72 Dart 225 ci 1 barrell Holley
I am getting about 11 MPG. That seems outrageous to me. The car has been sitting up for ~2 years during restore. This is what I've done:
New points
New condenser
New plug wires
New plugs
carb kit (had to play with float level)
New PCV
Timed 5 deg BTC
Idle air adjustment about 1.5 turns out

Engine runs great. Float level was off and causing black smoke. Dropped level and smoke dissapeared. Any ideas? I'm considering replacing carb with a non-holley brand. What MPG should I be getting? Thanks much

Does your vacuum advance canister work? Is this a winter mileage measurement? Is it all short trips, hwy...?

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou,
I have a small vacuum canister mounted on near the firewall on passenger side which does hold a vacuum. The big one down next to the radiator is gone. I did think of one possible screw up.....I set timing with vacuum hooked up. We just got it on the road couple days ago. All driving so far is in town. What do you think???? Thansk

Semi-random thoughts:
Keep your foot out of it!
Get those bodies and other excess weight out of the trunk.
A little more timing might help.
How many miles since the rebuild - mileage usually improves as the engine breaks in.
Check tire pressure, brake drag, etc.

I think Lou is refering to the vacuum advance mounted on the distributor. If the diaphram is shot (won't hold vacuum) it will have an adverse affect on your mileage.

Is your choke opening all the way?

Are your jets & power valves installed correctly?

11 is bad. really bad. depending on the gearing, you should be seeing more like 16 or maybe even 20 around town.

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My truck is a Frankenstein creation
Built from the dead carcasses of others
And brought BACK TO LIFE!

Timing curve and fuel mixture ratio need to be checked.

Retarded timing can be caused by a bad vacuum advance "pod " or sticky mechanical advance. (weights and springs) You can check this with a timing light, the mark should "jump" forward right when you crack the throttle, (vacuum advance) then slowly move to 30 - 35 dgrees as you rev it up.

Fuel mixture is harder to check, you need an exhaust gas analyzer.
You carb could have a loose metering block and / or a loose main jet. Did you check to see if the screws were tight when the bowl cover was off?

Also check the valve adjustment as well as tire pressure and brake drag as others have already suggested.
DD

For gas mileage their is very rarely one majic fix, but rather a bunch of little things. When was the last time you changed the fuel filter (especially important if your car was sitting for two years)? Are your tires fully inflated? Is dead weight out of your car (every 100 pounds costs you 1 MPG)? Are your brakes dragging? Is your e-brake dragging? Are you doing all short trips and not letting the car warm up fully? That will kill your mileage too. If your muffler blocked? Look into all these things, they will add up fast.

The choke is opening properly. I do remember the timing mark jumping around quite a bit while idling. Though I have vacuum, I will check the condition of the diaphram at the distributor. Is the power valve the part which mounts on top and has a spring covered shaft which presses a small red plastic lever? Should this lever close off an opening going up from the bowl to the overflow? If so, it is not closing it off. Could this be a problem? I have fiddled around with the float level, as it was too high and smoking like a chimney after installing the kit. When I dropped the level, the smoke cleared. I'm afraid that messing with the float arm that pushes the needle where the fuel enters the carb, is the source of my problem. Sorry for not explaining this more clear......Gary

There is no brake drag. New fuel filter. Tires are OK. No extra weight.

That stupid looking canister thing on the left side of the engine is a vaccum doickey that helps MPG? That sucks then, some of hoses are lying around doing nothing. Still getting 16'ish mpg(pretty good since I have to idle a lot at this time of year).

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My car may be slow to sixty, but at least it's been reliably slow to sixty for more than thirty years.

I dropped from 17-18 to 12-13 since it got cold around here. between the temps and that stupid oxigenated gas they have here in winter I'm bummin over milage also.

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Same here averaged 14mpg on a trip to Reno last week, upon my return to somewhat sunny So Cal mileage is back up to 18-19mpg.

My fuel mileage is still great and it's been 5*F all week. Choke adjustment and 93 octane gas are my secret.

Shiva, that stupid canister is either a vacuum reservoir, or a fuel vapor canister. Neither is there for fuel economy reasons, but if the hoses are unhooked, a vacuum leak will result in a lean mixture. Oh, and excessive idling is a no-no. Unless you are doing it strictly for heat in the pass. compartment, you should idle the car ONLY until it will kickdown, or thirty seconds, whichever is longer, even in arctic temperatures. I then drive the car VERY GENTLY (30 mph MAX) until the car reaches operating temperature. Why do I do this?

Idling in subzero weather is very hard on the engine. Idle it only long enough to get the oil pressure up and open the choke up. Then, bring the car to operating temp as quickly as you can. The best way to do that is to drive it gently. (Driving it hard will put excess strain on everything.) What happens when you leave the car to warm up? The choke stays shut for a longer period of time, putting acid in your oil and carboning the combustion chamber. The richer your mixture is, the more wear on your engine. So you want to lessen the choke as much as possible.

Believe me, this is better for your car than letting it idle. I have put 100,000 miles on my VW Van this way in the 6 years Ive had it, on a hastily rebuilt engine no less, and it is still reading oil pressure and compression within factory limits.

gwp, the jumping timing could be due to either broken advance weight springs or a worn distributor shaft. Time to take the distributor out and look at it IMO.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

what I meant by idling is waiting at stoplights, when it snows I have to idle a lot at stoplights and intersections. Most of the time when it's really cold I idle for 5 min., when I can I just drive. Unfortuneately when it get too cold just driving would mean that I spend about five min. starting my car over and over as I try to get it to move, but after five minutes of idling my car is very nice about moving(she's like me, doesn't like to much excitment the first five minutes out of bed or I get cranky).

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My car may be slow to sixty, but at least it's been reliably slow to sixty for more than thirty years.