75/76 Dodge Dart /6 average MPG and improvements

Hey all. New to the forum here and not sure if this is really the right place to post this, but Im sure Il find out soon enough. Here goes...

Im looking to pick up 75/76 model Dart with a 226 in it for the fact that I cant really afford a vehicle I can only drive on weekends, but, you know, got bit by the classic car bug. With gas prices in my area reaching as much as $1.10 per Litre (thats about 0.40ish gallons) gas costs are a major concern, in addition to my lack of extra parking and need for a regular driver that Ive picked this car as the one Id like to buy.

Now Ive read a few threads about this before, but I was hoping to get some more concise information on the fuel economy of these cars, and ways one might improve that. Quite frankly, new to cars in general so I can use all the advise I can get.

Thanks in advance. Your all awesome.

just anecdotal story, but I once got 29 mpg out of my rock stock 225 /6 automatic, 66 dart convert. I did it on a trip on I-5, from Seattle to Bellingham and back. I have to add that the car had close to 300K miles on it, and the engine was so loose, I could spin the crank by the dampener with one hand (spark plugs in! LOL)

Good thing it was an automatic then...... A 3 speed and a small hill, and it might not be in the same place where you parked it!!!!

The slanty could get decent mileage on flat ground with little load. The 75/76 Darts are the heaviest though, they were pushing close to 3400 lbs toward the end of the A body production because at that point, people started getting interested in a quieter ride, air conditioning, power everything, etc.
The lightest A body would be the 63-66 Convertibles with a manual top.
Oddly, in 1976 as a fuel saver measure, Ma Mopar built 2 A body cars with fuel economy clearly in mind. They were the Dodge Dart Lite and the Plymouth Feather Duster. Both had lean tuned slant six 225 inch one barrel engines. Both had lightweight bumper brackets to save weight. Both came standard with aluminum cased 4speed manual overdrive transmissions and a 2.94 axle. They were actually EPA rated at 36 MPg highway!
Google it, you'll see that I'm not bullshitting.

I remember that. I actually talked my coworker into buying one of them in 76.

Yes , that was back in 1976 . It's a new world now and driving a 1976/77 car every day is a recipe for disaster unless everything is brand new . Especially in areas of bad weather . I drove a '64 every day for 2 years and after driving all week I spent all weekend fixing it . Any car/truck of that era was never meant to last as long as it did unless a complete overhaul/ maintainence is followed religiously . Just my $ 0.02

73 Duster 198 I get around 24-26

Yeah, with the terrain around here varying extensively between flat land and light hills, and the winters being Ontario winters, Il likely have to do plenty of maintenance. Any of you running your cars through the winter? What would be your first recommendation for someone in an area that has four drastic, equally back breaking seasons? My original question still stands, but so does my statement that I can probably use all the insight I can get.

I should probably give a little bit more back ground. I live in an area where Im centrally and very closely located to work, grocers and any other necessities. Im aware that there will be days, maybe even weeks that this car will sit getting fixed up, and thats not such an issue. And when it comes down to it, I have a (new) car I can borrow. This whole classic car daily driver idea stems from a basic interest in learning to do my own work on cars and further my knowledge in that as a hobby. the dart it self, as I said, is chosen based on the fact that it would be incredibly unrealistic to buy, work on and insure (daily or collectors insurance) that I also have to dump a ton of money into gas as well. Honestly, my first pick in car would have been a 68 Cadillac Fleetwood (feel in love with that one when I was knee high to a grasshopper) were daily practicality not an issue. Or a 78/79 Bronco. Or if I was really really keen on muscle cars and still unencumbered by budgets, probably something like the AMC Rebel. But as it stands, I have to mix my want for a really cool car with my need for practicality. As I stated in my original post, the Dart seems like a really good middle ground, and with less concern for authenticity, seems like it has the potential to be made practical, even almost practical by today standards. But thats just what I figure. Your all the experts, so keep the advice and thoughts coming.

MPG will be a balance of driving style, and vehicle configuration. Each physical item cascades on to the next one. 2.94 gear cars spin more RPM than they are comfortable with at 65, without the OD trans. The OD trans has the OD gear where #3 normally is, so the gear spacing isn't ideal (1,2,4,OD) and can lug a stock slant 6. There are taller gear sets (2.76 if I recall) but the expense is low end torque.

Best MPG on a near stock slant will come from a well TUNED slant 6. Carb dialed in properly. Quality ignition components (Consider HEI swap) Valve adjustment. Reduce parasitic loss (electric fan, synthetic fluids, modern tires at higher pressures, etc). Breathing upgrades such as air filter and low restriction exhaust. Add a vacuum gauge as a poor man MPG guide. Add all of the above, plus driving at a speed that keeps the engine RPM as low as possible without lugging the engine.

Best MPG on a modded slant is all the above, plus stuff like a shaved cylinder head to add compression, 2 barrel swap, cylinder head port work, headers, etc.

Thanks for the tips. Almost everything youve listed in on my to do list, with some urgency or another.

First and foremost, transmissions. Unless it needs work, I dont really think its worth touching till it goes. When it does start to go, Id like to stick something with an OD in, simply for the fact that I do a lot of highway driving in my spare time. Id go so far as to say 75 percent of my driving is highway. Could expand a little on the issue with OD or do you know anything worth reading on the matter?

Good ignition components and everything else you mentioned could be done to reduce parasitic loss are definately things I plan to do early on, if only for the fact that, for the better part, I think I could slip them one at a time into any longer maintenance session. In addition that, a 2 barrel carb is something I plan to tackle soon into it all too. Speaking of which, How would one mount a 2 barrel on anyway? Assuming the engine I get has a 1 barrel carb, I suppose Id need some sort of adapter, right? And Ive always been kind of curious, do you or anyone know what kind of benefits I can get from a 2 barrel swap? I understand one stands to gain some HP and MPG with that operation, but Id be really curious to know how much, I mean, if its another one of those cold-air-intake-gets-ya-1-extra-HP-and-a-quarter-mpg type situations.

The one thing I doubt Il be doing is machining work. But in place of that, I plan to eventually cobble a turbo together, which in its self is another reason not to increase compression, from what Ive read. If Im correct, a higher compression engine is less friendly with turbos than low compression, no? In any event, I only say turbo because Ive read from a few sources that gentle driving with a turbo set up at anything between 4 - 6 psi can actually net a noticable increase in fuel economy, and higher increases can yield nice increases in HP. A win-win, if the cost of turboing the engine isnt too bad, which I have read can be done successfully on the cheap with junk yard parts if need be. I suppose this ties into one more thing, headers are mentioned too. Headers are one thing I might do for the hell of it, but if I were to go the turbo route at some point, should I be factoring that into my choice of headers? I havent exactly done a ton of research on either aspect, much less how they correlate, much much less headers themselves but from what I have read, I get a feeling they correlate real good.

Thanks for the response.

If it's high MPG you want, the '75-'76 slants are not the best candidates. I bought a '75 Valiant Brougham brand new, and it was the only A-body that I really disliked. I traded a '68 Fury 318 that got 14-15 city and 18-22 on trips, for the plush, but woefully underpowered Valiant that averaged 12 and 15 mpg.

On the other hand, my son bought a very high mileage '69 Swinger 225 auto and used it to commute to his job at a ski lodge 40 miles each way. He got low twenties and usually carried one or two other workers on the commute. Mixed driving in summer averaged near 20. It had nearly 300k when he sold it, and the only major repair was a $100 transmission rebuild from a friend.

I would stick with the one barrel carb and do a couple Hot Rodder tricks. A header with 2 1/4 exhaust and a better air cleaner set up will help. Research light weight wheels. They reduce unsprung weight which saves gas and adds to power. Look for ways to reduce weight from the car. And of course tune it really good. I would also look for a A-body without power steering and A/C. Less problems- better mileage. Just my opinion, based on my experience

I had a 74 (?) 318 Dart 4Dr that once got 24 mpg whill traveling through Oregon and Northern CA on I-5. It was a black & white. ex City of Bellevue cop car. It had A/C, bucket seats, rubber floor mats, and no console. My wife was driving, which no doubt had something to do with it. LOL

Believe it or not a HHO system will help out. Put one on my kids mustang a few years ago and it got 43 hwy, it was a for banger though. Header and a two barrel manifold will definitely help out also.

The OD transfer has some wide ratios 3.09 first, 1.67 second, 1.00 third and .73 OD. Here's an article on the 4 speed.
4 Speed Transmissions transmission

The best thing you can do for /6 mpg is Tune it. 73 up has electronic ignition, adjust the gap, get new cap, rotor and spiro core silicone wires. Check to make sure the vacuum advance is working. Get a set of platinum tip plugs while you are at it. Make sure the carb is up to snuff, rebuild if not and make sure your choke is open at operating temperature. As you can afford it, run 2.25 in exhaust with a free flow muffler. That is the best place to start.