How can I make my 400 Engine more gas efficient?

[elanmars]

There is always the alternative of getting a 2 barrel 383 or I've heard of 2 barrel 400s? true? I don't know what my gears are and I don't know how to find out-all I know is the car was originally a 318 and if I can get ahold of the owner before the guy I bought it from, I might be able to find out.

But if there's anything I can do that's cost effective, let me know. Getting an over-drive transmission is not cost effective right now. And I'm not very knowledgeable as far as fuel injection goes and how expensive that may be.

[68X426]

I'll say the obvious: air up and tune up. Fill up the tires. Air filter clean and large/open. Keep tuning the plugs, timing, jets, until it is just right. After that comes the spending of real money. 

[Ghoste]

Oddly enough, some of the best things you can do for your mileage are the same ones you'd do for performance.  Start with a GOOD tuneup.  Proper tire inflation, a clean car and all of those little things can go a long way.

[Sublime/Sixpack]

The way you drive it will make a difference too.

[Musicman]

Put a 6-Pack on it, and learn to keep your foot out of it... Great 2 bbl gas mileage when cruising, and 6 bbl power under your foot when you need it
Downside... the initial investment... OUCH 

[FLG]

Quick question.

Ive heard a 4 barrel on its primaries is more efficient then just a 2 barrel, unless you put your foot into it.

[elanmars]

^I've heard that too. When I had my '73 Charger, the 400 also had a 4 barrel carburetor and it got me 11-15mpg on average, a lot depended on city driving but that's including going 70-80 on the highway.

Right now my wheels are wimpy 14s and they're all pretty much different brands too!!

[Cooter]

Depends on the 4 BBL carb..Holley is roughly the same size all the way round, but a Thermojunk has dimes for primaries and Q-balls for secondaries...


A 400 Low comp engine isn't gonna get but so good a fuel mileage....Big Block V8 engines weren't designed for mileage, they were designed for power and torque....Remember when running those tiny primary carb's, that you might have to stay in them to make the same power you did with a "Square" carb....

[RD]

73 Charger 400 2bbl, 2.76 gears, 23 mpg highway, completely bone stock.

[Nacho-RT74]

73 Charger 400 2bbl, 2.76 gears, 23 mpg highway, completely bone stock.

[Cooter]

1974 440 "pig" engine, with 284 .484 Purple shaft cam, headers, single plane intake, and Holley Double pumper, with 5-speed 18-20 MPG Highway, About 7-10 MPG in town....

[Nacho-RT74]

1974 440 "pig" engine, with 284 .484 Purple shaft cam, headers, single plane intake, and Holley Double pumper, with 5-speed 18-20 MPG Highway, About 7-10 MPG in town....

compression?

[FLG]

I get pretty good highway milage with my 400 4BBL Thermoquad. On a 230 mile journey i averaged about 20mpg.

[Cooter]

1974 440 "pig" engine, with 284 .484 Purple shaft cam, headers, single plane intake, and Holley Double pumper, with 5-speed 18-20 MPG Highway, About 7-10 MPG in town....

compression?

Around 9.0:1..With closed chamber heads that were milled ALOT..

[Nacho-RT74]

so they were CLOSED CHAMBER made, and not born like a closed chamber LOL

[OttawaCharger]

On top of a good tune up...
make sure your vacuum advance is hooked up and working.
Also - check your cruising A/F ratio with a good meter to help you setup the carb.  You might be able to lean things out a bit

[BigBlackDodge]

What!

No one has recommmended the TORNADO!!!!!!!!

http://www.tornadoair.com/buy1/



BBD

[Nacho-RT74]

starting problems will make you inject more gas trying to start it up, so start it up quick will save gas.

So If you get some starting up problem:

http://www.youtube.com/watch?v=cY1YndLmbXQ

[BigBlackDodge]

Now thats funny!!!

BBD

[greenpigs]

Well make sure to clean out the car including the trunk. Try to find a cheap set of aluminum rims plus one for the spare. How is the alignment? Dunno about carb but I had a holley 500 two barrel that worked good on a 350. Find out what gear you are runing as you need a starting point. Then you could play with rear tires size to help with highway MPG. Also don't know what your budget is but headers would help.

http://www.summitracing.com/parts/HED-78030/

Then I think 2.5 pipes and decent mufflers are important, if it can't breath it will never get good mpg. These are not my first choice but for the money they flow enough to handle your current motor needs.

http://www.summitracing.com/parts/WLK-24214/