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Just wondering what the gas mileage would be for that engine. I don't know if it matters, but I have an 85 CJ7 with 35x12's...
 

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Well I read somewhere that for my Jeep (304, Quadra-Trac) in 1976 it was supposed to be 10 mpg but I swear I get better than that. I would say it is around 14, which doesn't make sense because the jeep is a lot older and has 33's on it.
 

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33's w/ 24# in 'em, 4.27's, 2 bbl Holley and Duraspark HEI/TFI = 13mpg average but I drive it like I'm 63 years old and built it myself. :D
 

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The Car & Track review of the '73 CJ-5 says their 304 got 11MPG.

 

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Now I am really curious to see what mine actually gets. Is the best way to run it dry put a known amount in it and run it dry again?
 

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In my '79, with 'Correct' axle ratio gears for the tires I have an some SERIOUS carb/ignition tuning I get 18 to 22 MPG combined.
Higher with more highway, lesser with more city, but I don't think it's ever dropped below 16 MPG.

We got 23 MPG on two lane highways on a short road trip this summer, lots of small town slowdowns, but not a lot of stops...

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Instead of running it dry and sucking up all the crap in the bottom of the tank,
Why don't you FILL IT UP, write down the mileage,
Then fill up again, and write down the mileage again.

Like everyone else does, between fill ups...
Unless your speedo doesn't work, then it's time to use your GPS, most of them have a mileage function if you remember to enter the data for gallons when you fill up.
 

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Now I am really curious to see what mine actually gets. Is the best way to run it dry put a known amount in it and run it dry again?
Actually I would fill it up (just until the pump clicks off), record the mileage, drive it until you are around 1/4-1/8 of a tank, fill it back up and use that amount to caluclate the mileage.
 

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I haven't ever computed it, but I think I am in the single digits; like 8 or 9 MPG. That is with a 304, T-176, 3.73(?) gears and 33X15.50 tires.
 

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I get 8 mpg in mine. With some jet changes and good carb tuning, I could probably get 10, but I really don't expect to get good gas mileage with the engine mods and heavy tires.
 

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12.5 x 33's (22 psi), 304/t176, 2150 carb. , 3.31 gears, I get 16.4mpg at 65 mph if only highway driving. I get 15 mpg mixed city/hwy.
 

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I don't have a gauge that is accurate, so I fill mine up when it I get that creeping feeling I'm about walk...
Just enter the fuel amount in gallons into the GPS and it spits out the MPG rating.

Close enough for me since the speedo isn't correct either with my tire choice.

I mostly drive KNOW distances, so I can double check the GPS, and it's pretty close, back and forth to work, back and forth to the farm, back and forth to the strip joint... I mean prayer meetings....;)

All pretty much the same circles, the only time I get strange mileage is when I go off road,
Then I'm down to 6 or 8 miles to the gallon, which isn't a big hoop for me since it's worth the fuel to go wheeling!

Do you guys have to idle a lot warming up before you drive?
That WILL effect your fuel mileage. Mine DRINKS fuel when it sits still warming up with the choke on!
The sooner you can get it moving, the better off you are,

And I gained about 6 or 7 MPG when I rebuilt the carb, upgraded the distributor, slapped on a CDI module and tuned the carb & ignition to work together,
Cut my warm up time to about 30 seconds, instead of the 5 minutes or more before it would sputter when I tried to drive it...

The guy I wheel with has an I-6 and he's getting about 21 to 23 since we did the CDI ignition, Weber carb and tuned it up, but he's OBSESSIVE about the tune, so it's as close to 'Perfect' as it will ever get for his vehicle.
He even gets 16 MPG when he's off road! (Hate that guy! ;) )

Having a tight engine will help TONS, so will getting the engine working in it's power band,
Tall tires and tall gears aren't going to get you any mileage,
Neither are really DEEP gears,

Getting the fuel you DO USE to actually light and burn helps a bunch.
You wouldn't believe what passes for 'Exhaust' most times!
I see a BUNCH of guys that are burning so rich they plug up my 'Rich/Lean' indicator (O2 Sensor) when we start out!

There are the half closed chokes,
The sucking vacuum leaks,
The half smashed shut exhaust pipes,
The plugged up cat converters,
The leaking carbs/fuel lines/vents,
The vacuum advances that don't work,
And let's not forget the guy with 200,000+ miles on the engine still trying to get fuel economy!
 

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And I gained about 6 or 7 MPG when I rebuilt the carb, upgraded the distributor, slapped on a CDI module and tuned the carb & ignition to work together
JeepHammer,

You helped me TR and complete the CDI Module upgrade on my '72 304. Thank you again! Jeep runs great, but would love to sneak out a bit more MPG. I have my timing advanced 10 degrees with plugs gapped to .045.

Any quick advice on tuning the carb or pointing me in the right direction?

I just put new 33x12.50x15 tires on it so not expecting this to help...I also have 4.27 gears.

I hope I'm not hyjacking this thread if so my apologies.

SC
 
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