I feel a T only runs good as it can Idle . Started up the T tonight cause it's Music, it has never ran this good, ( hope it lasts for the tour) . I can lower that engine down to a low more likely 400 rpm , I'm going to place an analog meter to se how far I can go with backing off the retard what's ever it takes as far as it will go Low till Dead ( stall is not the proper word ) Anyone know proper low go on a Flat head. Best idle in the world? I am running 89 octane no marvel mystery oil , never heats up do to new recored Radiator . Finally I think I have this dialed in with out a dyno all by ear fine tuned T
If it starts on the first pull, that's good enough for me.
The late Bob Schultz in North Branch, Minnesota had a 1919 touring that he would display at car shows and "free start" all day long.
He had adjusted timer so he could overly retard the spark and he would idle the motor so slow you could literally count the "chugs."
Idling the engine very slow is OK but don't try to drive super slow since you need to keep the RPM's up to prevent lugging the crankshaft. I know a fellow who liked to putt around the parking lot in high gear with his car very silent since he was running it really slow. To date he has broken 4 crankshafts and he does not drive his T all that much.
In answer to your question, it will go until something goes wrong, which could be any miriad of things in the fuel system, electrical system, cooling system or mechanical system. In the case of a new rebuild, where it's reliability is dependent upon the skill and attention to detail of the mechanic that did the the work, it could go for years or, in the case of an older restoration where the parts are getting older, it could die on you in the next minute for something as simple as a disconnected wire or something as serious as a thrown magnet. I overhauled the engine in my '26 coupe in 2010 and it has run beautifully ever since, but this is an 88 year old car so I am always expecting something to go wrong and will not be surprised, or particularly upset when it does as it comes with the hobby. Jim Patrick
Sorry. I misread your question as "How long will a T go" Sorry. If I could edit, I would remove my post...
If you meant how slow will a T go, John Regan said it best, but going too slow is not wise. I can get mine going so slow as to be able to count the chugs, which is impressive, but it scares H--- out of me everytime I do it. Jim Patrick
With an E-Timer and richened up Holley "G", I got my 1912 stock engine down so slow that you could count the cylinders as they fired: 1-2-4-3 ~ 1-2-4-3. I would say it was turning about 180 RPM at that rate. Many single cylinder cars with big flywheels will do much slower. With a Model-T, a nice slow idle will prove that all things are working properly in each cylinder (valves/compression)as well as ignition and gas mixture (carburetor). It should then run equally well at normal speeds.
Will a T engine lubricate properly at very low RPM?
I set my T's to idle at a "comfortable speed", which is probably faster than many if not most.
Both of mine will idle at well below 300 rpm when warmed up. Certainly low enough to count. I count them for 15 seconds on my watch and multiply by 8. I do this pretty often just for self satisfaction.
Hal, Let's see, a four cylinder four stroke ignites two times per engine revolution, so if you can count all the ignitions for 15 seconds, you would only need to multiply with two to get the number of revolutions per minute, or am I mixing up my thinking here ?
Sorry. I guess what I am doing is counting every fourth ignition. It kinda has a rhythm to it and each coil has a distinct sound. I count the sound of one particular coil for 15 seconds then multiply by 8.