Fuel Consumption

[Dave Loving]

My 1915 CenterDoor seems to be starving for fuel. How much gasoline does a T consume in ounces per minute?
I want to compare that to the amount that is running into the Carb.

Dave

[TXGOAT2]

Fuel consumption is affected by a vast universe of variables in the car, the driver, the operating environment, the fuel, and the vehicle's condition. With the gas tank half full or more and the car on level ground, gasoline should flow freely from the fuel line at the carburetor connection. Modern type gas filters added to the fuel system often cause fuel delivery issues. It's best to stick with the original design and make sure it is operating as it should. Alway check the gas cap vent. A plugged or restricted vent will cause problems. Some types of float needle/seat assemblies do not work well on Model Ts. They are not designed for gravity flow fuel systems.

[got10carz]

If I remember correctly the 15 Center Door had a intake manifold that was especially long ( lower location of carb) to accommodate the fuel tank in a unusual location.
Maybe that is the issue.

[Humblej]

Dave, ounces per minute? Miles per gal is a more reasonable fuel rate, you could use an average of 17 miles per gal for a ballpark estimate. Figuring an average driving speed of 34 miles per hour will give 2 gallons per hour, converting to minutes, .033 gal per min, or 4.26 oz per min...if I did that right. Ouch, my head hurts.

[Oldav8tor]

More info such as model of carb would help. Also, is this a new problem or has it always existed? If the latter, I wonder if the carb float needs adjustment?

[RajoRacer]

Or procure one of Scott Conger's oversize inlet valve, if its a NH !

[Scott_Conger]

I want to compare that to the amount that is running into the Carb.

and how will you do that?

opening the drain plug on the carb will allow fuel to flow at a very fast rate...and the float will fall to the bottom, opening up the float valve to it's greatest opening. Your car while running, will never open the float valve all the way...if the float were to fall that far while running it would mean that the fuel is so low in the jet that the car will not run.

there is more to flowing fuel into the bowl than opening the proverbial spigot and measuring the flow while the car's in the garage.

You can ask the Forum what I am talking about and why, or you're welcome to contact me for more info - anything more here wouldn't be Kosher.

You may very well be right that it is starving for fuel, but you will do yourself a favor if you tell folks: what kind of carb, if it's rebuilt, if you have a fuel filter, and finally precisely what it is doing that leads you to the starvation conclusion,

[Dave Loving]

This car is new to me, I had the engine rebuilt, it was set up with a Model A Carb which I have changed to a Rebuilt NH.
When I first tried to start it with about 3/4 of an inch of gas in the tank it would not run. I added about 2", bringing the level in the tank to about 3", It would start, run for a bit and stop. I then brought the gas level up to 6", and it would start & run better, but still not long enough to drive, probably about a minute before it would die.
Hence my thought it was starving.
There in nothing in the line (filter, etc.) Standard Ford gas line.
It did originally have a fuel pump, which I have removed. The Model A Carb was several inches higher than the NH, so I figured the NH would be low enough that the pump would not be needed.

[TRDxB2]

This car is new to me, I had the engine rebuilt, it was set up with a Model A Carb which I have changed to a Rebuilt NH.
When I first tried to start it with about 3/4 of an inch of gas in the tank it would not run. I added about 2", bringing the level in the tank to about 3", It would start, run for a bit and stop. I then brought the gas level up to 6", and it would start & run better, but still not long enough to drive, probably about a minute before it would die.
Hence my thought it was starving.
There in nothing in the line (filter, etc.) Standard Ford gas line.
It did originally have a fuel pump, which I have removed. The Model A Carb was several inches higher than the NH, so I figured the NH would be low enough that the pump would not be needed.

You may be looking at the wrong end of the fuel system. The changes in fuel level in the tank may be pointing to some contaminated fuel in the tank as well as a clogged filter screen in the sediment bulb. The additional fuel, added weight, would increase the pressure in the fuel lines. Completely drain the tank and inspect the fuel.

Car dies out after 5 min https://www.mtfca.com/discus/messages/5 ... 1444047743

[Steve Jelf]

I don't know about inches, but "two gallons of gas is plenty but one is not enough".

[Allan]

Pat, you forgot to mention the variable volume of a gallon. We get better mileage with our imperial gallons.

Allan from down under.

[Luke]

Dave,

There are various ways to approach this, some of which have been described here already.

Were it me I probably wouldn't go to the trouble of mass measurement etc, instead I'd just put a raised clear plastic hose on the fuel line at the point where it enters the carburetor and then see where the level sits (this is in essence a hydraulic level). Initially this would tell you if you have sufficient height of fuel to work with.

If that was ok then I'd then drop the clear hose into a container and observe the fuel flow over a period of time - longer than the time it usually takes for the engine to stop. The fuel should continue to flow until the tank is empty, but if not then you may have a blocked filter or relief hole (the latter would lead to a vacuum forming and eventually nil or very little fuel flow - undoing the cap would show if this was the case).

Should both these tests be ok then it's unlikely the problem is due to fuel delivery, and you can begin to look elsewhere.

Luke.

[Dan Haynes]

If the car is a 1915, is the gas tank under the back seat? Ford found the slope from that location insufficient and changed to a longer intake manifold, unique to centerdoors, that held the carburetor a couple of inches lower.

[speedytinc]

If the car is a 1915, is the gas tank under the back seat? Ford found the slope from that location insufficient and changed to a longer intake manifold, unique to centerdoors, that held the carburetor a couple of inches lower.

The longer intake manifold was the key. I believe Ford ran a 5/16 fuel line also. Kim Dobbins would know.
I have never seen one of these super rare manifolds. It wouldnt be that difficult to extend a stock manifold.
There was a recent picture here of a farmer fix manifold made from pipe fittings. (cant find it)

To test the theory. Get or rig up another gas cap & slightly pressurize with a tire pump.

[John kuehn]

Sounds like a fuel starvation issue to me. A standard T tank to carburetor set up should work. It worked years and years for a T and still should.
Has to be a gas restriction from ,tank, sediment bulb or stopped or pinched gas line. Maybe the gas tank cap vent hole is stopped up. A T will and run OK with 1” gas in the tank but I would not drive too long or go on a hill. More gas the better.



Other than those things it’s in the carburetor somewhere.

[speedytinc]

Dave. The A carb with a "fuel pump" worked fine. Doesnt matter that the NH is lower than the A was. Fuel pump.
Does appear to be a lack of gravity fuel feed. The early coups with the gas tank in the trunk had the same problem & also had the longer intake manifold.

I had a model A carb on a 14. Ran ok with a full tank. Starved for fuel @ a half tank.
I resolved the issue by lowering the A carb 8". Runs great without a fuel pump now.

[speedytinc]

Did some digging & found this earlier post


Re: Mark Smith auction in Virginia
Post by KimDobbins » Thu Oct 20, 2022 5:36 pm

I owned a nice original real 1915 center door sedan. I sold it to the late Fred Lau of Portland. Mark Smith bought it a few years ago. It's a great car and I was hoping to see what it went for and who bought it. I guess it was sold prior to the auction. The gas tank was located under the rear seat, the intake manifold and carb air intake were about 2 inches lower the normal to aid in gas flow. It didn't seem to work very well. If that car even got a good look at a hill, it would starve for gas.

[tgiro]

Hey Dave, Is that Snap’s car? I always wondered who ended up with it.
Cheers,
Joe Amara

[Norman Kling]

One thing not mentioned is about the "rebuilt" NH carburetor. A few years ago one of the rebuilders used what was called a Gros valve on the carburetor intake. This is not a needle and seat but a ball valve which opens when the float drops and closes when the float goes up. The opening is insufficient to allow full flow of fuel. A standard needle and seat might cure your problem. Easy fix if that is your problem. If the car has been setting for a long time, sometimes the fuel in the fuel line sets like varnish. So unfasten both ends of the line and snake a wire through it to clean it out. Then connect the line at the sediment bulb and open the valve. The fuel should flow freely. Either of these things can cause a problem.
Norm

[Scott_Conger]

actually, commercial standard needle/seats have a through-hole no larger than a Grose Valve, and neither will perform correctly if you are pushing the car to its limits

There is a solution to that, though.

[RVA23T]

There is a solution to that, though.

And would that be one of Scott Conger's full flow needle and seat for the NH carburetor the likes of which is installed on my NH carb as it sits on the shelf in reserve???