interesting. this is the first i've really read this. i daily my car til the snow falls/salt comes down and i do lots of short trips because i live in the city. is this a common known thing that they just get bad gas mileage on short trips? i know on the highway i steady get 20-23mpg in my slant six (dont know the gears off the top of my head) but in the city for short trips im getting 12-15mpg and i just keep assuming something is wrong with the car, but those short trips are often less than 30 minutes. and i drive that car like an old lady going to church to make sure everyone can get an eye full so im definitely not heavy on the gas.
How do i make my mopar a daily driver??
- Thread starter Hansen
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TrailBeast
AKA Mopars4us on Youtube
It's normal for fuel economy to be lower in town because you use more accelerator pump shots and intermittent higher loads in town.
On the hiway you pretty much stay at a stable RPM and load.
Milne get drove every nice day, weather permitting.I'd rather drive a classic that gets 25mpg hiway than a new POS that gets 30.
I’d be ecstatic if I got 20mpg instead of 11.7 which isn’t horrible for a 500 mile round trip to the nats running 70mph
City milage depends greatly on how much time is spent idling at stoplights, and similar.
I've logged trips back from a garage I rent a couple miles away and frequently more time is spent at a standstill than moving.
Even when in good tune and stock set up, the larger engine will drink more fuel when idling.
Add to that many of the v-8s are hot rodded and have by nature poorer idle efficiencies, fuel consumption per minute of idling gets even worse.
A slant six can get pretty decent milage.
TrailBeast
AKA Mopars4us on Youtube
I was getting right at 17mpg on the hiway with a basically stock 4 barrel 318 and 904 transmission at 75-80mph.
When I went to the 5.9 Magnum with a 42rh overdrive trans that went to 25mpg on the hiway at that same 75-80.
I went to a bigger cube motor, but bringing the RPM's down on the hiway made the difference.
A 500 RPM reduction on the hiway is 30,000 less cylinders filling with fuel in an hour of driving.
That's a lot of fuel.
rustytoolss
Well-Known Member
What do you think helped the most in MPG/ the 5.9 engine (lower RPM) or the A500 overdrive ? When your on a fixed income fuel mileage is important. A vehicle that sucks fuel like a pig..does not get driven much.
People say "smiles per gallon" but I guess they have more money to buy more fuel, someday they may not be able to spend as much on fuel...then they may change their minds/or not.
TrailBeast
AKA Mopars4us on Youtube
Lower RPM due to the A500 overdrive for sure.
If for example I were to put a stock 904 in the car the MPG would drop like a rock.
Keep in mind that that kind of MPG is ONLY out on the open road and in OD.
/6 Matt
30 Degrees Crooked
Sounds like North Carolina winters. You want to know how to make a carburetor just as reliable as fuel injection? Take the time to set the choke correctly and then drive it every single day.
Seriously that's it.
Take it from somone who's done it. The more frequently you drive old cars, the better they run. When you let them sit and drive them once or twice in a several week period you begin to have all kinds of driveability problems as well as age related (usually electrical) issues crop up.
rustytoolss
Well-Known Member
So using a 318 instead of a 360 should also help MPG . (I'm past the big need for HP)
TrailBeast
AKA Mopars4us on Youtube
One would think the 42 less cubes of the 318 takes less fuel to fill the cylinders, but the 318 might have to work a little harder than the 360 and offset that some.
Generally speaking the 318 would probably use a little less, but I don't know if the amount would be worth the change.
Tune is probably where you could get the best MPG possible, and vacuum advance is a big part of MPG tuning.
Just for information I run 18 initial, 34 with mechanical added and with vac advance added around 52 degrees total. (most of the time at around 5,500 feet elevation)
Generally, the more timing you can get in at all throttle openings the more available fuel gets burned and therefor the more efficient the MPG is.
BUT, it's a fine line before you get into preignition and possible engine damage, and this is why an EFI system is better at deciding tune than a lot of people can tune a carb.
Obviously just my opinion.
My experience with 5.2 vs 5.9 Magnum engines in my family's many Dakotas has been that the 5.2 with 3.55 gearing gets about 3MPG better than the 5.9 with 3.92 gearing.
How much is the displacement and how much is the gear is anyone's guess.
How much is the displacement and how much is the gear is anyone's guess.
In the late 80's I daily drove a 70 Dart GT with a .030 318, topped with 340J heads and cast iron intake, running a Thermoquad, no choke in temperatures ranging from 90 above to 35 below zero. Only left me stranded once, after the carb iced up on the highway and I ran out of fuel about 5 miles from town. Even had decent heat after I replaced the heater core, fuel economy wasn't great, I never actually checked, but probably in the range of 12 to 14 mpg around town. I plan to drive the 75 Sport as much as possible, year round once it's together, my current daily is a 30 year old Bronco, while it is equipped with EFI from the factory, it has about 175k miles on it and has been dead nuts reliable for almost 2 years now. I have had new cars, enjoyed them a great deal, but find older stuff so much more fun to drive. Just a personal preference.
How was the thermoquad compared to holley and edelbrock?
It worked pretty well for the most part, I don't know what it came from, I bought the car as an incomplete project. On the really cold days I had to pump the accelerator a dozen times or more, didn't help that I used an open element air cleaner all year.
I didn't have anything to compare it to at the time, ( Holley or Edelbrock), but I did compare them on a 360 Dart I had years later, 670 Holley Street Avenger vs 750 Edelbrock and found the engine liked the Eddy better, but I had also put a good deal of tuning time into it, less so with the Holley.
thats what i've heard eddy is more relaible, but holley is more easy to tune? thats probably why they sold the cars with carters/eddys back in the day.
Your hearing a lot of nonsense speculation.
The tuning needed for a stock engine is different than tuning for a modified or racing engine.
Many of the aftermarket carbs sold today have manufacturing and production compromises and none are tuned to the specific engine combination and vehicle. Holley, Rochester, Carter, Stromberg all supplied production carburetors to Chrysler in the 60's and 70's. The first three all came up with versions for emissions control requirements too.
The 4150/60 Holleys and their 2 bbl, and larger 4bbl cousins for various reasons became the most popular for racing. Doesn't make them better for your application. It doesn't mean there aren't Holleys that are turds.
Keep your battery on a charger
and you might get away with this for daily driving if you only drive in the country.
This could be part of your idle problems. If the ammeter is showing discharge at idle - that will be a big clue. Starting and idling is going to run down the battery with that pulley combo. It's not turning the alternator fast enough at 600 or probably even 800 or 900 rpm...
I have the stock pulley from my powermaster alternator but the crank pulley and the waterpump pulley is used. Hope this will be alright.
Was afraid to disagree due to the fact that you sound very aggresive towards me on most of my posts. but i have already checked the battery and it's working perfect. Thank you for any help you have given.
Update: been driving the dart for a few months now and it seems very good. I switched the PCV valve to run into the air filter instead of the throttle body wich seemed to pull false air and making it very lean, upped the jet size to 71. and its been alot more easy to start. Electric choke also works fine still some fine tuning to do on the fast idle screw.. but all in all i have no worries on the car to let me down. so to anyone looking to make your mopar a daily driver: Drive it ALOT, then fix/upgrade and tune. thanks for all replies.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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That will not support it's design function.
and so your engine will tend to gunk up, and the oilpan will accumulate water, which is the natural byproduct of the combustion process. The water will settle at the bottom over time and be the first thing your oilpump sucks up.
Not having a working PCV on a carb calibrated for it will mess up both the idle circuit and the low-speed circuit.
In my opinion defeating the PCV system on a DD is a foolish thing to do. Given time, your engine will destroy itself. In Norway, probably sooner than in a warmer drier climate.
A properly functioning PCV system is your engine's best friend.
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