What MPG should I get from my 225 slant 6 with a single barrel Carter?

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fiberguy

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My car seems tobe sucking gas, especially on the highway. It seems I'm only getting about 12 MPG for a six cylinder engine with a single barrel carb. That seems too low to me. Can anyone give me some ideas on what might be going on. I have the stock 13" wheels, since I can't afford to change them out for 15" right now, new tires, new radiator, and have re-done all of the exhaust and fuel systems. Any suggestions? By the way it's a 64 Dart 4-door
 
Unless you have some low gears in the rear, you probably have a carb problem. With freeway gears (2.76 or 2.93) you should be getting at least 18 with an automatic and 20 with a manual trans. A lot will have to do with your driving habits too. First, check your compression and make sure the engine is tuned properly. Make sure the timing is set correctly and is advancing like it should. Once those things are set, a carb rebuild is in order.....especially if it's a Holley!
 
Check valve adjustment! Lots of people forget they need regular adjustment and that will kill performance and mileage!
 
fiberguy said:
only getting about 12 MPG------------ seems too low to me.
Click to expand...

THAT is the understatement of the year.

A reality check. When I first bought my '70 440sixpack RR, stock except for Edlebrock/ Holley 800 DP, cyclone headers, hang-on air, and 3.54 rear gear, and a LOT bigger 'n heavier than your car it would get.......

13.8 at '70 mph, and I wasn't all that careful driving it

One of those little slants in good shape should EASILY get over 18-19 on the highway.

FIRST thing to do (you have a GPS?) is check the speedo

Second thing to do is take a real good look at your driving habits, and how much driving is slow/ in town?

Third, would be to go for a thorough diagnostic tuneup. By that I mean do a compression / leak down test. Check everything you can think of, like is the exhaust restricted/ crimped, is the heat riser butterfly stuck?

How does the carb act? What does the tailpipe plugs look like? Oil consumption?

Even with small tires---many of these CAME with small tires, they had pretty high geared rear axles.
 
ok man im going to say this i sold my 64 4 door and i got 12 mpg when i uesd the big pettle lol now may bro tells me hes getting 33 mpg not im not sure if hes nuts but ive never seen a /6 get more than 21 with a light foot with a light foot mine got 18 good luck and mine had too much carb in it it smoked black bad when i got on the the gas hard
 
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