Hi gang, been awhile.

I will be tuning up my brother's 83 Dodge shorty van in a few weeks and he has asked me to tweak it for better fuel economy.

Presently, the van has a Super Six (BBD) on it, 2 1/2 inch exhaust, a 727, and 3.2 rear gears. I have recurved the distributor and the van will get 18 MPG on the highway. The motor has been rebuilt with .060 oversize pistons and has a stock 72+ cam in it. The cam is about 6 degrees advanced.

I would like suggestions on ways to increase fuel economy and torque, if possible.

I have a one barrel intake and a Holley 1945 carb that looks to be in good shape. Would it be worth it to swap this on? The motor truly never sees more than 3,100 RPM, so I am not sure if I need the higher flow of a two barrel.

Would it be worth it to try a Holley 5200 staged two barrel?

Would swapping on my rebuilt head with the Ford 300 valves make difference in low end torque?

My goal here is to maximize fuel economy and low end torque, not build a high RPM horsepower motor. I have already removed the accumulator spring form the tranny and back the line pressure screw out as per the Mopar Performance free tranny upgrade suggestions.

Any tips would be greatly appreciated!

18 mpg is excellent for an '83 B-van with slant-6 engine. The 1bbl setup would likely worsen it. What kind of emission inspection is this '83 subject to?

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

No visual, and this is the last year for the sniffer. The previous owner yanked all the emissions stuff and to get the van to pass emissions I cobbled together a AIR injection system into a single aftermarker high-flow catalytic converter. Emissions are very very low now.

Would swapping to the big valve head or swapping on a Holley 5200 be worthwhile? Or should I be happy and leave good enough alone?

I know I might be able to bump the mileage up a bit by swapping to a lock-up 904T from an early 80s van (funny, I just sold one of those ) and installing the factory cold air intake setup, but I don't know if my brother will be willing to pay for that.

The thermostatic air cleaner would definitely improve mileage. The big-valve head would not. Holley progressive carb...maybe, with a fairly large amount of tuning.

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

The van is running a factory correct van super six air cleaner. When you say "thermostatic air cleaner" do you mean hooking up the heated air intake? I am talking about the cold air induction setup used on mid to late 80s vans.

Sounds like Dan says leave it alone. Any other input?

I'm saying duct the air cleaner's front snorkel to the front for cold-air intake. And yes, hook up the heated air intake.

You could do the HEI upgrade.

You could put in a lower-restriction exhaust system.

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

Dan is right--short of re-inventing the engine 18 mpg is pretty good for shoving what amounts to a sheet of plywood through space--a van is a pretty dirty aerodynamic (not) shape to push through an air stream. You might want to look at a thermostatic clutched fan--that will get you perhaps 1 to 3 mpg depending on what kind of driving you do (I am assuming that you do NOT have one now). They only cost about $35 for the clutch--

If you want to carburate for economy you may want to consider a Weber 32/36 DGEV--these are easily tuned for mileage while still retaining the 2nd barrel for power. They are not cheap when you buy them new. I wonder if you aren't already at the point of diminishing returns in that you are unlikely to get much past the 18 mpg figure without spending more than you can recover with improvements in gas mileage. Knowing exactly what your fuel/air ratio is will be a great help in eaking out more mileage....

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Slanted D150

I just took my '85 shorty off the road yesterday in ordrer to do the swap to HEI and a supersix combo part of a month long renovation. While I'm in there I'm repainting or replacing everything valve cover to tailpipe. My primary goal is to really simplify the engine compartment and layout and have already tossed a hundred pounds of dead weight off of it. I want to be able to take the valve cover off or pull the plugs at the drop of a hat instead of removing a gigillion rotted parts everytime. Even though I'm confident to gain a few mpg when its clean and finished, I'd gladly sacrifice those couple of mpg just to have an engine thats easy to service.

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GTO: "It's not too comfortable in here"
The Driver: "Yeah, It doesn't even have a heater...... It slows it down"
-Two Lane Blacktop

Thanks. It already has a clutch fan on it. THe Holley 5200 is the American copy of the Weber 32/36 DGAV. It even says licensed from Weber, Italy in the float bowl.

Looks like I have just about maxed this one out. Thanks!

There right about you doing about the max with your setup. But there is always room to improve even if its a lot of work.


To me ignition would be a real focus here, hotter spark from the electronics, and even experimenting with hotter plugs and timing settings. Just watch for detonation because pushing that big van can load things up on you.



A hotter thermostat if you have good enough cooling system to still keep it cool. Atleast a 190, and even up as high as 210 are used on newer cars just for that reason ( more effeciant burning of fuel in the engine).


I am not so sure that a bigger valve head want help. But it would have to be done right so that reversion did not cause any problems. A head that was reworked with newer, better style valves ( but still factory size), 5 angle valve job, with the ports worked too accomidate swirl and fuel mixture motion could be a big plus, then a little milling (more like a lot) to bumb the compression would almost be a given in the fuel mileage race. This could give a better burn in the cylinder, plus reduce pumping looses.


Have you looked into helping the body with its aerodynamics. It may seem like a big box, but so is big rig over the road trucks and they have been doing some pretty good stuff in this area that has proven to give better mileage. DO a search for "air Tabs" on goggle and you can find some info. Front air dams and other air directing parts can help.


Tuning the carb to a better state can help, and the Holley/Weber change might bring a little more if tuned just right.

A custom cam from someone that really knows what there doing can be helfull also. Alot has been learned in the past 10 years that can really go towards more power plus better mileage. Most of the time more power does turn into better mileage if its in the right RPM range.

A tuned header with tuned exhaust can make big improvement, but you got to think about the heat in the intake, you dont want to lose that.


Really it will be hard to gain much on highway mileage, but 2,3 or 4 more MPH can be a big plus with todays fuel prices. The around town, and cold start fuel mileage has room for the biggest improvements. When you add up the savings in all area's there can be lots of fuel savings. Documentation of all running condistions before starting to work on any thing will help so you know exactly when and where improvments, or reductions are made.


Jess

Van already has the 2 1/2 inch exhaust with a high flow cat and a high flow muffler. The muffler is a bit loud, so I will be looking for a way to quiet it down some.

Plugs are already at .045.

I am not willing to spend a whole lot of money on this since it is all for free, but going with what I have on hand and can get cheap from a boneyard, I will throw an old Mallory Hi-Fire coil I have on there, I could do the HEI swap, try a hot (210?) thermostat, get the cold air intake and the heated air intake hooked up, 45 PSI tire pressure.

If I spy some cheapo aerodynamic mods I could make I will try them. Air tabs look intriguing, but are a bit rich for my taste. I would rather get some epoxy glue and lexan from the local hardware store and make my own. If I could find some rear fender skirts I would put those on.

What tire size is he running on? How 'bout reducing the tire size to heighten your drive ratio and help lower the wind drag by dropping the body an couple inches.

Hotter plugs do not/cannot improve economy. What can improve economy is colder plugs: If the baseline (hotter) plugs are causing detonation, the colder plugs can "buy" some lattitude for additional spark advance before pinging becomes a problem. Going too cold causes trouble with spark plug fouling, though.
I just ran an experiment with my truck w/318 engine: I put in an Edelbrock intake manifold designed specifically for fuel economy (an SP2P; they don't make them any more), a 205° thermostat, and Evans Waterless coolant. Results so far are excellent; the truck's never run better than it does now, there's zero overheating and zero pinging, and I have never before seen 600km between tank-ups, but I did yesterday. Of course, this 318 has TBI fuel injection, so I needn't worry about heating up the fuel and causing starting/driveability problems. Things are different on that front with a carburetor, especially with a van.
Big-valve heads per se do not improve fuel mileage.
Dutra Duals.

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

Belly Pan should help aerodynamics.

Have you've done a distributor recurve?

A wideband O2 sensor to see what's actually going on.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I have done a recurve on the distributor, that is where I think most of the mileage gains are coming from.

I will see if I can find a junked conversion van with the fancy wheel moldings and an air dam in the front, I don't know about a belly pan though.

Thanks!