I've got a '65 Barracuda with a Slant 6 and lately I've noticed I've been getting really crappy gas mileage. Seems I'm only getting between 10 and 11 mpg when I could've sworn it was getting closer to 20 several years ago. As far as I can tell there isn't a gas leak anywhere, but I could be wrong. Could anything else cause a sudden drop off in fuel efficiency on this car?

Thanks,
kopper

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'65 Slant Six Barracuda
St. Louis Area Mopars (SLAM)

and the last tune up was??????
no fuel leaks??
could be a number of things,
from tune up to vacuum advance pod leak, to draging brakes.....

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65 Dart GT LA273 2bbl 904
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Old iron or no iron

Well, it *is* due for a tuneup, and that's one thing I'd considered. It's been over a year since the last one and I plan on getting that done in a couple of weeks. I only drive the car 50 miles per week, and that's all city driving with a lot of stop signs and stoplights on my way to work. But even so, it shouldn't be that low so I know something's awry...

Thanks,
kopper

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'65 Slant Six Barracuda
St. Louis Area Mopars (SLAM)

Is the engine running smooth at idle?
Does the car hot restart easily?
How does the oil look? Has the oil level increased any? Does the oil smell like gas? (The fuel pump could be leaking into the crankcase)
DD

Which carburetor have you got? The Holley 1920, perhaps? I've posted before about a Holley 1920 I once had on my '65 that exhibited strange behavior: The engine ran very well and had fine power, but was suspiciously easy to start and drive from cold (zero choke required, just hop in, turn the key and drive off without any stalling or gasping...even with the choke disconnected!) and the car was getting under 10 mpg. Turned out the brass seat ring that retains the power valve check ball, had fallen out of the metering block. Result was that the power valve was always WIDE open. I put the metering valve back together and restaked the seat ring, and things went back to normal (20mpg, choke and careful cold driving required).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Locking Gas Cap?????

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Well, I do have a Holley 1920 (almost 100% sure, because I had to get a rebuilt one a couple of years ago and had looked into, then quickly decided against, rebuilding one myself). I just looked at it, and the valve is not wide open... it appears to me to be closed, or as closed as it can get (while still being open a little bit). I moved the rod that leads to the thermostat and all appears to be working properly, so I'm not even sure what "ring" it is you're talking about, but all appears to be there, at least to my inexperienced eyes.

And I do need to pump it several times to get it to start, especially on cold mornings. It also stalls on me once or twice in the first few blocks from my house.

It's also due for an oil change, but suspicially is not low on oil (in response to Doc). It's also been rough idling a lot lately, like almost shaking the entire car. I noticed this again on my way home from work tonight. Back to the oil... When I check the level on the dipstick, it's actually above the Full line, even three hours after it was last driven. It's all the way up to the "F" on the dipstick, actually (about a quarter inch above the line). And I haven't added oil in months. It's last oil change was in August or September (I know, I know...), yet the oil level is above the full line? And yeah, I think I do smell some gas in the oil, so I think Doc may be correct in his assumption that the fuel pump is leaking into the crank case.

My mechanic's shop is a block from my house, and I plan on having him look at it on Monday. Thanks for the help!

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'65 Slant Six Barracuda
St. Louis Area Mopars (SLAM)

"rebuilt" or "remanufactured" carburetors you buy at the parts store are of notoriously poor quality and durability.
In order to see the valve I was talking about, you would have to remove the float bowl from the carburetor, which it sounds like you did not do.

Probably.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hard to start cold, oil level is "over-full" and rough idle when hot, all this points to a failed fuel pump dumping gas into the crank case.

Try pulling the PCV valve out of the valve cover and into the fresh air while the engine is running to see if the hot idle improves. If it does, fuel vapors from the gas/oil mix is getting sucked-up by the PCV and throwing-off the idle A/F mixture.
DD

If the pump is leaking, at least the inside of that engine will be REALLY clean....
Had a slant that I bought with the car, dip stick showed way overfill
and stank of gas.....
drained 6 1/2 quarts out , 4 1/2 back in.......
pulled the valve cover, man was that pup clean, got lucky on the
engine, still runs fine, guess it didn't get ran much that way....

_________________
http://imageevent.com/jeffc
62 D100 225 3sp lwb
64 D100 A318 727pb custom lwb
66 D100 A318 4sp lwb
68 D100 B383 727 swb
65 Belveder A318 727 4d
65 Dart GT LA273 2bbl 904
73 Scamp 225 2bbl 4spOD
Old iron or no iron