Mileage question

Forker

Forker

Senior Member
Yesterday I went on my first club drive that all in all for me, garage back to garage, was about 100 miles (assuming my odometer is accurate). I had gassed up the night before so I had a full tank gas starting out. I had heard I should get 17 to 18 mpg, although I've never checked it.

Well, I didn't get a 100 miles out of a tank of gas or anything close to 17/18 mpg and ran out of gas. just short of getting back home. My gas gauge read -0-, so it didn't lie, even thought I was thinking it was when it hit -0- long before I thought it should.

My car is a 1930 Phaeton and the only Phaeton on drive, one of the members commented that he had a Phaeton and it also got poor gas mileage. The only thought I had about that irony was that maybe the open windows created much more drag and thus poorer gas mileage...although I think that's too simple of an answer. Other than the poor gas mileage, I also had a little leak on my water pump and added some water when we stopped for lunch...it was a large quantity of water btw.

Any thoughts on why my mileage was so bad and I'm not all that concerned about the mileage as I am to the fact that drive leader was doing so much better he never needed to consider gassing up and I certainly needed to.
Thanks
george
 
Was your tank really full or did the gage show full?Check the water pump nut if stock unless its a leakless version
 
The tank was full, I topped it off.

I had tightened the nut, but just checked it again and there was room to tighten it some more and I did, later I'll drive and see if that helped.
Thanks
 
George, there are many things that could contribute to this. while your theory of the open windows is plausible, your vehicle is also lighter, ...and my personal experiences have not shown this to be a cause.

With regard to your fuel economy issue, the first place to look is efficiency with the carburetor itself. Since I do not know the type you have, I will speak in generalities but was the GAV opened too much creating an excessive rich fuel condition for the engine? Leaning this out (twist to the right) can make a huge impact. Also, is the carburetor rebuilt properly (correct float level, throttle shaft leaking, and jet size)? Compression ratio is also a large contributing factor. Low compression either from worn piston rings, leaky valves, or a worn or incorrectly ground camshaft can also be a culprit. Hope this helps you pinpoint your issue.
 
Where do you keep the spark advance lever ---too retarded uses more fuel.
where do you keep the GAV? ---too open uses more fuel

I usually run full advance, gav closed below 40, 1/4 below 50, 1/2 over 50 with ethanol gas, with regular gas I can keep it closed all the time, have averaged 23mpg at 60+ mph on a trip, about 20 with parade and local driving, the plugs burn clean, very light tan ---I don't worry much, but 20$usually gets me 100+ miles

To confirm my mixture settings I ran my car on the inspection emissions dynamometer, the Gav settings I use give 1-2% CO on my car --since model A isn't in the database I ran it as a 1998 Honda civic --I could make it pass (NJ emission inspection)at the specs for the honda, but it was too lean to drive on the road at those settings
 
Thanks everyone

I run my spark advance all the way down and my GAV turned back a half turn.

Brent my only reason for the open windows thought was that the only other guy on the drive who said he had poor gas mileage was the guy with the Phaeton, which he wasn't driving yesterday...he was driving his coup, which he said got much better mileage. My 'windows' thought was just a guess, knowing they say in today's cars you get better mileage running a/c with your windows closed then no a/c with your windows open. With all that said, the difference seems too dramatic to be just the windows issue anyway.

I will take everyone's advice and see if I can make some improvements.
 
Three years ago I took my 28 Phaeton on a 600 mile trip and averaged 22 MPG on the open road with few stops. I never put the top down and I don't have side curtains, so the rear does catch some wind. My engine is all stock with 50 lbs compression, and I do run a thermostat. I always drive with the spark 3/4 down and the GAV closed and like to keep my speed 42 to 45 MPH.

For the water pump, be sure to only use lead packing rings and make sure you smear grease all over them when you install them. If that's what you have now, then unscrew the nut and pack a bit of grease in there and screw it back on. I quickly learned that the only way to stop a slow drip was to make sure grease was around the lead rings. I rebuilt my pump about 15 years ago and only checked the adjustment twice since then and have never leaked a drop of antifreeze.
 
I don't have exact figures. But I put $20 bucks a week in my pickup and usually end around 1/4 tank. My 1998 chevy s-10 get's atleast $20 bucks a week if not $40 to do the same amount of driving.
 
I get about 18 with my 29 Fordor, all stock. It DOES make a difference how you drive. When I am going down an open road I shut the GAV off. I usually drive about 45-48 and take it easy getting there. #1, I would say check your timing. #2, don't push it hard. #3, close down the GAV at least to 1/4 turn. #4, enjoy the ride, to heck with gas mileage!
 
You should do better than this in any Model A.

Check your initial timing. Having the spark lever all the way down but not having the initial timing correct will not get you the MPG you should get.

I agree with others that it is probably the carb. The float level might be high. The jets might be too rich. The GAV can't adjust that much. You do not need to run with the GAV 1/2 turn open. Close it after the engine warms up, then open 1/4 turn only if required. Many cars run OK with it closed.

You should also see about:
- dragging brakes
- slipping clutch
- clean spark plugs
- point gap correct and points clean
- good, open, free-flowing exhaust system

These will all kill MPG.
 
Hi Forker, Can you smell your exhaust? Does it stink? If you can smell it, you are running way too rich. Jet orifices are probably too big. Flow test the carb, or go to standard jet drillings if you are running too rich. 18 mpg is a great target for Model A's. Happy motoring!
 
Chris et al
I think I am running too rich and that is probably my major problem...according to my wife I can't smell anything, but she says she can smell it.
Thanks everyone
george
 
One other thing I thought of today... check the polarity of the coil.

If your car is wired like original, with positive ground, the wire the makes its way from the coil to the distributor points, through the ignition switch, should be connected to the post on the coil that has a little + symbol next to it.

If wired backwards, you get a weak spark. It will run, but not as well. Easy thing to check.

If car is now negative ground (common if it was converted to 12 volts) then that wire goes on the (-) post of the coil.
 
One thing not said and is the best way to tell how an engine is running is look at your spark plugs. A nice tan porcelain is ideal, black is too rich, white too lean.
One thing I learned is if you are running a paper air filter. It was too restricted and would be rich at highway speeds.
 
Forker said:
The tank was full, I topped it off.

I had tightened the nut, but just checked it again and there was room to tighten it some more and I did, later I'll drive and see if that helped.
Thanks
Click to expand...

If you have the non brass packing nut, it could be corroded and stripped threads
 
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