I'm looking to replace my carb on 70 challenger 440 mag automatic. When I bought car it had a holley 800cfm double feed and pump with mechincal secondary. The carb is from the earliy 70's and I can not get the secondary to pump.I'm looking to install a new carb. Living in ohio I drive it couple times a week for maybe 5 month. No racing. It looks like most people say if you have a auto you should use a vacum secondary . Is a 800 CFM a liitle over size ? ? Would a 650 double pump and feed be to small ? Just looking for suggestions what others are using and happy with. Stock exhaust / 3.91 gears / stock tires/ edelbrock TM7 intake
thanks
Gregg

i like the large 850 [?] cfm thermo-quads. they have the 1 1/2" primary blades.
they require an adapter if you have a conventional square bore intake. possibly a drop base air cleaner assembly as well, depending on your hood under-structure.
others will have a different recommendation.
just my opinion, your mileage will vary.

I'm only about 25 minutes east of you and I run a Holley 770 cfm Street Avenger on my '69 440 GTX (4-speed). It was plug and play and I'm really happy with it. I had the Holley 670 cfm SA on my '68 383 and that worked so well and that's the reason I went with the Holley 770 on the 440. You can find lots of other carburetors but from personal experience I would give the Holley 770 Street Avenger a look especially with how and what you do with your ride. Will have to meet up at the DQ in Huron sometime, I have a Y2 Sunfire Yellow '69 GTX.

Mike

CLICK HERE FOR HOLLEY 770 LINK

Fix what you have. It is a simple carb and the secondary pump not working is simple.

Pull the carb off with fuel in it and put it on a bench, remove the screw and squirter and then push the secondary pump arm down slowly and watch hole where the fuel should come out, if the little needle check valve pops up and lets fuel come out look at the holes in the squirter to see if they are plug up, fix as needed with either a can of brake or carb cleaner If the check valve is stuck try squirting some cleaner on the top of it and try moving the pump arm a again, if that doesn't work use a needle to try and slied between the check valve and the carb and try and move the check valve left or right
let us know if you try that or not and if it works or not

You have a PM on this

I have read vacum secondary is better for a automatic.

I've always had much better luck out of Carter's than Holley.

Depending on your intake, a T-quad or an Edelbrock AVS2 or the Street Avenger would be fine.
For a mild 440, 650-770 CFM is fine; the smaller carbs will have better response at lower RPMs, where most driving is done; bigger carbs will make more power at the top end.
Vac Secondaries are better for street use; the mechanical is great for hammering the throttle off-idle, if the rest of the combo likes it.
Check your sec jet block to see if it has the feed provision for the mech pump; I ran into a non-working mech sec pump with a carb that was assembled from parts.
Holleys are easy to work on & fix if you just pay attention and are methodical.
I swapped a pretty stock 383's troublesome AVS for an Eddy 650 CFM AVS2 and the Eddy's a better carb; partly because it's 53 years younger, partly because it hadn't been messed with.
(When time allows I'll dig into the original AVS to see what's up with it.)

I have ran and worked on most all of the aforementioned carbs. Most are not particularly bad carbs, but there is a better choice out there today. The Street Demon is the absolute best out-of-the-box street carburetor for mild to stock engines that I have ever ran. Strong statement, I know. But I have ran enough of all these different choices to feel confident in that statement. You would want the 750 version on a 440. And I have always used the black center model.

If you haven't tried one of these, don't knock it till you have.

'Our look at the Street Demon was more involved than a simple show and tell. Part of our evaluation was a real drive-time evaluation. Our warmed-over engine featured a mild 360 wearing headers, duals, a ported Edelbrock Performer intake, and a TQ carb. The TQ was an 800-cfm unit, nicely tuned and perfectly functional. What we wanted to see was whether the Street Demon lived up to its "ready to run" claim and delivered the street performance we'd expect. The Street Demon bolted in place of our existing carb in minutes, with an Edelbrock carb linkage adaptor allowing for an OEM-style Mopar throttle-linkage/kick-down stud. We swaged a 38-inch flared fuel fitting to mate with the factory 516-inch fuel system of our vintage truck and plugged in the required hose connections for the PCV and vacuum advance. Our TQ kick-down linkage required adjustment to meet the square-bore position of the Demon carb, but other than that, the Street Demon was an easy swap for our factory spread-bore carburetor. With a square-bore 4150 flange intake manifold, the installation would have been even easier. With a turn of the key, we had it fired.

Ready to run it was, as the only adjustment required was a twist of the knurled idle adjustment screw to bring us to a 750-rpm idle. The following clandestine WOT speed runs showed that the carb was truly "ready to run." Off-the-line response easily overcame the 3.55:1 peg leg from a dead stop, bellowing impressive smoke through the neighborhood. Through the gears, the carb pulled clean, leaving us nothing to complain about. After the install, I had a four-hour return drive home and hit the road confident that the Demon would get me back. I have to confess that my intent was to bolt my sweet TQ right back on after testing the Street Demon. The proof is in the driving, and this new carb is here to stay.'

www.motortrend.com/how-to/street-demon-750-carb-review

www.youtube.com/watch?v=oAhdCRixqqw

Plenty more tests and reviews are out there. I have installed a half dozen or so and I have been happy with every one. But as I said, these carbs work best on mild and stock combos. Hotter engines would benefit from one of the myriad versions of Holley's 4150 platform.

X2…Holleys are simple and as Cab says above it’s more than likely the pump diaphragm or the check valve below the back squirter nozzle or possibly the little orange “umbrella” check valve underneath the pump diaphragm may have deteriorated…give it a go, easy peazy

Thanks all. I'm going to work on it this weekend

All of the above plus one more obscure possibility. Many years ago I had a new one right out of the box that wouldn't pump. It had a bowl gasket with no hole for the pump passage. The bowl and the metering block had both left a mark where the passage was so i just drilled the gasket. Problem solved.
.
Edit: because I just remembered another one. The horizontal passage in the main body was not drilled quite far enough to intersect the verticle nozzle passage. Needed drilled about 1/8" deeper

I think the problem was low fuel in bowl. I adjusted float level but now gas is leaking under adjusting nut. I have been seaching internet for new gasket but have not found them. Does anybody have a part number for them or where you can get them ?
'

Every rebuild kit - you should always have spare carb gaskets - will have them; or Allstate Carburetor in NY, or just Google "carburetor parts" to find someone nearer to you.

I'll second allstate carb.

https://allcarbs.com/product/holley-needle-and-seat-gaskets/

Here's a few. That's why I like Holley carbs.....parts are simple to find. This was a 2 second Google search

https://www.google.com/search?q=hol...53j1j15&sourceid=chrome&ie=UTF-8