I was wondering what you guys have for carbs on your 400m's. I'm looking for good power, but mostly torque. As of now, I just have the stock 2 barrel, should I upgrade to a 4 barrel?

 

What else do you have on your engine?¿

 

I plan on just a fresh gasket kit and bearings, a set of headers and a mild cam. I just want a bit of oomph while turing 35's.

 

if changing bearings why not a set of high cr pistons? get a 650 cfm carb..

 

The main reason is because i'm on a budget, and dont really need a whole lot of power. The truck has a 4 speed standard, and 4:10 gears out back. I wanted to rebuild the motor, so I figured I would throw in a small cam, some headers.. I guess my main question is, would a 4 bbl make a huge difference? What would the fuel difference be?

 

Better. The primaries on a 4 barrel carb are smaller than the venturies on a stock 2V carb, as long as those are the only ones you open up! (putting your foot into it will open all 4 barrels and you can forget the better mileage lol)
Overall, it is a better setup and should have been offered in trucks, IMO...

650 cfm is a great carb for a 400 turning up to 5500 rpm. 750 is not needed nor preferred unless you have a super-built 400, and run in a lighter vehicle at the drag strip.

 

I have a holley 650 DP on my 400. I love it. There was an incredible change in power and mileage going form an edelbrock to this 650 holley DP. I was actually pretty disappointed in my 400 after i rebuilt it until i put the 650 on it.

I also have 4.10's but wit an automatic in a 79 f-250 4x4 with an edelbrock intake, headers, 8:1 CR and a small cam .484/.510

 

Did you have to re jet that holley for your altitude? I haven't played much with the Holleys but know they can make more power when set up right.

 

When i first installed it on the truck i put it on right out of the box and it was great..

I knew it could be better though, so i bought a jet assortment, accelerator pump assortment, and squirter nozzel assortment and carried all of those around with me for 2 months before i stopped tinkering with the carb. I have had the carb setup the same way now for awhile and it keeps me happy. The only thing i can recommend to you is to NOT ever run any 'octane booster' thru the carb. I did this once, and it royally messed up my carb. I thought it was a coincidence so i tried it again, and got the same problems.

Its a fun carb. The edelbrock was easy (so easy a caveman could do it) but the performance and mileage flat out sucked. The holley took a bit more tuning ( tuning you cant do as easily on an edelbrock) to get exactly where i wanted it, but it was worth it for the mileage and power gained.

I have the carb setup pretty lean right now when at WOT. I just thought about it and i had the carb tuned so tight that when i installed a carb spacer i had to retune the carb to get it back to what i was used to..lol..

 

Yup edelbrock performer and holley 650

 

Ok guys i am new on here i was trieing to get the introduction and lost it lol .my name is jason morriss. I have been a ford nut over 30 yrs . I own 3 and that all i want to own . Looking forward to talking with all u . Gaining knowledge and sharing .

 

FiTech, you will never buy a carb again......

 

I ran a Holley 670 SA carb on my 400, and it made a noticeable improvement over the stock 2-bbl, especially at the higher RPM. I didn't see any improvement in fuel economy.