Engine Build with 6 Pack Carburetors Question

[70_440-6Cuda]

I have a 440 3x2 with stock rebuilt carburetors.  Planning on building an engine with Trick Flow heads and Edelbrock aluminum intake manifold and stock carbs.  Going to run a fairly aggressive cam, roller rockers and MSD distributor and ignition set up, headers etc.  Not looking to build a race car, just figure this is easy bolt up HP.  Not going to pull apart the stock spec bottom end as I dont want to spend a fortune and this should make plenty of power.

2 Questions - anyone have any experience / recommendations on the heads and how much HP are the stock carbs good for?  Obviously originality is not a concern here, but I have the carbs ready to go and would like to keep the 3x2 look and will likely paint the heads and intake for a more stock appearance

[pschlosser]

i believe the stock 3-2 setup is good for 1250 CFM

[jordan]

I have stock 3x2 set up on my Edelbrock aluminum intake big block. Carbs are reworked with a jet plate.  Make well over 500 hp and over 600 torque.  I think your intake will be good for a bolt on HP engine. 

[RUNCHARGER]

The Trickflow 240's are excellent heads and are what I would use on a streetable 440 buildup. 2 bbl carbs are rated different as compared 4 bbls but the six pack CFM works out to 940CFM as compared to a 4 bbl carb which is right where you want to be. The intake manifold will actually be the cork in the system but not that bad and you'll be happy with the results. Myself I would port out the intake manifold to get a bit more out of the combo, the heads aren't going to hold you back.

[Chryco Psycho]

The only problem I see is the idle circuit , it is nearly impossible to modify the air bleeds smaller so they work with an aggressive cam .
A trick I have used a lot is to use a small piece of welding wire pinched between the squirter & the choke horn going into the air bleed to restrict the opening , you will need to experiment with different gauge wire to get it right or bending the wire double even at the ends where it goes into the bleeds .
You will also have to tune the springs in the outboards , they may need lighter springs as they will open too slowly .
I agree with porting the intake .

[70_440-6Cuda]

The only problem I see is the idle circuit , it is nearly impossible to modify the air bleeds smaller so they work with an aggressive cam .
A trick I have used a lot is to use a small piece of welding wire pinched between the squirter & the choke horn going into the air bleed to restrict the opening , you will need to experiment with different gauge wire to get it right or bending the wire double even at the ends where it goes into the bleeds .
You will also have to tune the springs in the outboards , they may need lighter springs as they will open too slowly .
I agree with porting the intake .

Great advice, thanks all!  exactly what I was looking for.... anyone know a good engine builder in SoCal familiar with building Mopar setups like this?

[jordan]

I had a little trouble getting it to idle. Holley recommended to drill a small hole in the throttle plate to get more air past the idle transfer slot. Worked good for me.

[rikkitik]

 I have a VERY similar setup. 6 pack, Edelbrock (Hughes DPM), TF240's, SFT Ultradyne 243/247 .586/.594 108 lsa. I'm around 10.5" manifold vacuum. I strongly suggest the complete ProMax setup (metering plates, metering block, and rear baseplate). Their rear base plate has angled idle screws to make them accessible. I actually opened up the holes in the end carbs blades (they're already drilled from the factory). I also ordered blades for a 340/6, the holes are larger on th 340 carbs. The idle is very consistent now. ProMax jetting suggestions were not even remotely close (pig rich on my setup). I do use a dual channel Innovate wideband, it really helps a lot.
The OEM springs work excellent for me. I was doing 2300 to 6000 rpm, third gear jetting "pulls" when dialing in the mains, no hesitation/bog, or "coming in late" surge. Just a strong, clean pull up to 6000 rpm. Mine likes 22 degrees initial, 12 degrees mechanical on the ignition timing. 10.3:1 compression ratio (on California "gas").
One thing I found that was a great benefit, was to disconnect and plug the end carb vacuum lines. Drive and tune the center carb to perfection before moving to the end carbs. All idle mixture settings, and center carb, must be "right" first. The end carbs mixture screws not only affect idle quality, but also have an influence on the fuel transition when the end carbs open.