Hello All,
I just found this site and hope it will help me with my project.
I've recently decided to build a 1968 Barracuda notchback into my next daily driver. My 68 cuda is now stripped down to a shell and I'm currently working on the body. My goal is to modernize the exterior and interior while keeping the simplicity of the early drivetrain. I am sick of these new cars accept for their good gas mileage. A lot good it does to save money in gas when all you do is have to pay tons of money fixing all the stupid electronics they slap onto these drivetrains.
I'm 46 and grew up driving and repairing my cars. These days I'm crippled with the new car's technology, thus I'm going back to the days of enjoying working on and maintaining my car.

Now the reason I'm here, about gas milage. I've read that in 76 they built a slant six (225) for the Dart Lites and Feather Duster that could get 24mpg city and 36mpg highway. Is there a way to rebuild my 1968 225/904 and 1975 8.25" rearend (I got this because I wanted the big bolt pattern to go with the BBP late model disc brakes I picked up for the fromt) to duplicate what the 1976 setup had.

I read that they had lightened the cars by about 500 lbs. so I plan on frabricating certain brackets out of aluminum and replacing some sheet metal with street quality fiberglass parts to do the same. Does anyone know what the actual weight was for the 76 lites and feathers?
I've also read they went with manual steering to shave weight and cause less stress on the engine as well.
So in a nutshell what can I do to my cuda to get this good mpg?

Here are is some of what I've found thus far.

THE DART LITE PACKAGE includes; a gas sipping 225 six cylinder further enhanced with a special cam and timing, aluminum intake, and mods for excellent gas mileage. An aluminum case 4 SPEED OVERDRIVE transmission. Aluminum lightened hood and trunk lid. Aluminum bumper brackets, front and rear. Light weight seats and carpeting without the padding. These DART LITEs were a full 500 pounds lighter than a regular Dart Sport, and were capable of GETTING 35 MILES TO A GALLON!!!
BODY : RARE parts (light weight hood,lite trunk, lite weight bumpers.
INTERIOR : The rear seat and the front buckets.
DRIVETRAIN: The engine, ALUMINUM OVERDRIVE 4 SPEED and 8 1/4 rear.

The Dart Sport got several special variants for 1976. In a tie-in with the American bicentennial celebration, a Spirit of '76 edition was released featuring white paint with prominent red and blue bodyside striping meant to evoke the image of the American flag. And with fuel economy becoming more of a concern, a special Dart Lite was released. This was a Dart Sport made as light as possible with an aluminum hood, trunk bracing and bumper brackets, an aluminum intake manifold on the 225 in³ Slant-6 engine for the first time since 1960, specially-calibrated carburetor and distributor, extra-tall rear axle ratio, and TorqueFlite automatic or the A833 4-speed manual transmission. The Dart Lite and its sister model, the Plymouth Feather Duster, were rated at an impressive 36 mpg highway with a manual transmission.

More about the Plymouth Feather Duster and Dodge Dart Lite
The Feather Dusters were made in 1976, with an aluminum inner hood, trunk bracing, bumper brackets, and intake manifold; economy carb and distributor calibration; large exhaust system; tall rear axle ratio; and either 3 speed auto or 4 speed overdrive manual trans.
Their gas mileage was great for their day, and even for the present, given their size: 24 city, 36 highway. Few modern cars of that size can claim this. With an automatic, gas mileage slipped considerably, to 22 city/31 highway - still comparable to modern cars. Very few were sold, partly because they had to compete with the new Aspen and Volare, which were in the same price class; and because the tall rear axle ratio took a serious hit on performance.

These pictures are of Richard Benner's 1976 Plymouth Feather Duster - especially rare because it is fully loaded. Along with the usual slant six engine and automatic, it has styled Rally wheels, vinyl top, vinyl bucket seats with a console and floor auto shifter, full carpets, and all the options.

Cheers http://cyberwerks.net/cars/cars.html

Dont take these ratings too literally or for fact. Even today there is an uproar about these ratings being very exaggerated at best. Its like those ads in the classified that say you can make $3000 a week at home, sure if you sell to everybody you talk to!

it certainly wouldnt be lighter on your wallet, but there are also aluminum slant six blocks, i think that would be a significant weight reduction
ebay Alm. Slantsix

The aluminum block saves you about 70-85 pounds depending on equipment. Which is certainly nice, but an aluminum slant-6 is certainly not a holy grail in a quest for gas mileage. One thing to remember is that with the aluminum block, you cannot increase static compression ratio very much at all without sacrificing head gasket seal reliability...

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

That block belongs to Doug Dutra? Nice

_________________
1983 Dodge D150 Turbo Slant 6
Carb. 4spd. 2wd.

That 8 1/4" rear adds alot of weight. I don't remember the numbers, but it is alot. It might be as much as 80 lbs. I seem to recall that the 7 1/4" rear is around 120 lbs, and the big one is well over 200 lbs. If you are interested, I have a 7&1/4" BBP A body rear I will sell real cheap. You can bolt it right in and use your big bolt pattern wheels. This is what was in the Dart light as original equipment. It would be a 2.70 or so.

Your project is a nobel one, but hard to pull off. The best I ever got out of my 225 Dart with essentially the same set up, was 29 MPG. The Dart is heavier, and not as aerodynamic, so that might account for some of the difference. Read through the posts here, and you will find alot of good ideas. Good exhaust, good gearing, keeping the weight down, good ignition, good induction, and good tuning, are all part of the picture. I mentioned water injection in an earlier post, and there was some talk about it. Some thought it was pretty much over-rated, but others thought it had possiblities. I think if the engine is built right, it can certainly help. It is so easy, and cheap, I hope someone will try it and report back.
Sam

_________________

My formula for good gas mileage is basically the same as Sam's: efficient engine operation, low weight, correct gearing.

If I were going to set up your car, these are the parts I would use:

(1) 225 engine running the 72-up stock camshaft, HEI electronic ignition with a custom curved distributor.

(2) dual exhaust with 2 inch pipes all the way back or a single 2 1/4 inch exhaust (less weight)

(3) a Holley 1920 economaster carburetor

(4) electric fan and no belt driven accessories

(5) tench inch drums up front (drums weigh less than discs, and if you are building and driving for economy you don't need the extra stopping power)

(6) A-999 automatic transmission. THese have a lockup torque converter and higher first and second gear ratios. The higher gear ratios allow you to run a 2.9 or 2.7 rear axle gear ratio to decrease overall RPMs

(7) 7 1/4 non-posi rear axle with 2.9 or 2.7 gears (lighter weight)

(8) skinny aluminium rims. 14x5 or 14x6 max. Aluminium is lighter weight and skinnier = less rolling resistance. Run a taller tire to reduce your RPMs even more.

(9) reduce the weight of the car as much as possible: bench seat- not buckets, space saver spare, no big stereo speakers, no tools in the trunk beyond a jack and lug wrench, etc...

Thats it!

You may want to try and adapt a lean-burn system from a later vehicle to your car. It may or may not help mileage, but it will give you another very real potential failure point in your ignition system (and carbuertion if you go with a computer controlled carb)

The drum brakes do have less rolling resistance than disk as the caliper is always in contact with the rotor, and not so with drums. This has been verified in tests. BUT, I don't think it is worth the compromise. I would instead go for aftermarket calipers and adapters that would be in better shape and lighter than old OEM Mopar stuff. The slider adapters get grooves in them that will cause the caliper to hang up and stick, and thus drag even more. I would look at the kits that are made to adapt to your drum brake spindles. The economaster really is a great carb. It would yield 26-27 MPG on a standard Duster on the highway. IF you can find one.

The fiber glass fender and hood will not save you too much weight. I know because I have done it. Stock, they are fairly rough, and by the time you have done the body work on them to straighten them out, you have added a fair amount of weight back onto the part. You can save more weight by changing to fiberglass bumpers if you can find them for your car. Then you must be careful not to run into anyone. Don't put that silly console back in the car. It weights about 20 pounds or so. Just go with a small modern console that is in every new car, and modify it to fit. Ot, make one out of aluminum. For that matter, you could replace other steel parts with aluminum if you were adventuresome. The mopar a-833 OD 4 speed is a very good choice. It will give you much better economy than any Mopar auto. My mileage went from 18-22 when I switched from a 904 to a OD 4 speed. . That is 30%!

_________________

Minor nit: The cam you speak of is the '71 to '80 unit.
Ermmm...alternator, water pump...? Or are you talking about unnecessary stuff like A/C and P/S?
No such a thing as an A999 for slant-6. The A998 and A999 are V8 transmissions. The transmission you're thinking of is the '81-up slant-6 A904, which has the wide-ratio gearset with lower first and second gears, which permits the use of a higher (taller, numerically lower) rear axle ratio without making the car dangerously slow off the line. Such gearing might even permit the use of a 170 or a 198 instead of a 225, depending on the proportion of city vs. highway driving and what kind of sacrifices one is willing to make in terms of acceleration to gain MPGs.
Further up the scale. The 2.76 and 2.93 rear axles were used behind the regular Torqueflites for many production years. The wide-ratio Torqueflite w/lower 1st and 2nd gear allow the use of 2.45s or even 2.26s (if you really, truly do not care how long it takes to get to 60mph and want your top speed to be limited by wind resistance).
Ummm...dude, what brand are you smoking?! Lean Burn never makes things better, only worse.
OK, now I see your point: Put in Lean Burn, because then when the car won't start, you get amazing gas mileage!

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

H'mmm. It's possible, but that seems like a high estimate. Also, while this particular thread is about fuel economy, remember that adding weight isn't necessarily a bad thing overall...especially when it improves the weight distribution of the car. But yes, obviously for fuel economy, light weight is where it is.
Guy by the name of mpgmike on http://mpgresearch.com claims to have set up a Duster w/225 and A833OD to deliver 40+ mpg.
Not to mention one of the most important factors in making mileage: Good control over the nut behind the wheel! (careful, economical driving)

Always remember to do the maths when contemplating any mileage-increasing modification, to figure out your payback time/miles. That way, you can steer clear of mods that will never pay for themselves.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Picky Picky Picky. Yes he will need a water pump and alternator, and I will concede that the cam is 71-80.

However, I do have to disagree about the slant six A-999. I have one that came out of a 1983 slant six powered van in my garage. At least that is what the underhood sticker said. What casting numbers should i look for on the tranny to confirm whether or not it is an A999?

Which underhood sticker? I can't think of one that would call out the transmission by its model designation like that.
Find the trans assembly P/N, which should be stamped (not cast) into the housing's pan rail on the left hand side, below the shift and kickdown shafts and levers. You'll probably have to do some degreasing and/or scraping to find it.

Here's what the factory parts catalogue has to say about automatic transmissions in 1982 and 1983 D-trucks and B-vans:

4058 384 B-D A727, w/LONG EXTENSION, B1,2,3 w/109"-127" W.B., D1 w/115"-131" W.B., D2,3 w/131" W.B., w/225 Eng., w/LOCK-UP VALVE BODY

4295 941 B-D A727, w/LONG EXTENSION, B1,2 w/109"-127" W.B., D 1 w/115"-131" W.B., w/225 Eng., w/o LOCK-UP VALVE BODY, Approx. 1-12-1983 (CALIF.)

4058 395 B A727, w/LONG EXTENSION, B1,2,3 w/109"-127" W.B., w/318, 360 Eng.

4058 395 D-AD A727, w/LONG EXTENSION, D1 w/115"-131" W.B., D2,3 w/131" W.B., AD1 w/106" W.B., w/318,360 Eng.

4058 394 D A727, w/LONG EXTENSION, D1 w/115-131" W.B.,D2,3 w/131" W.B., w/318,360 Eng., w/LOCK-UP VALVE BODY

4058 389 D A727, w/SHORT EXTENSION, D1 w/149" W.B, D2 w/149" W.B., D3 w/135"-149"-159"-165" W.B., w/318,360 Eng.

4058 388 D A727, w/SHORT EXTENSION, D1 w/149" W.B., D2 w/
149"W.B., D3 w/135"-149"-159"-165" W.B., w/318,360 Eng., w/LOCK-UP VALVE BODY

4058 385 W A727, W1,2,3 w/225 Eng.

4058 397 W-AW A727, W1,2,3-AW1 w/318,360 Eng.

4058 396 W-AW A727, W1,2,3-AW1 w/318,360 Eng., w/LOCK-UP VALVE BODY

4058 383 B-D A904, w/LONG EXTENSION, B1,2-D1 w/225 Eng.

4058 398 B-D-AD A999, w/LONG EXTENSION, B1,2,3-D1-AD1 w/LOCK-UP, w/318 Eng.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Ah yes, this would be Mike Holler. He is the guy that built me the turbo manifold. He is a pretty talented mechanical guy, and I would take his word that he got the mileage that he claims. I have his email address, and will provide it in a PM to anybody that wants to contact him.

Greg

ARRRGH! My pan rail is stamped 405883 7998 9687 which most closely correspnds to 4058 383 B-D A904, w/LONG EXTENSION, B1,2-D1 w/225 Eng. So this slant six 999 tranny I thought I had actually isn't! Grrr.

Vans got a little underhood sticker that called out the options the van was equipped with. Here is the one on my 86:



I could swear that the one on the van I pulled the tranny from said it was a 999.

When it comes to my present van and my former suburban, having a decent load improved drivability tremendously as opposed to it being empty, shifting was more on key, acceleration more solid and smooth, and suspension more stable. No surprize however since that is the basis of its design, to carry things, and it 'performs better doing just that.