Hello all, i'm 15 and just purchased a 1974 Dart swinger with the bulletproof /6. I just filled the tank up and calculated the milage and it was under 15 MPG..... not good for the ol' wallet. it is a bone stock engine with no mdifications whatsoever besides timing and new filters and fluids. I live on Gravel roads with lots of hills, so i know that doesn't help, but i would at least like some more MPG than that..... My dad is a certified mechanic so we have the knowledge to do about anything. I have looked all over this website and seen all kinds of tricks, but i was wondering what kind of mods could be done on the cheap (under $500)
Thanks for any help you have [/img]

Welcome to the site
The first thing I would do is a tune up if you haven't done so yet, new plugs, wires, rotor, and a good brass conductor cap.
Also check the choke for proper operation it should open up all the way when the engine is warm

There are many others but this should get you started good luck

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85 d-100 HEI 2BBl
06 Toyota Corrola

Isaac, welcome aboard.

The first item you need to get is a Factory Service Manual. They are available on line from various venders, so shop around for the best deal, it will be the best tool you can have in your tool box.

1973 & 74 were the worst model years for fuel economy in the US. The engines from all manufactures were strangled with new pollution regulations, and before the catalytic converter arrived in 1976, these cars were pigs.

Don’t despair, there is an easy and inexpensive fix for your car. While performing a general tune-up, one of the important steps is to check & adjust as necessary, the valve lash on your slant six solid lifter engine. Stock engines have intake set at 0.010â€￾, and exhaust at 0.020â€￾. The preferred method of adjustment is outlined [url=http://www.slantsix.org/forum/viewtopic.php?p=72139&highlight=#72139] here[/url], and can be found at the top of this “Engineâ€￾ page, labeled as: “Frequently Asked Questionsâ€￾, along with a lot of other useful information that makes for good reading.

The next step will be to advance the timing a wee bit from the factory settings. I don’t have the exact amount of degrees at my finger tips, so someone will chime in with the number, but for now, bring it up to 6 or 8 degrees BTDC. This should perk your car up, and increase fuel economy.

Others with this year car will probably jump in, and provide a few other tips, along with what they are running for timing, and getting for fuel mileage.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Before you do this step, you might want to check the main jet in your carb, if you have the Holley 1945 (1st year on the slant six), in 1974 the main jet was a #58 and more advance will make it ping bad since it's already leaned out on the street...if rebuilding it, replace the jet with a #60 or #61 and reset the linkage to the 1976 standards...then reset timing per above, this will result in a bit more mileage and a bit more power...

Stepping up to a 2 1/4" tail pipe wil also benefit this mod and add another 0.5-1.5 mpg depending on start stop traffic or highway.


-D.idiot

Welcome!

My 74 Dart Swinger suffered from the same low mileage with the 1945 Holley carb. I was able to get the stock setup up to 22 mpg with careful tuning. However, I did deviate from the FSM.

1. changed the jet to a #61 and installed a new float.
2. removed the EGR
3. installed a 2.25" head pipe and muffler with a 2" tail pipe
4. removed the OSAC and ran a line directly from the distributor to the ported fitting on the carb.
5. adjusted the initial timing to 12 degree
6. made sure the carb heat was working, replaced heat tube
7. replaced all the vacuum lines
8. ran high tire pressure 35#s
9. switched to 10-30W oil
10. fine tuned the idle circuit

Later on I made a many more changes that helped me get over 25 mpg.

1. installed a 1920 Holley Economaster
2. 0-30W Mobil 1
3. Recurved the distributor
4. Cold ram air induction
5. Installed a heat deflector under the carb
6. Installed an electric fan
7. Installed a HEI coil, CH410X cap, NAPA MO-3000 rotor, 8mm Summit wires, NGK platinum plugs gapped at .045
8. Rewired engine harness, I had many cooked wires.....and was not getting a full 12 volts to the 3 ohm 60,000 volt HEI coil.

Hope that 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

Wjajr: See I told you so...

Ted & DI know their stuff. Their lists will keep you and your dad busy for a little while.

Don't be afraid to ask any questions, we are here to help.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Thanks for all the tips guys, i'll make a run to the local parts store and see what i can come up with and post the results

I'd like to add,check the distributer advance mechanisnm to be sure it isn't seized,and the vacuum advance isn't blown(very common).

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V8?? We don't need no stink'n V8!!

bigslant6fan: If your vacuum advance diaphragm is ruptured, consult with Aggressive Ted before replacing it. He may suggest you use a different than stock part that will provide better fuel milage, and engine responce.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC