Daily driver setup

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713404spd

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Hello everybody. I just bought another 71 duster a few days ago and plan to make it my daily driver. I'm going to be more worried about fuel mileage than power but I would like to be able to keep up with interstate traffic. So far I am considering a factory exhaust manifold into a 2.25 single exhaust with a super 6 set up. I will be putting an electronic ignition on it. I have everything for a factory Mopar setup but I have had nothing but bad luck out of that system I will be running a 2.93 rear gear and I am undecided about the tire size. What cam grind and torque converter would be good for this? What ignition should I use? So far from what I've seen a realistic mileage figure is 20-22 correct? How much hp and torque should I expect? I am open to tips and suggestions and Please critique my setup if you see something wrong with it because I am new to the slant six world. Thank you for your time. Seth
 
Basics,first.Is your exhaust manifold cracked?Start with a basic tune up.Second,find out why you are having problems with your ignition.Trust me,you do not need a cam,these are built around gas mileage.My 72 dart had 150,000 plus on it when I sold it.I was getting 22 mpg then.Fix whatya got, its good stuff.
 
I havent installed the ignition yet. The car is disassembled and getting ready for paint so I will give it a good tune up before I put it in. When I said I had trouble with the Chrysler system I was referring to past cars that would always fry the orange box or the ballast resistor at the most inconvient times. Thankyou for the reply buddy!
 
sounds like a cool project. power wise i wouldn't expect too much out of the motor, being that it's a /6 and it's tuned for economy driving. It will do fine on the freeway, but it won't have the normal reserve power when you feel like speeding around another car. i would say that it will be a very nice daily driver though. good luck with it!
 
For mileage, I would stick with the stock 1bbl. I've had both as daily drivers and didn't get enough extra power with the 2bbl that justified the loss of 4 MPG over the 1bbl. The 2bbl carb is a better carb however....less troublesome. I've had good luck with the factory electronic ignition so that's what I've used. Second choice would be Pertronix. I'd keep spare parts for either system in the trunk. Stock cam and converter specs for a Van might be the way to go for mileage. Compare the posted charts or spec sheets for them to see what characteristics they have.
 
I got better MPG with the 2 bbl Super Six over the stock 1 bbl with my old 1968 Valiant sedan and seems to be the same with my 1967 Valiant coupe...

I'd recommend making sure the valves are adjusted corrected, go with the 2 1/4 exhaust pipe, and do the HEI upgrade as detailed over at slantsix.org.

There is some science to timing as well, I have my initial set to 8 BTDC right now but I'm not sure what the total is. I'm going to really dig into it after I get the HEI conversion done. Right now it's my daily driver so I can't tear into it too deeply on a weeknight.

valiant01.JPG
 
see i have to disagree with the induction...

i run a 600 holley on my car and get 20mpg on the hwy...

if your going to do a intake/carb upgrade go right for a small 4 barrel and offy intake...

these things like an RV style cam... low duration 200-215* @ .050, as much lift as you can get (.450 or so)

as for the converter you should get one matched to your build... you want one what comes in a little later than a stocker but not to much... like 1700 to 2K would be great....
 
cudamark said:
didn't get enough extra power with the 2bbl that justified the loss of 4 MPG over the 1bbl.
Click to expand...

4 MPG loss???? I picked up 2 MPG. Went from 16 to 18 with mixed driving. And I'm pretty sure my foot was a little heavier... ;)
 
Thankyou for all the replies. How many more mpgs would average with a med setup and an od 4 spd?
 
Mopar kid do you run a vacuum secondary carb? and how is your engine built because I think that would be alittle overkill for a relatively stock 6. What do you think about the 390 cfm holley carb?
 
Use the stock electronic ignition that you have.
HEI upgrade makes the ignition reliable.
The od and high rear will actually hurt your milage because of the drop in rpm's between shifts.
I would put a straight 4-speed in it or at least change the gears to 3.23-3.55 if you use the od.
Use the holley 1 bbl, super simple carbs that work and you will see 20+ mpg.
Just use what you have and keep tinkering, I have not seen a slant yet that got really bad gas mileage unless it was really out of tune.
 
713404spd said:
Mopar kid do you run a vacuum secondary carb? and how is your engine built because I think that would be alittle overkill for a relatively stock 6. What do you think about the 390 cfm holley carb?
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im glad you brought that up cuz it wasn't what i ment! (600 on stocker)

yes a 390 or 450 cfm vac secondary carb would be great on a stock to mild build... the reason i say go 4 vs 2 is because for near the same cfm air flow you have much greater control = better mileage!

on mine its a heavily worked motor i built... should be in the 13's once i get the drive-train bugs worked out... carb is a holley 600dp with mech secondaries... some day i'll try a 750 vac...
 
sireland67 said:
The od and high rear will actually hurt your milage because of the drop in rpm's between shifts.
I would put a straight 4-speed in it or at least change the gears to 3.23-3.55 if you use the od.
Click to expand...

:wack:

How do "gear drops" affect mileage? The gear spread is nearly IDENTICAL to the popular GM 700r4 transmission. Perhaps GM put millions of transmissions with flawed gear rations into cars? I don't think so. :tard:

The factory 36 MPG 1976 Feather Dusters had 2.76 gear ratios and OD four speeds. Care to explain why Chrysler didn't opt out of the OD or the freeway gear ratio?

Please share with us the source of your vast wisdom. :roll:

Also; If ANYONE local wants to trade a standard ratio 4 speed for an OD one, I'll gladly swap you. I need an OD for my Valiant. :D
 
713404spd said:
Would you recomend headers with the 4 bbl?
Click to expand...

depends on the headers...

hookers with a 1 5/8" primary are to big for most of not all engines but they are the closet we can get...

for stock to mild i would look into the dutra duals...

cliffords arn't worth anything... IMO
 
If your not concerned with squeezing every bit of hp out of a stock engine keep the stock exhaust manifold but run a true 2 1/4" single exhaust all the way to the bumper, and run a super six 2bbl intake w/the correct 2bbl carb so the choke linkage will work. If you wanted to get a little fancy you could lightly port both the intake and exhaust manifolds just to clean up any casting flash. If you decide to break out the die grinder (if you have one) you can also gasket match the ports to the head to make sure the ports in the head and the manifolds are lined up with each other.
From my experience the OD 4spd works best with 3.55 gears, any thing lower than 2.76 and it gets kinda doggy once your out of first gear even with little 25" tires. A healthy stock engine w/od 4spd and 2.93 gears in a fairly light car (around 3000 lbs) should get at least 25 mpg on the highway.
 
RabidScott said:
:wack:

How do "gear drops" affect mileage? The gear spread is nearly IDENTICAL to the popular GM 700r4 transmission. Perhaps GM put millions of transmissions with flawed gear rations into cars? I don't think so. :tard:

The factory 36 MPG 1976 Feather Dusters had 2.76 gear ratios and OD four speeds. Care to explain why Chrysler didn't opt out of the OD or the freeway gear ratio?

Please share with us the source of your vast wisdom. :roll:

Also; If ANYONE local wants to trade a standard ratio 4 speed for an OD one, I'll gladly swap you. I need an OD for my Valiant. :D
Click to expand...

Comparing an auto to a stick with the same gear spread is like comparing apples to oranges, you have the slip in the converter to help you out.

Have you even looked at the location were the original poster is located KY,
I am in WV you are either driving down hill or back up a hill.

With the od and the high gears you will be shifting constantly when going up the hills or leave in od and loose all hope of any gas milage because your foot would be in it constantly trying to make it up the hill.

Od work great where the roads are retively flat but when you add moderatly steep hills with high gears there is nothing to gain.
 
In west ky the hills aren't near as bad. My usual commute is a pretty flat 4 lane about 20 miles long at 65-70 mph
 
805moparkid said:
Cliffords arn't worth anything... IMO
Click to expand...

Really.....?

Jack Clifford has set several 6 cylinder world records. You ?

Zero....Thats what I thought.


If you want to keep some respectability, at least have some proof of what you speak. Otherwise your credibility goes down with every word you type. :wink:
 
RabidScott said:
The factory 36 MPG 1976 Feather Dusters had 2.76 gear ratios and OD four speeds. Care to explain why Chrysler didn't opt out of the OD or the freeway gear ratio?
Click to expand...

Feather Dusters and Dart Lites with sticks came with 2.93s from the factory. Autos got 2.76. They also came with aluminum 1 barrel intakes with a specially tuned carb and had V8 (318) size exhaust. Aluminum bumber brakets and under hood & trunk renforcement. I have the fender tag and build sheet out of one of those cars. Wish I could save it as it has the original drive train minus rear, was an originally bright red car with sport mirrors, 4 speed od car. Most, if not all the light weight parts are still on it but it got hit in the front, suspention is out of it, and it has a '67 Cuda on the roof :cry:

FYI It has a factory steel under brace trunk lid insted of the normal aluminum one.
 
Johnny Dart said:
Really.....?

Jack Clifford has set several 6 cylinder world records. You ?

Zero....Thats what I thought.


If you want to keep some respectability, at least have some proof of what you speak. Otherwise your credibility goes down with every word you type. :wink:
Click to expand...

yea and he has passed away... when the old man was there they had there stuff together!

the kid just let it all slide, quality, customer service, and so on...

and yes i know mark has them on his car, but thats becasue its all that will fit around his mods lol...

as said about them they dont make power, they just free up what the stock manifold would hold back...
 
805moparkid said:
yea and he has passed away... when the old man was there they had there stuff together!

the kid just let it all slide, quality, customer service, and so on...

and yes i know mark has them on his car, but thats becasue its all that will fit around his mods lol...

as said about them they dont make power, they just free up what the stock manifold would hold back...
Click to expand...

Your right. They dont make power. But arguably the quickest /6 car on this site runs them. But yet, they make no power. :scratch:

Do you actually think before you type ?
 
Johnny Dart said:
Your right. They dont make power. But arguably the quickest /6 car on this site runs them. But yet, they make no power. :scratch:

Do you actually think before you type ?
Click to expand...

as i said, being a shorter tube design, un-tuned lengths, as i said they will Free up hp that would be held back on a stock or other lower flowing manifold...

a tuned header such as a hooker super comp is far superior... with the effects of pulse tuning and scavenging at a select rpm range...

you dont have to agree with me thats fine... as you read in my first port that you quoted IMO... even with the hookers i think the tubes might be to big (1 5/8 primary/ 1.44 or 1.5 exh valve)... so when money allows i will be building intake manifolds and step headers to correct issues and to see where some power has been left on the table...

as for you freaking out on me thats fine, we just have different views... but you should take it to pm's and stop clogging his thread with nothing productive to add...
 
713404spd said:
Hello everybody. I just bought another 71 duster a few days ago and plan to make it my daily driver. I'm going to be more worried about fuel mileage than power but I would like to be able to keep up with interstate traffic. So far I am considering a factory exhaust manifold into a 2.25 single exhaust with a super 6 set up. I will be putting an electronic ignition on it. I have everything for a factory Mopar setup but I have had nothing but bad luck out of that system I will be running a 2.93 rear gear and I am undecided about the tire size. What cam grind and torque converter would be good for this? What ignition should I use? So far from what I've seen a realistic mileage figure is 20-22 correct? How much hp and torque should I expect? I am open to tips and suggestions and Please critique my setup if you see something wrong with it because I am new to the slant six world. Thank you for your time. Seth
Click to expand...

For a daily driver with gas mileage in mind:
Stick with the 1bbl. I like the Holley 1920
Stock cam.
2.93 gear.
Stock exh manifold.
2.25 exhaust,free flowing muffler.
Chrysler elec ignition.
Fresh Autolites,wires,cap & rotor.

Tune it up, and see if it likes a couple degrees of advance.
Between the new tune, and the new exhaust the car will run much better, with a seat of the pants gain. When I was playing with this same set-up, I went up 2 jet sizes, with the opened up exhaust.

But then again, I run Cliffords, so what do I know ?
 

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