440 right cfm

[mopower04]

so, i see alot of different choices for carburation on 440 engines, whats the best way to go? 4x4 truck, on and off road use. i'm looking at the holly 750cfm vacuum secondary. now i see alot of guys with 850's and 1050's on there engines, whats the deal with that? you'd think those things would be flooded out, but i wonder now if a 750 is too lean?

[crisser]

Originally Posted by mopower04

you'd think those things would be flooded out, but i wonder now if a 750 is too lean?

CFM is not about fuel. It`s about air flow. All carbs, when set up properly, won`t be rich or lean. You can put a 350 cfm 2 bbl. carb on a 440 and have it flood out if the jets are too large, float too high etc. But, it won`t have high rpm power cause it`s too small a cfm. You will base your cfm on how much your engine can flow. Ex., a 440 with a stock cam and stock heads vs. a 440 with a race roller cam and ported heads.

[Rigormortor]

Originally Posted by mopower04

so, i see alot of different choices for carburation on 440 engines, whats the best way to go? 4x4 truck, on and off road use. i'm looking at the holly 750cfm vacuum secondary. now i see alot of guys with 850's and 1050's on there engines, whats the deal with that? you'd think those things would be flooded out, but i wonder now if a 750 is too lean?

To run over an 800 CFM carb you just have big valve heads ported, and a cam with a lift over .550 also this is all needed for max rpm's.... There is a formula to figure out the CFM's on your engine, this will be good for stock, with more performance you can increase the cfm's. It is Max rpms' times cubic inch divided by 3456 so lets say you 440 with a max of 6000 rpms... 440X6000=2,640,000 / 3456 = 763.89 CFM's

Now this is at 6000 rpms.... a 750 would do fine.... you dont cruise around at 6000 rpms all day.

[rampage_82]

Also even with a smaller carb.. you will be able to rev higher than the formula, you'll just be pulling a vacuum, and not making as much power as possible....

[rumblefish360]

A 750cfm carb on a 440 in a 4X4 truck is a excellent choice and balance.

[BELVEDERE2]

Use a thermoquad! Ha Ha!

[hotroddave40]

I vote for the thermoquad also. They are very good and a 850 works great at all RPMs.

I hate dealing with holleys and fuel dumping on the intake when I change jets but I have to admit, I ran a 770 street avenger on my very mild 318 and it was fine, never bogged or any of that stuff once I got the floats and such right. I have that carb for sale now, if your interested e-mail me at
HotRodDave40 @ Hotmail.com

[crisser]

I take the carb off to change jets. 4 nuts, 2 vacumn hoses and the throttle cable and it`s off. Might be a little more work but, I don`t get gas all over the place.

[wilks3]

I have a Eddy 600 on my .060 over 440 with all stock jets and rods. Its the manual choke version. Mild Comp cam, HP stock manifolds with TTI x-pipe system. Driveability is excellent. Engine will pull hard to 5500 RPM and then tapers off to 6000 RPM. Even at that, with 2.76 gears, 28" tall tires engine will pull 5300 RPM wide open! Do the math, thats fast. I would think it would be a very good choice for a low RPM 4X4 truck.

[rampage_82]

Yeah a 600 cfm on a 440 is ultra responsive,, I just hate that whistling noise when you push it past 5,000... LOL

[wilks3]

If you play with pedal you can whistle Dixie. LOL LOL LOL

[cudabob496]

An 850 horse NASCAR engine uses an 830 cfm carb.

Anyway, you can make 500+ hp easy on a 440 with a 750 carb. At least a 750 Holley DP! Didn't like the 750 Edelbrock on my 440!

[mopower04]

sorry it took me so long to reply guys, took vacation to go to the michigan nascar race! anyway, i'm sure i'm going to go with the 750 now. i think that will get me the 500hp i'm looking for and be just right for street use. thanks much and i'm close to this thing running finally! cant wait! you'll be the first to hear about it and i'll have a video of break in! haha