Who is BS'ing who?

[cuda67]

Wow, what stories are being told here about gas mileage. I have read with much interest the reported 12-18 mpg with 408 strokers and 360's, I say caca to this. What are you doing coasting downhill, never going over 30 mph putting it in neutral at every opportunity? My previous engine a 318 with a 280/480 cam, 600 holley, 904 tranny, 323 gears and a 3000 stall converter NEVER got over 11 mpg on it's best day, 18 mpg with a 408 BULL CACA. I now have about 250 miles on the new Mopar crate 360/380 magnum with a 770 Holley street avenger, Mopar M1 intake, 904 tranny, 323 sure grip and 3000 stall and the mileage is 8mpg not 12 or 15 or 18 as some people claim. I really don't care, if I wanted mileage I would have gone to a 6 cyl. I just like to put out factual information to other folks that may be interested or curious as to MPG in a certain drive train and engine and not fantasy. By the way my Ford diesel doest get 18-20 mpg either as some folks claim. (end rant)

 

[caferacerx]

driving habits are the single biggest factor in fuel mileage
how you drive not what you drive

 

[Demon 408]

Rant and throw caca all you want. But, the truth is my 408 Demon averaged 15.5 mpg on a 500 mile round trip This is highway mileage averaging 60 MPH, not stop light to stop light. I drove normal, no coasting and no slow starts, just a normal drive. It's a 4-speed with 3:55 gears, 950 Holley, TTI headers and 26" Nitto drag radials. Most importantly, it has a recurved distributor with vacuum advance and I know how to tune a Holley and set timing.

 

[TrailBeast]

318/904 2 barrel daily driver 18 per gallon.
No bs just a fact.

 

[demon seed]

Gas Mileage, what the hell is that. I burn up 2 gallons just starting the Beeatch:blob:ops:

 

[DFX 340 Duster]

Rant and throw caca all you want. But, the truth is my 408 Demon averaged 15.5 mpg on a 500 mile round trip This is highway mileage averaging 60 MPH, not stop light to stop light. I drove normal, no coasting and no slow starts, just a normal drive. It's a 4-speed with 3:55 gears, 950 Holley, TTI headers and 26" Nitto drag radials. Most importantly, it has a recurved distributor with vacuum advance and I know how to tune a Holley and set timing.

Entirely believeable.
My buddy had a 1969 383 Road Runner with a 4 speed and 3:55 gears. He could get 16 mpg on the highway by driving normally. I had a 1964 Dodge Polara with a bored out 361 big block (372 cid) 4 speed, Hemi profile cam, headers, aluminum intake, and a Carter AVS carb that i could squeeze 18 mpg on the highway just by driving like a sane person and staying out of the secondaries. Another buddy took his 1964 Fury with a stock 383, 727, and 3:23 gears and ran it out of gas on purpose. We then put exactly one gallon of gas into the tank, noted the mileage on the odometer and drove around town keeping the speed below 35 mph and avoiding as many red traffic lights that we could until it ran out of gas again. He ended up squeezing 16 miles out of it.
These test drives were done in response to the "Oil Shortage" of the 1970s.

I agree with CaferacerX, how you drive has as much to do with gas mileage as a well tuned car.

 

[plumcrazy704406]

imo, no matter what the vehicle is...............

if you have to worry about your gas mileage, you should get out of the hobby and take the local public transit.

ops:

 

[67Dart273]

OK, real world, no BS

After putting a stock 71 340 in my 70 RR "back then," it would routinely get over 17 on the highway. Headers, carbs varied between Holley spread bore (new then in early 70's) Quadrajet and Thermojunk

My buddy had a 74 Dodge 1/2T 4x4 short box, big BF Goodrich tires. Dual exhaust, otherwise stock, 360 2bbl. Routinely got 14.5. THINK how heavy and "non aerodynamic" that is. You're talking about 5000-5500 lbs

No, "big" small blocks won't do that "all cammed up." But something approaching the 340/360 factory performance cams sure will.

 

[rumblefish360]

First up, on your engine, the 280/480 cam is 238 @ 050 which makes it a poor choice for any kind of mileage. Good for a street machine though. Also, your rear gears (3.23) converter (3000 stall, LOL!) and the tire size work against you.

Secondly, a list of mileage items would look like;

Open air cleaner
smaller carb. 600 on a 360, 500 on a 318
Dual plane intake, AKA OE iron, Performer or LD4B for a 318, LD340 for the 360
Headers help, but dual exhaust @ 2-1/4 for a 318, 2-1/2 for a 360 max size.
Add a "H": pipe.

Add a MSD or equal like ignition and open up your plug gaps to .055 or better if you can.
Vacuum advance distributor!

Electric fan/water pump, less parasitic drag.

Trans;

no stall, stock 2bbl verter
Add a cooler and a deep pan.

Rear gears, HWY.! (LOL) and a reasonable tire size. 26 - 27 inches max height.

Follow those suggestions. My '79 360 in a 3800+lbs. '79 Dodge Magnum got 20 mpg's all day long with similar equipment. The MSD added about 2 mpg's. Tune that carb and then tune it again and again and again. Take note of how it drives going down the road and run it as lean as you can for driving. Richen it up well for part throttle and W.O.T.

 

[1wild&crazyguy]

driving habits are the single biggest factor in fuel mileage
how you drive not what you drive

that and 3000 stall convertors! lol !

 

[rumblefish360]

that and 3000 stall convertors! lol !

I just added that. Thought I did. Thanks!

 

[Mopar to ya]

Anyone who buys any older car, especially a muscle car, and is concerned about mileage is an idiot. If you want mileage, go buy a Prius or a Civic. You want looks and speed, buy a muscle car. I never checked the mileage on my Dart. All I know is it costs $30 a day to drive it to work and back.

 

[1968FormulaS340]

My Barracuda averages 10 mpgs with a healthy 340, 4 speed, 3.91 gears and a 26" tire.

I think some people post their best (steady speed on a long flat highway) and this throws people off.

 

[Abodybomber]

Boils down to overlap and tuning ability.Factory cams still sell for a reason.With a good valve job ,intelligent parts selection,high teens are easy.

 

[1wild&crazyguy]

my 340 w/.528 284* '112*cl' solid cam, headers, mild port job, single plane, w/750 holley 4spd, 3.73 gear... gets 15 mpg on the hwy, no vacuum advance either...just spot on tune, spot on shooters/transition tuning and air in the tires...could'a got a lil more if I added the vac advance...but dont care cause im in this for power...the rest is just a benefit of owning a mopar instead of a pos chevy.


things like 26* initial timing and full advance by 2k help as well...

 

[Abodybomber]

Solids work awsome,don't they Wild?Better vac, and driveability.Wide lobe centers help too.

 

[Mad Dart]

Never checked with my 410 4spd & 3.55 gears, solid flat tappet 262@50 1.6 rockers with about .620 net lift. I filled up when I left and topped it off for the ride home, worked fine every time!

 

[krazykuda]

I built a 68 Barracuda back in college and drove it between school and home and averaged 17.75 MPG on the highway checking it more than three times.

318 block, 340 cam, 360 1.88 heads, rhoades lifters, dual plane cast iron intake, Holley 600 vacuum secondaries, 7 1/4 axle with 2.76 gears, with stock exhaust manifolds and dual exhaust. Idled at 22 1/2" of mercury, I installed a 10.5 power valve and had a vacuum guage and could part throttle accelerate nicely and gently above 12" mercury. I would fill the tank up before getting on the highway and then stop for gas after 200 miles and check the economy.

After breaking three 7 1/4" axles, I switched to an 8 3/4 3.23 and got around 16 1/2 MPG. But that 3.23 sure grip with the narrow tires really went through snow great. Was worth the drop in economy for the better traction in snow.

 

[airwoofer]

My Barracuda averages 10 mpgs with a healthy 340, 4 speed, 3.91 gears and a 26" tire.

I think some people post their best (steady speed on a long flat highway) and this throws people off.

My worn out 340 fish (3.91, 26.5", stripped interior) gets 5-6 1/8 mi passes on about 2 to 2 1/2 gallons. Is that good or bad mileage? Maybe the stroker with a 830 will do better.

hehe:joker:

I am considering replacing the 5 gal race tank that site where a spare would with a stock tank. Will still need the elec pump. Substitute for milage - bigger tank, don't drive as far. The way I see it is these are hot rods, not econoboxes.

 

[SirDan]

First of all, to you people who say " if you worry about gas mileage get out of the hobby", are you denying financially less fortunate people to own a cool car? that just ain't right.

What about young guns in college? we shouldn't own cool cars?

and back on topic,
I don't get very good mileage with my 318 but, I have not done much to tune it. I think its possible with the right components and the right tune.

 

[needsaresto]

There are better way to build engines and produce a great motor that does both h.p and efficiency.

A zero deck engine will always give better mileage,as should a heart shaped combustion chamber.

Alcohol and water injection will raise your gas mileage as well,even on a stock vehicle. I just made a poor mans water/alky injection system that raised my Caravans avg city mileage from 15 mpg to 17.For less than $5 and an hours work.

It's not all in the motor either. You could be having a lot of convertor slippage at lower rpm with a high stall.

Rear gear ratio makes a big difference as well as tire size.

 

[cosgig]

When I put gas in one of the older cars available here, I don't measure my mileage in MPG, it's measured in SPG...smiles per gallon. I don't know what I get in any car to tell you the truth, I just put the gas in and go, when it's out I put more in. I know about how much $$ to bring or put in to get there and thats about all the thought I put into that subject!! Just enjoy the ride while you're in it...you could be driving a mini car soon enough!!! Geof

 

[inkjunkie]

EFI, OD with a lock up convertor (this way you can have the stall with out it killing you), course is means you might have to put a "foreign" trans in the car. My Fairlane with a mild cammed 5.0 and a T-5 got over 20 on the freeway when I drove it from LA to Phoenix....There is a member here with a 725 HP 572 Hemi with EFI that gets 14......might have to step out of the 1970's sooner or later....

 

[RustyRatRod]

With a properly tuned Thermoquad and decent street gears, mileage above 20 is entirely possible. Although I would doubt it on a stroker engine, I wouldn't be surprised.

 

[Abodybomber]

I have done low 20s in L.A. traffic,use a vac guage.62 mph,use common sense,laugh at the people in a rush.