how would i get a least 25 mpg out of a 71 duster pretty much bone stock except the radio heck the car even has the original muffler on and no rust on the muffler any tuning specs or anything would help

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Dusters Rock

25 mpg average is a very tall order. You'll have to go well beyond a tune-up, but that's a good place to start. Tune-up parts and technique suggestions in this thread.

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

Tall skinny low-resistance tires, make sure your valves are adjusted correctly, use Dan's Tune-Up Kit recommendation, make sure your timing chain is in good condition, make sure your timing mark hasn't slipped, make sure the carb is functioning and adjusted correctly, make sure the timing is set correctly, or even advanced a touch, 2 1/4 inch exhaust all the way back, cold air intake setup, heated air intake setup, correctly adjusted and functioning choke, run a clutch or electric fan, don't carry extra weight, switch to electronic ignition (Mopar or HEI), use ATF+4 if you have an automatic transmission, only drive downhill. Even then, you might not get to 25 MPG.

What are the specs of the Duster? Motor size? Carb? Are you willing to swap cams and pull the head for some machine work?

aggressive ted has detailed info on his ride-- he drives a lot of miles daily-- that would be a good place to start researching ,Lawrence

Izzy Michaels,

Yes, you can do it, even with a heavy car like yours and mine. Yours might be a little easier since you have the better aerodynamic body style. A stick shift would help too....Mine is more like a brick, but with good driving habits and ignoring the temptation to light'em up at stop lights you can get to 25+ mpg or more on longer drives.
I have done allot of different things to get there. Doc provided allot of good pointers like the others have mentioned with getting the weight out of the trunk, valve lash, using 0-30 synthetic oil, synthetic in the rear end, keeping the tires hard, electric fan, cold ram air, etc., but the frosting on the cake that brings the consistent good mileage was a careful distributor recurve with a 11R VC-208 vacuum advance and good driving habits.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

The 70-72 Duster has none of the federally mandated crash protection the 1973-1976 A-bodies got cursed with, it is just a bit heavier than the 67-69 cars...so he has a 200 lb lead on your car without the drivers in it.
He also will have points so the first conversion to stabilize his timing is an upgrade to the mopar EI, then Ted's distributor mix can come into effect.
Also knowing if he's packing the 198 or 225 will also help a bit.

Assuming either engine and the carb is in good shape:
1) tune up will get it back in the groove, and probably be about 20-21 mpg average at that point-keep tire inflated, regular maintenance, etc...
2) switch to 2 1/4" tail pipe can be good for 1-2 mpg gain depending on driving habit and if the pipe was very restrictive.
3) switch to Electronic ignition/distributor, since your car has the eletronic voltage regulator and 2 prong alternator you are halfway there, this will help stabilize your timing and allow you an easier dial in for playing with Ted's recipe
4) after that you will be working toward some $$$ items to wring out the last of the mpg, swap to a manual tranny with overdrive/swap rear ratio to be 'kinder' for use with that tranny, etc...

most of the best time spent is in the first 3 area above,

good luck,

-D.Idiot

The Plymouth Owners Club recently published an article in their bimonthly bulletin reviewing the history of the Plymouth's gas mileage achieved during the Mobil 1 Economy Runs.

Starting in 1955 all runs were made with automatics.

In 1960 the stock Valiant finished 2nd in it's class at 27.5 mpg

In 1967 Valiant finally beat out the Rambler's 5 year streak for Top Gun of Gas Mileage.

Upgrades of 4speed OD, HEI, 2 1/4 exhaust, etc might take those Valiants/Darts to still better places?

Back in 1980's my 68 Dart GT with 3.23 rear got 26 mpg regularly in the summer with it's slant with 4 speed OD swapped from an 80 Dodge Truck. The driving was in hilly New England with traffic conditions not being the best.

I'm finishing up my current 225 1965 Dart project with 4 speed OD, HEI, 2 1/4 exhaust, some weight reductions, cold air/heated air intake, NKG's, Magnecor's, extended rotor, 14 inch wheels, 2.94 rear, manual steering, electric fan, etc. for some similiar driving in the spring with today's gas.

Has anyone got results for their type driving for above modifications?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Don
Thats cool!!! What was the published number for the 67 take over?
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

24.57 mpg which included ice covered roads, a firestorm, Chicago traffic tieup, etc. during the almost 2900 mile course

see http://news.google.com/newspapers?nid=1 ... 649,676326 for a summary at the time



I found elsewhere that it had a 2.76 rear

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

A few years back a friend of mine from MI bought a Florida 73 or so Duster, slant with 904. Drove it to the Nationals one year and got 27 or 28 MPG but that was pretty much doing 55 all the way from MI.

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

Some more thoughts........

I am running a 2.76 ratio 8 3/4 posi with Redline synthetic oil. The 904 has 404,000 plus miles and is stock, no changes just yearly filter and fluid changes.

It's a little harder to get good fuel mileage today with the gas they are making. I really had to do some fine tuning to match the fuel for consistent good mileage. Up here in the northwest, engine heat and intake manifold heat play a big part in getting better mileage. I am using a 195 degree Super Stat and a aluminum truck manifold with the heat deflector under that carb which helps warm up #1 runner quicker in the morning.
I also installed a electric fan which rarely comes on in the winter. I feel not having the fan constantly blowing over the engine and intake helps it to come up to temp a little faster especially on cold mornings. The intake seems to be a little more efficient at atomizing the fuel with the mods.
I also run carb heat from the hot air stove around the exhaust manifold.
SL6 Dan suggested using 0-30 Mobile 1 and a WIX 1806 filter for no knock starts and immediate 50 psi in the morning helps the engine right away.
Before the mods. it would take a twice as long before it would pull hard and was responsive to the slight throttle changes.

Hope this helps.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Can you tell me more about this Ted?

My '74 Valiant 4dr was probably pretty close to the same weight as your car.

Initially, with the stock '74 EI, Holley 1945, 2.76 gears and A904, peak for me was 19 mpg. This was with the noodle pipe that came on the car.

Then all heck broke loose, as I switched over to a Holley 390/Offy and Feather Duster 2-1/4" Head pipe.
DusterIdiot curved a distributor over the course of an afternoon, using a 9R governer targeting performance gains.
That set up got better than 23 mpg going down the freeway. Combined driving was still up above 19 mpg.
The 600 Holley on the stock engine setup netted virtually identical freeway economy, but the combined dropped into the 15-18 mpg range.

All aspects of this car are now so radically modified that they don't relate to your setup or economy goals. I get 19 freeway with it at this point, in search of ever improved E.T.

CJ

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Part of Tyrde-Browne Racing

In 99 I bought the 65 Valaint and swapped in the motor from my departed 69 Dart. I gained 2 mpg ....all highway driving.

The 65 is that much better aerodynamically compared with the 69 Dart.

I put a 5 speed in the car and a recurve EI dist ....2.25 exhaust and the car was at 25 mpg. .....with no fan.

Best/cheap gains are TUNEUP, 2.25 exhaust, distributor recurve EI.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Since we don't have a sticky on this subject, send me a PM for details on how to and parts used or do a search on distributor recurve.

To give you an idea the way my car drives and feels at low rpms is there is allot of power on tap and with a little more throttle both P225 60 tires will break loose with the 8 3/4, 2.76 posi. It is a temptation that I try to avoid but the SL6 from idle to 2000 feels like there is a 360 under the hood. It is very spunky and sensitive to throttle input. After 2500 rpm it feels like a SL6 again due to #56 jet I am running in the 1920 Holley Economaster. A bigger carb would help it to keep accelerating hard after 2500. With a #60 up to a #66 jet it will hit 90 mph at the end of a freeway on ramp.

A careful recurve provides excellent throttle response and power so I don't have to push the engine as hard which results in higher vacuum readings and better mileage. Doc describes it as driving with a egg under your foot. If the power is there I don't find myself pushing it.
The stock setup felt very flat, lifeless and pinged allot. I was happy to see 18 to 20 mpg.
With Doc's coaching and guidance the recurve really tapped the available power and my engine is no longer the slug that it was......
Now it has some spunk, a blast to drive and gets excellent mileage.

Reference: My car with me and a full tank is almost 3600 pounds (still has the bumper guards and a towing hitch from hell) checked at our local truck scales.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG