Hvymtlc5

What kind/size of Holley 4BBL would make a good daily driver for a 400HP - 454, with automatic /3.08 gears? I currently have a 750 Mighty Demon (no choke - double pump) and think it will be too much once the current cam is is downsized to something an little more street/fuel friendly.

I do I a Holley 750 sitting around that is a single pump, vacuum secondary with choke.

forvicjr

O im going to get flamed on this one, MY preferance is the mechanical secondary(double pumper) to me there easy to tune over the vac sec carbs.As far as the rating there the same in size.Though im willing to bet the demon flows a tad ove the 750 mark.

Timsride

I agree with forvicjr. I prefer the feel that mechanical secondaries give.A properly tuned vacum secondary is close but not quite the same.The motor really does not know the size of carb on it.If Your doing this to make a real impact on gas mileage, then I would consider puting a small block in it. You will also gain in handling. You will have to retune the carb but it should work fine. Just my 2 cents worth.

Hvymtlc5

Partially, but the car needs to be able to start and idle in cooler Illinois weather (need for a choke) so she can drive off without waiting for it to warm up like the Demon requires.

marshrat99

On my 355 I'm running a 670 Holley SA, vacuum secondaries and electric choke here in Northern Ohio. I've a 70 454 Chevelle that I'm rebuilding and am seriously looking at the 770 Holley SA, vacuum secondaries and electric choke.

baxsom

a mechanical secondary on an automatic car with that gearing will not work correctly according to every single paper out there. I have a 750 speed demon with annular booster on my 454HO with th400 trans and it runs great. There is no way a the words 454 and carb can be said with the words fuel friendly though. I get 8 mpg and have no problems paying for every drop of it.

73StreetRace

I don't think a 750 cfm carb is too much for a 454, even with a mild cam and street use.
I'd even call that a minimum
I would keep it if I were you. I like double pumpers too

CFD E59

I had a simular delema recently, and I chose to go back to a Quadrajet. It runs strong and can easaly tweaked for your application. Before that I had a Holley 750 Vac Sec.

JimT

Before you buy, do a search on this forum for Holley Carb Problems. There are a lot of issues discussed. I wish I had.

baxsom

yeah but there are a whole lot of people that are satisified with theirs too. if it already has a square bore manifold on it there is no reason to change it.

PowdercoatBill

I'm a Holley guy myself, but in your case I'de keep the Demon. You can always jet it up or down and don't they have screw in air bleeds? You can make your adjustments once the new cam is in.