MTFCA Forum

What would cause a T to not go faster than 20 miles an hour in high gear?

Let's see..... raccoons in the rear compartment?

Maybe throttle rod to carb isn’t proper bend to open the butterfly fully? Maybe emergency brakes or trans linings are dragging?

There are too many things to list that could cause a Model T to top out at 20. It might be good to have and experienced Model T person look at it. My express wagon would only go over 30 downhill with a tailwind. I thought it was just aerodynamics, but one day I just happened to notice that the choke rod was only allowing the choke to come about half way open. I’ve corrected that, but I’m in the middle of some other engine work, so I haven’t run it yet but expecting great things…

Like the man said, too many things. What Model T, stock, altered... What is the gear ratio? Top speed on a basic TT, I believe, is 20mph.
This Google search might help find an answer
https://www.google.com/search?q=top+spe ... CA0&uact=5

This question would bring up other questions.
1. Are you going uphill, downhill, level ground, head wind, tail wind?
2. How many passengers or other weight are you carrying?
3. Are your brakes all the way off?
4. Is the engine running smoothly, or misfiring?
5. Did you get a running start uphill, or are you trying to start out on a hill"
6. What is your gear ratio?
7. Do you have any after market "speed" equipment on the car? Some "improvement equipment will give you more torque at low speeds and others will give you more speed at the high end. Some come in a complete package and will make the car run worse if only a part of the package is used.
Other questions
1. Is the engine running smoothly but only 20, or does it run as though you are running out of gas?
2. Are your tires running low?
3. What body type do you have? Some are heavier than others, and some have more wind resistance.
4. What is the position of the spark lever?
I could go on and on about this, but do need more details than given. I have a touring, and when I am by myself I can pull a certain hill in high hear, but with 4 people in it, I need to shift down. I have another with high gearing and it will go fast on level but doesn't like hills very well.
So give some more details and comparison with other cars in same circumstances.
Norm

FWIW: A friend of mine had that issue with a new bought Model T.
4 rebuild coils and proper adjustment of the timer solved that problem.

But I concure with what the other says: It can be a lot of things.

This sounds like my car when it acted up today. Turned out to be a coil. Went from running great for 20 miles to limping for 15 miles to get home home. Changed the coil and the engine returned to running well.
Maybe that's all that is wrong with your car.
Art Mirtes

26 coupe. 2 people. Flat ground. Rebuilt coils by reputable rebuilder. New gapped plugs. Doesn’t appear to have band drag.

If the engine starts well, idles smoothly, and runs smoothly, I'd look for problems with the throttle linkage, timer linkage, and choke. Another possibility is a severely restricted exhaust due to mud daubers, small children, or mice/rats. If the car has an air filter, remove it and examine it. Mud daubers have been known to build nests in carburetors, too. Valve adjustment is another possibility. Tight exhaust valves could limit engine power as the engine warms up.

Will_Vanderburg wrote: ↑

Mon Nov 01, 2021 1:53 am

26 coupe. 2 people. Flat ground. Rebuilt coils by reputable rebuilder. New gapped plugs. Doesn’t appear to have band drag.

Need to ask if this was a problem prior to the coil rebuild and new plugs or since that was done.
If its not running as well "after" then need to recheck whatever other adjustments were made:
-Are the throttle connections opening the carburetor all the way?
-Check timing, spark rod movement

TRDxB2 wrote: ↑

Mon Nov 01, 2021 10:05 am

Will_Vanderburg wrote: ↑

Mon Nov 01, 2021 1:53 am

26 coupe. 2 people. Flat ground. Rebuilt coils by reputable rebuilder. New gapped plugs. Doesn’t appear to have band drag.

Need to ask if this was a problem prior to the coil rebuild and new plugs or since that was done.
If its not running as well "after" then need to recheck whatever other adjustments were made:
-Are the throttle connections opening the carburetor all the way?
-Check timing, spark rod movement

The coil rebuild had no effect on the speediness of the car.

When I go back to their house after the new year, I’ll check some of the other stuff.

Some parts work good together as a package, but not very well if used alone. I was given a "high volume" intake manifold as a door prize at a meeting. Everything else on my T is stock including a NH carburetor. The car ran good at high speeds on level ground, but very sluggish starting out or pulling a hill. It actually ran better with the throttle partially closed. Later I installed a standard intake manifold and the car runs as it should. It is kind of like trying to blow out a candle with the mouth wide open. The candle can be blown out with the lips almost closed. There must be a rush of air past the fuel input jet in the carburetor to suck the fuel into the engine. With the throttle open and a larger manifold, the fuel does not rush into the cylindars . If it had an enlarged exhaust on it and a high compression head, and maybe a different carburetor, it would have ran great.
Anyway, it could be any of the many things I posted above causing your problem. I would suggest you take along someone with you to look at the car to help you find out the cause of the problem.

Norman Kling wrote: ↑

Mon Nov 01, 2021 11:34 am

Some parts work good together as a package, but not very well if used alone. I was given a "high volume" intake manifold as a door prize at a meeting. Everything else on my T is stock including a NH carburetor. The car ran good at high speeds on level ground, but very sluggish starting out or pulling a hill. It actually ran better with the throttle partially closed. Later I installed a standard intake manifold and the car runs as it should. It is kind of like trying to blow out a candle with the mouth wide open. The candle can be blown out with the lips almost closed. There must be a rush of air past the fuel input jet in the carburetor to suck the fuel into the engine. With the throttle open and a larger manifold, the fuel does not rush into the cylindars . If it had an enlarged exhaust on it and a high compression head, and maybe a different carburetor, it would have ran great.
Anyway, it could be any of the many things I posted above causing your problem. I would suggest you take along someone with you to look at the car to help you find out the cause of the problem.

Norman, I appreciate the advice, but I don't need anybody to go with me and hold my hand, because with my own car over the last 25 years, except for the MAJOR mechanical crap, I can usually figure it out. This person's car runs and drives, as I am the one who got it to run from its past sleep. I only have a limited number of hours to see the car when I go to their house (Which is ELEVEN hours from me), it is not feasible to have another person tag along.

Next time I go down, I'm going to remove the carburetor and make sure it's up to snuff, and will continue on from there.

Again...Thank you and everyone else for the suggestions given.

Had timer linkage disconnect once. Acted like this. Maybe a simple fuel line obstruction.
You can bet it will be something stupid simple when you get your hands on it.

speedytinc wrote: ↑

Mon Nov 01, 2021 12:20 pm

Had timer linkage disconnect once. Acted like this. Maybe a simple fuel line obstruction.
You can bet it will be something stupid simple when you get your hands on it.

Most likely. I’m inclined to agree.