether we're hunting parts or assembling a carb.
When you invest in a $500-$800 carb for your pride and joy do you really want to gamble that the guy your buying from will be around in 3-5-10 years when you need help to rebuild or repair it?
IMO I doubt that Holley will be around in 5 years as we know it today. Remember where you heard this 1st, there's some major changes coming to Holleyworld. Might be next month or it might be 3-4 years but there's a shake up coming that will rock the performance industry. They've already closed the technical and service department for all pumps, so you racers out there that own a $500 Holley race pump be prepared if it looses a seal you'll writting a check for another $500, there is no parts available.