Fuel Consumption !

[owner53]

My Cadillac Convertible 1953 has an extremely high fuel consumption; 8,0 miles per gallon !!!

I have checked compression, vacuum, carburetor and levels of the

floats, ignition and the fuel pump. All of it seems ok, and the car is

running perfectly. The spark plugs are also checked with right

colour.

The only trouble is the high fuel consumption !!! Where does the

fuel go !!!

The cylinder heads are renovated.The pistons and skirts are also changed.

Does somebody have an idea of where to find the failure ???

No hole in the gas tank......

Best Regards,

Peter

[Guest imported_Speedster]

If you are sure you don't have any leaks at engine, lines or tank, then the gas has to be going out the exhaust pipe. It may be a weak spark getting to some or all cylinders, caused by low voltage into or out of Ignition-coil or sparkplug gap set too wide. Or it may be engine timing adjusted incorrectly.

[Pontiac59]

Given what these weigh, unless you previously got much better milage 8 isn't too far out of line for city travel in this car. However I'd think more like 14-15 about normal. But I'd recheck my figures first - note the location of the gas needle with it at 1/2 tank or below (1/4 or 3/8 would be ideal), add 3-5 gallons of gas, note again needle position and odometer, and drive until the needle's at the low mark again. Maybe do it a couple times, and have the car level when you observe the needle. Idea is to try to eliminate some of the variables, and check when the tank float is actually floating and not submerged (it can only go so high in there). Every GM car I've been in the guage runs slowly until they get below 1/4 tank or so, then they drop like a stone.

If gas is going out your tailpipe, the car might have a tendency to backfire when it's hot as the gas burns in the exhaust instead of in the engine.

What shape is your transmission in? It slipping at all? Power steering, air conditioning on it? Brakes and parking brake working correctly, wheel bearings in good shape? making sure nothing is creating a drag. Gasoline of good quality and correct octane? Sometimes this will make a difference if your car isn't quite tuned properly.