I know this question will have a ton of variables and might not even be a good question to ask. When driving my car I get about 30-34 MPH (using a GPS) the spark lever is about half way to three quarters of the way down when it is pulled much further almost touching the belt, the throttle is about half way to three quarters of the way down. When I pull the throttle further I can hear the air in the carb (gets louder sucking sound) but does not change the speed. When the timing is moved between half and three quarters it done not seem to change. I have rebuilt the carburetor and have had the coils rebuilt commutator looks fine and it starts up easy. Does this sound normal? I know it is hard to say but I have only driven a model T once about 25-30 years ago and just looking for some information.
Both sound similar to the few T's I have started and driven. My daily driver, the War Wagon, has the timing rod 3/4 down towards advance and that seems to be the sweet spot. Eary on, it felt that all the way down was the sweet spot and I wonder if I could get it further down, it would run better. I read on this forum the prodedure for adjusting the rod over to the timing cover and set the 1 cyl to TDC and bent the rod slightly so it was in the proper position and made sure all the split pins or were tight so that I did not have any "slop" in the adjustment. It helped and I can over advance the timing now where before I could not.
Might want to look into that. Make sure no play in the connections from the steering wheel to the actual timing cover and carb so you do not "waste" any adjustment control.
But, overall, it sounds typical in my limited experience.
Not getting acceleration when you open the throttle more suggests to me that there's fuel starvation. Opening the throttle should feed more fuel and increase engine speed. From your description it sounds like opening the throttle isn't adding any more fuel. Do you happen to be using an inline fuel filter?
When you pull the throttle further down and hear the sucking sound try adjusting the mixture rod richer to see if you are starving for fuel as Steve is suggesting.
The Model T engine has pretty dismal volumetric efficiency at higher RPM. -I've read that this was an intentional measure with the intention of preventing the engine from producing more power than it's bottom end could withstand. -Part of the formula was to restrict the diameter of the intake manifold.
Mr. Ford was pretty obstinate about light weight and loathe to make anything stronger than it really needed to be and the car's unbalanced, 1-inch thick crankshaft was part of that master plan. -Restricting the amount of torque that went through it made for the expectation of a reasonably long part-life—though I doubt very much that Henry envisioned the darned thing lasting over a hundred years.
Now, imagine the deleterious effect of about a century of metal fatigue and maybe a couple of re-grinds along the way and you've got perhaps the cause of the founding of the infamous Two-Piece Crankshaft Club. -With that in mind, I wonder about the wisdom of installing high-compression heads, deep-breathing, aftermarket intake manifolds, more efficient carburetors, etc. -Silly me: Though I wouldn't have dared operate my engine at full-throttle for fear of breaking something, yet I installed all those speed parts on my engine. -I probably should have just left it exactly as Ford's design team so carefully worked out.
Henry, of course, was a very practical man with an instinctive sense of the relationship between power, weight, structure and gear ratios. -It also didn't hurt that he surrounded himself with individuals like Galamb, Sorensen, Huff, Wandersee and Wills who were gifted with the type of fine-tuning metallurgical and physics insight he himself didn't happen to possess. -In any case, the philosophy of his oversight and consistency of purpose steered the whole team in the same direction and the result was a car that was every single bit as strong and capable as it needed to be, but no iota more so than that. -To work that tight takes talent.
Working within the limitations of a low-revving engine, Ford picked a rear-end gear ratio such that on level ground, his little spitkit had just enough low-end grunt to go around a corner without the need for downshifting. -That, sure as hell, was intentional. -Yup, in his younger days, Henry really knew what he was doing.
Bob Coiro, That's a very nice summation. I can tell that The Nuns taught you English and grammer really well!
BTW, I really enjoyed the article on The Nuns and I've shared it with several friends.
everything you describe generally is normal, and I agree with Robert that you might want to fine tune the timing...you probably ought to feel a bit more "oomph" from timing rod at 3/4 way down, so check that. That will give you a few more MPH. At 38 MPH you are now 10 MPH over the useful range of the brakes, so be aware of that. Otherwise sounds fine.
When you have run out of torque, the sucking sound replaces increased power once you reach that point. Just throttle back. It won't change a thing.
causing harm or damage.
"divorce is assumed to have deleterious effects on children"
synonyms: harmful, damaging, detrimental, injurious;
I like it!
I didn't notice whether you said you were using the magneto or battery. I also have a 26 Roadster and ran it on 6 volt battery for quite a few years. On tours I was one of the slower cars especially going uphill. Later I repaired the magneto and began running the car on magneto. It became one of the faster cars on the tours. Another thing to note, your profile says you have a 26 Roadster. If you are running a vaporizer, it might be a bit slower than a car running with a carburetor. You have to suck the gas past a plate on the exhaust manifold. If you should have a vacuum leak at that plate it would get even less fuel.
Concerning the timer and fan belt. The belt can be adjusted by rotating the eccentric in either of two directions. When tightening the belt turn it in the direction which moves the belt farther away from the timer. This will allow you to advance the spark farther.
All the above information except for what Tim says applies.
I would agree with Steve.
I had to bend my spark lever linkage around pretty good to keep it out of the belt. My T likes lots of spark advancement. When well advance it pull very strongly at any speed, and when I advance the throttle it wants to get up and go, and it is all stock.
A few things that I might look at;
1) If you have an inline fuel filter do a test and remove it. They are not recommended due to fuel starvation.
2) Open your OEM fuel valve potato filter and clean the screen.
3) bend your spark linkage so it is out of the way of the belt.
4) Remove the potato valve assembly from the tank and see if you have any larger debris built up in the inlet. (I had corn Kernels blocking mine, when I started it back up, I had to clean it about 3 times).
5) May need to clean and adjust your carb.
Norm- taken right from Bob's post:
"Now, imagine the deleterious effect of about a century of metal fatigue and maybe a couple of re-grinds along the way and you've got perhaps the cause of the founding of the infamous Two-Piece Crankshaft Club."
Acceleration topping out at 34 mph is not normal. Advancing the throttle beyond 3/4 should make the car go faster. I'm not saying you should drive faster, but the car should be capable of it.
I do not have a fuel filter. I will check the screen and make sure a good gas flow is coming form the fuel shut off valve and flip the belt adjuster the other way and see if that give me any clearance and maybe a little more advance. I rebuilt the carburetor last fall when I bought the car but might just take it off and have a good look at it. I just wasn't sure what was normal.
This has to be the best post of 20017; Excellent summation of Henry Ford, the Ford Motor Co. and the Model T.
Hearing "sucking" in practical terms means you have run out of torque and the engine simply isn't going to go faster. You've opened up the butterfly beyond the point where the valves and piston will allow air to flow into the combustion chamber and you are actually raising the pressure through the venturi (less vacuum, which has the added drawback of lowering fuel flow). Going up a steep hill in high for instance, you will reach an equilibrium point where more throttle will create a "sucking" sound with no more speed. No amount of richness adjustment or any other salve is going to make that car go faster or be more powerful. I believe this is the case for you on level ground at 34 MPH.
So, why would that be? Let's look to your initial list of conditions:
If you have no response to advancing your timing beyond 1/2 to 3/4 of the way down, you're not running out of fuel, you're running out of advance. At 3/4 of the way down, running at 34 MPH, you should feel a small-to-medium jump in power (assuming you're running magneto) and if running on battery, you should have a steady increase in power as you advance through any part of the quadrant.
Based on your described symptoms, I would not initially look for a fuel problem, but would seek to ensure that timing was set correctly. If it all checks out precisely correctly, then you can look at fuel (or tight rear end, or dragging brake shoes, or overly tight transmission bands, or, or,or....)
I'm with Scott. Sounds more like the timing isn't advancing far enough. If it were fuel starvation, I would expect rough running, spitting, backfiring through the carb, etc. Running out of acceleration sounds more like the timing not advancing far enough to support it.