From personal experience the OD with the 3.55 is a good 'streetable' combo (I wish I would've gone 3.73 for the heavy late duster...and the next project will be 3.91's for sure).

With what you are asking headers, a 390 holley, dual exhaust, OD tranny, 3.55's, custom timing curve, headwork, bump in compression, and a 'medium cam' (like 268 max.) should get you close to what you want...

15 mpg is such a low expectation that you'll be pleasantly suprised at the results...

my '76 duster with the small cam, hyperpack, 3.55,OD tranny, dutra duals, etc... has pulled down up to 26 mpg in lean tune with carb heat, 15/21-23 with the 390 holley, and currently with the 600 cfm holley it gets about 14-15/18-20 (low numbers indicate 'the urge to merge' leadfoot lowend/highend is 'conservative' driving).


good luck in your decision,

-D.Idiot

[quote="Doctor Dodge"]A matched cam, carb and exhaust system is the key to a good performance.
For the street use, a small carb and low overlap cam has the most influance. For the track, low gearing and free flowing exhaust are important.
Coming up with a good balance of these 4 items can get you to your 15-15 goal with the quarter mile time being the bigger challenge.
How much does the car weigh?
DD[/quote]

My car is a stock 1973 Dart Sport,so I have no Idea what it weighs.But I am going with some lighter wheels,and may take out the back seat/replace the front bench with light weight buckets.

I am not so concerned with 1/4 mi. times,I just want it to be a fun grocery getter.

So I gather I should:
Offy intake
4 bbl. Holley 390
which cam???
what head work???
Best headers???
Best exhaust???

ICK!

D/W

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If it ain't broke, fix it!

Which carb do you reccomend?
thanks

I had a similar set up, except I was running just holley 390, clifford headers (true dual exhaust all the way out back) and manifold, 3 speed, bone stock everything else (2.76 one wheel wonder pig) and I got 26 mpg.

things are more extreme now, but I have been babying it since its a fresh rebuild

-dave

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what part of "illegal" is so confusing???

I prefer the Carter/Edelbrock AFB's. If you look carefully, you can even find a 400 CFM unit, aftermarket or OEM. I personally run a 400 CFM, but the guys here tell me they have had excellent success with the commonly available 500 CFM unit.

D/W

_________________

If it ain't broke, fix it!

I just got my car into the 15's. I still have some tuning. I got 16 MPG all highway miles about a month ago coming back from the Bay area Slant six meet. You can see my specs in the "virtual dragstrip" section.

I have to agree with Dan (he told me 2 years ago) that just a 4 bbl is not a "happy" set up. It is too much carb and too much frustration. You've got to have cam AND head work.

Personally, I think the bigger valves/port/polish/shave on the head made the biggest difference for the 4 bbl. The cam I have is still kinda small. The stock 225 head was designed for the 170, so there is a lot to be had in power.

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

I WANT a cam AND head work,but so far no one has made and suggestions as to what kind of head work I should do.I remember a person/place that someone on here suggested to send a slant head to get reworked....I know that is vague,I will try searching.

Also, my plans were to hop up the slant and have fun with it untill I am done saving up for my 5.7 hemi swap...but...I got the slant sickness

I want some good info on how to build up the slant internally to handle 20+ psi of boost.Is it possible to bullet proof a slant to push some serious h.p/boost?

Im thinking turbo through a MPI Hyper Pak......that would look kick ass

For headwork call Mike Jeffrey. 308/324-3576. I've had him do 2 new heads, freshen one, and will be freshening it again this winter.

_________________
Official Cookie and Mater Tormentor.

Thanks I think he was the one i was thinking of!

What do you do to your heads to make them go stale?

D/W

_________________

If it ain't broke, fix it!

"Im thinking turbo through a MPI Hyper Pak"....what happened to sensible, streetable, attainable?

You want recommendations then change the vision.

so,,,now you want cam recommendations for 15mpg/15 sec and turbo and SEFI and a carb ,,,and ,,,and?

Back up and make a plan.

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

Beat the holy shyt out of them on the dragstrip.

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Official Cookie and Mater Tormentor.

...well, that I kinda figured! Seriously, what kind of issues do you get with them after pounding the crap outta them?

D/W

_________________

If it ain't broke, fix it!

[quote="sandy in BC"]"Im thinking turbo through a MPI Hyper Pak"....what happened to sensible, streetable, attainable?

You want recommendations then change the vision.

so,,,now you want cam recommendations for 15mpg/15 sec and turbo and SEFI and a carb ,,,and ,,,and?

Back up and make a plan.[/quote]


The only vision that I changed was the one where I swap out the slant to put in a HEMI... DOWN THE ROAD.I was talking about a future build,not what I am doing with it now.NOT instead of my orignal plan,but after I save up.

Not to mention that a turbo is a streetable AND attainable route. As far as sensible,who ever said that building a slant was sensible

I think you should back up and read what I posted!