440 carb selection what your thoughts?

kjalltrac · Sep 28, 2015

I´m looking for some input on this subject.
This is my combo.
stock bottom low comp 440
comp xe284 hydraulic cam
dur @50 240/246
lift 0.507/0.51
lobe sep 110

452 heads, stock valve size, back cut. shaved 0.04, pocket ported.
8.5:1 comp
Edelbrock rpm manifold
1 3/4 headers
3" dual exhaust
msd 6A ignition
19 deg initial, 39 deg at 2000rpm

Stock weight Belvedere 1964
727 trans with Transco tf2 kit
3000 stall converter
8 3/4 rear with 3.73 gears
will use 26" slicks at track.

I have an A/f meter for tuning.
( also have a lot of holley jets, gaskets, cams, etc.)

The car is mostly used as a weekend street car and do a little racing but not as much as I want to. (lack of tracks and events here)
I guess I want the best of two worlds here, good street/drag performance and pretty good mpg.
I do drive the car pretty far on vacation to car meetings and tracks.

I have tried a holley 850 dp, It felt the strongest with this carb but had terrible mpg on road trips and was not "low cruise friendly".

I´m currently running a edelbrock hp750. Tuned it with the leanest rods and jets in the edelbrock tuning kit, but still a little to rich at cruise, slight bog when flooring it from under 1500rpm.

What do you think about the quick fuel 780 vac sec (hr-780-vs)?
Maybe the edelbrock 800 thunder series can be a option?

This engine will probably see a 100-150hp of nitrous in the future.

Seventy · Sep 28, 2015

http://promaxcarbs.com/ call these guys and get them to build you a carb...

terzmo · Sep 28, 2015

proform 750 with mechanical secondaries

kjalltrac · Sep 28, 2015

terzmo said:
proform 750 with mechanical secondaries

I´m afraid the mech sec will be a little thirsty for my long road trips?
The thing I like with the quick fuel is that it has screw-in air bleeds and idle feed restrictions, quick adj of secundaries and 4 corner idle screws.
I guess my next question will be: Vac or mech secundaries? But I lean towards the more economic vac sec.

IQ52 · Sep 28, 2015

terzmo said:
proform 750 with mechanical secondaries

Interesting suggestion. I have a 440 on the dyno right now with that exact carburetor (mechanical secondaries and electric choke) and the same camshaft with Stealth heads and a RPM manifold. The carburetor comes with a selection of links to adjust the time at which the secondaries begin to open.

Runs very, very rich. We will be working on that problem some more today. I mean, it is running okay even as rich as it is, 540 lb-ft @ 3,700 rpm and 512 hp @ 5,200 rpm. Which is a few more horsepower than we made with the 850 Mighty Demon we used as the dyno carburetor to fire the engine up with.

kjalltrac · Sep 28, 2015

IQ52 said:
Interesting suggestion. I have a 440 on the dyno right now with that exact carburetor (mechanical secondaries and electric choke) and the same camshaft with Stealth heads and a RPM manifold. The carburetor comes with a selection of links to adjust the time at which the secondaries begin to open.

Runs very, very rich. We will be working on that problem some more today. I mean, it is running okay even as rich as it is, 540 lb-ft @ 3,700 rpm and 512 hp @ 5,200 rpm. Which is a few more horsepower than we made with the 850 Mighty Demon we used as the dyno carburetor to fire the engine up with.

I would really like to hear what carb you would run if you had the car/combo I have now.
I had big trouble with the transition on the holley 850 dp on the street and never got it quite right. But what I know so is the 850dp a race only carb.

mentor70 · Sep 28, 2015

i bought a holley 850 HP ultra this time around, there is no calibration in this piece that cannot be tuned. my car is a 4 speed, that was 99% of the reason i went DP.

that being said, if you cant adjust the idle circuits with a big cam, life will be miserable.

i did a 440 years ago with 8.5 comp, 509 MP cam, Edelbrock RPM, holley 750 vacuum secondary, that setup didnt run for ****, so i took the six pack off my Cuda and it worked like a champ.

IMO, all the other carbs you have listed are one step backward from the 850 holley.

you need more tunability, not necessarly a different/smaller carb, your exiting carb could be modified.

i had an 850 demon on my last 496, the carb size was ok, but without idle circuit mods, it was worthless.

i had adjustable idle bleeds installed and problem solved.

furyus · Sep 28, 2015

My combo is very close to yours. had an 850 dp on my Sport Fury. Would run 12.50-12.40 with the 850. Tried a friends 650 race carb. Went 12.20-12.15. Tried a 750 Race Demon. Went best of 12.12.
When you talk about fuel mileage, you are only running on the primary anyway, so you just need to tune them. Doesn't matter if it is a vs or dp. I tried a 780 vs once on the street. I could feel the car slow down.
Besides a 440 with the setup you have Isn't a recipe for good mileage. I would have those heads cut to up the compression, and run a Holley/Demon 750 dp. You will have to work with any carb so it doesn't bog when you floor it.

Cranky · Sep 28, 2015

What's your cranking PSI on this engine? Imo, your cam is a bit big for an 8.5-1 motor with big exhaust.....

kjalltrac · Sep 28, 2015

The heads are cut .04 and Im running steel shim head gaskets.
The proform I belive is more or less the same as the quick fuel carbs.
Really appreciate everyones input on this.
Just cant decide if I gonna go vac or mech sec???
I want screw-in air bleeds and idle feed restrictions
Electric choke
750-800cfm

1wild&crazyguy · Sep 28, 2015

With a combo like that i would use something in the '750'-830cfm range, i personally like mech secondary style for getting on it and with stick/manual valve bodied autos.

I like holley and demons, but I always go through either before running them 1st to get in them in shape for the combo and 2nd for any debris inside..

kjalltrac · Sep 28, 2015

I always go thru the carbs before I use them.
However, Just received recommendations from quick fuel, they recommend the SS-780-vs for my combo.
I believe my combo is right between the use of vacuum or mechanical secundaries, would be fun to see some actual 1/4 mile testing between the 2 types of carbs.

Roughbird72 · Sep 30, 2015

My .02 ... a 3310 Holley

GTX MATT · Oct 1, 2015

I have a 9381 850 DP and the transition is extremely rich. Squirters OOTB were also too small, my setup needs a 35 or 37. I jetted it down 3 jet sizes front and rear. This carb still needs alot of work to get it straight, but runs better than any vacuum secondary carb I tried.

I have a buddy who has had very good luck with the 800 AVS on a 906 headed 440 with an original torker intake and a Comp Magnum 292 cam (244 @ .050). That car has awesome throttle response, I was impressed with it. He has a 4K stall converter and 4.30s, but he was running an 850 DP before that and said he could never get it anywhere close to the way the AVS ran out of the box.

lewtot184 · Oct 1, 2015

believe it or not this set-up has very good throttle response, starts easy, drives great, and the fuel mileage isn't any worse than anything else i've ran. down side is fabbing some brackets and the tiny air filter.

440 carb selection what your thoughts?

kjalltrac

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Seventy

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terzmo

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IQ52

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Cranky

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