I have had my 1926 Model T Coupe for 43 years and have driven her many miles, always exclusively driving her with the spark fully advanced. That is where I get the best performance whether I am cruising slow through the neighborhood or going 30 on the straightaway. If I retard the spark, even a little, the engine does not run as efficiently and power seems to falter, so once I am underway, I have just found it easier to advance the spark all the way and leave it. Does anyone see a problem with this. I should point out that the engine runs very smoothly and quietly in high even if the gas lever is pushed almost all the way up. Jim Patrick
You are a lucky man. I also have a 26 Coupe. You live a sea level and have no hills to speak of. I, on the other hand live in the mile high city (actually mile high + about 250 feet) and have some mild hills known as the Rocky Mountains to deal with. You can get away without adjusting spark. I can't. I am about to meet Mike Walker and some other T friends in Arkansas for a week of T driving. I am always amazed how much more power my T has in Arkansas!
Gee Jim, I'm a bit of a novice but I am fairly sure fully advanced is the way to go, as slightly more modern distributers advance on weights by centrifugal force. The weights move back against a spring as revolutions drop and hence retard the spark a little. However at very slow revolutions the T engine should have a bit more power slightly retarded. cheers
Jim, that's basically the way I drive. Put it in the sweet spot and leave it there.
Jim, My father and I always advanced the spark on my grandfather's 27 coupe, just as soon as it fired to life. Running it, even at idle, increased the idle RPM's with the spark, advanced. Of course if we wanted to 'show off' to someone how slow it could idle, then we'd retard the spark as much as possible.
When running on magneto you really don't have to adjust the spark too much but, running with the spark fully advanced at any engine speed is not right. After starting the engine gradually advance the spark until the engine picks up speed and runs smoothly. As you pick up speed advance the spark until the engine runs best. If the engine does not respond well when the throttle is opened or feels "lopey" try a little more advance. When the engine slows when pulling a hill or when running at slower speeds slowly retard the timing until the engine feels most powerful. If it feels sluggish you have gone too far. For the most part I have found that once you get going set the timing and leave it alone. When driving at higher speeds it will want a little more advance and when pulling steep hills it will want a little less. For max speed pull the timing all the way down. Every T is a little different so set your spark where your T runs best.
I am looking forward to driving my T in Arkansas since I can join you guys that set the spark to the sweet spot and forget it.
Have you ever set the timing properly? It sounds like it is probably retarded too far.
Check the timing by moving the engine to TDC on #1. Then, using a drinking straw on top of the #1 piston with the plug removed be sure that the spark occurs just past TDC. You should feel the drinking straw move down as you pull up on the crank. The coil will buzz just slightly past TDC if the timing is set properly.
I suspect the coil will buzz far after TDC. You will have to bend the timing rod slightly to achieve proper adjustment.
This thread may be of interest from the last time you asked this question:
And also posted in that thread is this image:
Even though your engine runs fine and a single spark advance setting I would bet that at least some small improvements in performance may be realized with some spark advance adjustment under some conditions.
If there was no improvement is performance designers would have never added centrifugal advances or vacuum advances or now computer controlled advances,
This is from the Ford manual:
Good operators drive with the spark lever advanced just as far as the engine will permit. However, advancing the spark too far will cause a dull knock in the motor, due to the fact that the explosion occurs too early. The spark should only be retarded when the engine slows down on a heavy road or steep grade, but care should be exercised not to retard the spark too far as this will result in late ignition, which causes loss of power and overheating of the motor and may also result in warped, burned or cracked valves. Learn to operate the spark as the occasion demands. The greatest economy in gasoline consumption is obtained by driving with the spark advanced sufficiently to obtain the maximum speed.
RE: centrifugal advance I have often wondered what is going on. On Atwater Kent distributors you can get by with one spring, yet the dist's are set up for manual advance.
I think really all it does is advance the timing a few degrees on start up, like running around the car and pulling the spark lever down.
The Bosch 009 dist seems to be the dist of choice. Those dist are designed for engines that turn 6K RPM or better. Now they all could be set up for an engine turning 1.8K but really why do it with a spark advance lever? Just my take and a theory. Again if they were set up for full advance at lower RPM the spark lever should become redundant.
When we compare fully advanced with fully advanced, should we not consider the bend/s in the small rod to the commutator as well??
My 13's both runabout and touring, both run at the mid way to 3/4position just fine, we have hills and flats, the worst will see me move either car a couple of notches only to retard on a good hill.
My wifes 26 Tudor, is about the same.
I time all my cars the same way and try to keep the timer rods the same as well in order to clear all the potential obstacles they can rub against. For some reason my '14 and earlier cars run best with the lever about 1/2 to 2/3 of the way down. The later cars seem to run best with the lever all the way down. I have never been able to figure out why this is but I have noticed a similar situation when working on other people's cars as well.
I can tell you that I operate my T the same as you, and have also found that operating the car with the spark in any other position than fully advanced reduces power and makes it run rough.
I cannot debate the "theory" of optimum spark timing as it relates to different driving conditions. But in practice, my T runs the best with the spark fully advanced, all the time. And if I may add, it runs damn good that way.
See the pictures from Jim's post above? That is pretty good advice.
Retarding the spark halfway sometimes results in better pulling power on hills. Again, this is dependent on the timing being set properly in the first place. If you don't find any advantage ever from running the spark at any other setting than full advance you have the initial timing retarded. The timer rod needs to be bent to properly index the timer. You will be pleasantly surprised how much better your car can run with the timing set properly.
Also, when descending steep hills or slowing down for stop signs, you will find that the car maintains a slower speed and decelerates much more with the spark fully retarded.
We are talking about apples and oranges here. The Model T spark lever is bent differently on each Model T so no two run alike. Fully advance on one car is half way on the next one. The only way to find out where you are with the advance-retard system and also if you are on battery or magneto.
To find out where you are on the scale simply pull the fan belt off and use a timing light while looking at the pin in the lower pulley and watch the advance and retard move as you run the engine and swing the lever up and down advancing and retarding as you go.
You can get a paper scale and wrap it around the pulley in order to get accurate readings.
Jim, you only posted once in this string, and there are a few things you did not address. Are you using coils or distributor? Or do you have some other after market type ignition? If you are running on coils do you use magneto or battery. What type head is on your engine?
Any of the modifications listed above will affect the performance and the need to advance or retard the timing. Also the initial setting with the spark lever all the way up will affect things.
Let us know all the facts about your ignition system, then we can do a better job of assessing things.
I don't drive like most of y'all. I retard the spark before locking the low band so it can be done at a low rpm without stalling the motor. Then I advance it while winding out in low. While shifting high I retard it again and never fully advance until I reach about 25mph. My cone clutch car cannot be shifted with out serious crunching if u don't retard the timing. And that includes double clutching and waiting for the motor to slow.
What kind of cone clutch car?????
Most of my Ts have run about like Jim P's car (fully advance, and leave it). I do retard slightly when pulling a long hill. And if running on factory magneto, again remember, the actual timing is set by the magneto, not the timer (except for retarded to a previous pulse like for starting).
How are you doing? Recovered fully from the wreck last year?
Drive carefully, and enjoy,W2
Wayne, I withheld the car's marque for a reason. It's a Chebby
490 1922 touring. ( GM model T) last year of the 490, contrary to popular belief.
When running on magneto you are dealing with 16 pulse's, even if the roller or brush is in the middle of the timer contact segment, it will fire when there is a pulse from the magneto. Unlike a battery that will fire as long as the roller/brush is in contact with the segment in the timer.
If you are trying to say the position of the timer lever does not change the timing when running on MAG then that is a false statement. There are at least three separate, distinctly different levels of advance available if the timer linkage is working and adjusted properly when operating on MAG.
My engine has a high-compression head, which, according to articles I've read in various publications, changes everything. The retarded section of the quadrant is useless except for starting the engine and coasting around a corner in high gear. There's a short space between the retarded and advanced ends of the arc which causes pronounced roughness. Then, there's a 3/4" "sweet-spot" in the middle of the advanced half of the quadrant. Fully advanced is too advanced to be useful and all it does is make the engine knock. In my case, there is no feeling of gentle graduation between settings, but abrupt shift-points.
But only the one occurring at the right place and time fires the charge. What I was trying to say is, you can't think of the magneto in the same context as a battery.
Norman, I run on coils adjusted by Ron Patterson and a magneto rebuilt by Wally of Total Recoil. I choke the the car and start her on BATT with the floor button starter, with the spark fully retarded and the throttle lever advanced, then advance the spark and switch to MAG as soon as she starts. My spark lever linkage is the original rod, still bent exactly the way it was when I bought the car in 1970, so I have never felt the need to adjust it and don't intend to, as it runs so well the way it is.
Yes, Florida is very flat and there are no hills to speak of that would require retarding the spark for extra power.
Thank you for asking Wayne. My right leg (femur) has fully recovered from being badly broken back in February 2012 and equipped with a long rod through the center of it, is now my good leg, for my left leg has now developed problems from having had to do the work of both legs for 9 months until my right leg was healed enough to walk without a cane. Coincidentally, I will be going in tomorrow for an MRI to see what the problem is and why it is so painful to walk on my left leg, which in January, formed a Baker's cyst on the backside of the leg joint and seems to be impinging on the nerve and the joint, which keeps me from being able to straighten the leg normally. The orthopedic surgeon seems to think I have a torn meniscus (whatever that is) which caused the baker's cyst to form and he wants to find the root cause so the Baker's cyst won't keep coming back. Thanks everyone for your help and opinions. Jim Patrick
When running with coils on magneto, you will notice 3 what I call "nodes". Node 1 is with the spark fully retarded as used for starting. Node 2 will be approx 10:00 on the quadrant and node 3 will be approx 8:00 on the quadrant. If you start out with the lever all the way up, and start pulling it down slowly, you will notice little if no change until you get down about 5 or 6 notches, then it will suddenly speed up. Pull it down a few more notches and no noticeable difference until you get it down past about the 9:00 position, when suddenly it will speed up again. It will run best in the middle of the "node". On relatively flat land you can just pull it down into node 3 and leave it there. If you want a little more slow speed power such as quick acceleration, or pulling a hill the middle of node 2 will be better.
If you just leave it in the middle of the node, the spark will automatically advance or retard just a little with the speed of the engine. That is caused by the difference in voltage and speed of the sine wave generated by the magneto. It is interesting information, but not essential to the operation of the T. Just remember to put it up for starting and down for driving.
I run on the magneto and have Patterson coils.
I retard for starting and advance it almost all the way after that. Someday I'll figure out what advanced and retarded is.
When I get to a hill or incline where the car slows a bit I retard it slightly.
Thanks for the explanation. At what you call "Node 2", my engine sounds like it's laboring, like its under a load. Is this normal?
Perhaps that is the reason for my hesitation for retarding the spark on hills. At "Node 3", the RPMs are high and smooth. Retarding it to "Node 2" where it sounds like it's labored, while you are already loading it going up a hill, seems counterintuitive.
Retarding the spark lever all the way when going DOWN a hill significantly improves engine braking. So you don't have to keep working the brake pedal as much.
Dan, that would be normal when going on level or going fast. However, the second node works very well when pulling a grade or right after shifting from low to high. It will just keep chugging along. But if it still slows down in node 2, it's time to shift down and then advance to node 3 again when in the lower gear. The different positions are directly related to engine speed rather than to vehicle speed.
To me, the chart that Jim Thode posted pretty well explains the proper use of the spark advance lever. It might be interesting to consider how the automotive engineers designed the ignition advance systems that were prevalent from the Model T/Model A era all through the '40's, '50's, '60's and into the '70's:
The typical ignition system during that era worked basically as follows:
Ignition timing of a typical engine was retarded before the engine was started; as soon as the engine started, a vacuum diaphragm immediately advanced the ignition timing a small amount due to engine vacuum as soon as the engine started. (this might compare to advancing a "T" spark lever approximately halfway up from full retard) As rpm's increased, centrifugal weights in the distributor gradually advanced the ignition timing accordingly and reached maximum advance at a fairly high rpm as designed by the engineers. (this might compare to slowly advancing the spark lever in a "T" further toward full advance as speed/rpm's increase.)
Driving a Model "T", trying to sort of "mimic" the action of the spark advance as described above might serve as a rough guide as to how to use the spark advance lever in "ol' Lizzy".
Hope this helps,......harold
Seems the spark advance is a mystery to a lot of folks. Some even seem to be scared of it. No reason to be. While driving, play with the dang thing! See where it runs best under different conditions. You aren't going to hurt anything. Just don't leave it advanced while trying to start, and don't try to go down the road at highway speed with it fully retarded. (Don't worry, you won't get to highway speed with it fully retarded.) I will agree with Royce. If you can't tell that it does anything, then your initial adjustment is out of whack.
I won't claim to be an expert, but let me try to explain what the spark advance does and why it exists in the first place. When your spark plug ignites the fuel mixture in the cylinder, it doesn't happen instantaneously. It takes the spark a certain amount of time to ignite the mixture. It takes the first bit of burning mixture a certain amount of time to ignite the rest of the mixture. It takes the burning mixture a certain amount of time to build enough pressure in the cylinder to push your piston down. Granted, it ain't a lot of time, but it does take time. And for the sake of this explanation, lets say it takes the same amount of time no matter how fast your engine is running. So, let's say you fire the plug at top dead center while starting the car. At this slow speed, the burning mixture will build pressure while the piston is still pretty close to the top of it's stroke and can exert pressure on the piston for most of it's full stroke. But at 1800 rpm, the piston is moving much faster. Remember, we are assuming the time for the burning mixture to build pressure is constant. So, for that same amount of time it takes for the pressure to build after the plug is fired, our piston may have moved 1/2 way down the cylinder before the pressure builds enough on top of it to do us any good. You just wasted half your stroke. The faster the engine is turning, the worse this scenario gets. The solution? Fire the plug earlier! Fire it before the piston gets to top dead center. Yeah, it sounds like you will trying to push it down before it comes all the way up (and that is exactly what happens when you try to crank without retarding the spark), but remember, it takes time for the pressure to build. During that time, the piston continues to travel upward, and if everything is set right, the pressure begins to push down on the piston just as it passes top dead center and utilizes the the whole stroke to make power.
So you see, the amount of spark needed is dependent on engine rpm. The slower the engine, the less advance you need. The faster the engine, the more advance you need. It's all about where the piston is going to be when the burning mixture begins to produce pressure in the cylinder.