Retard / Advance?

[Mopar_man]

When timing my more modern cars (1960's Mopars) if you advance the distributer you get more power. Then depending on your octane level I would retard it so it didn't ping.

With the Model T and going up a hill (needing more power) you retard the ignition (timer). Why is is opposite? I know A lot of T owners leave their spark lever alone and don't have to adjust it.

[Norman Kling]

In your MOPAR car, the distributor has an automatic spark advance which works according to the speed of the distributor cam which is connected by gears to the camshaft. It also has a vacuum advance which automatically advances as the vacuum increases with closed throttle. So it does automatically what you do manually with the T. I tried the same thing you did many years ago but advanced too far and actually blew out the center electrode of one of my spark plugs. The "Ping" actually called pre-ignition which can try to force the engine to run backward. Not good for the crankshaft either. Our modern fuel, even the "Lower Octane" is higher than the High Octane in the days when Model T's were new cars.
Norm

[DanTreace]

It's normal to leave the spark advanced as far as possible while preventing spark knock from too early combustion.

Rarely does the spark need to be retarded running in high gear until the engine speed is hindered in deep sand or on steep hill, only then retard enough to match engine speed with road speed. Too much retard on steep hill will lose power in high, then of course by then your road speed is so low, you have to go to low pedal. Then advance spark of course as the engine rpms will quickly increase in low gear.

Moderate hill climbing with your 20hp Ford can be challenging, but lots of fun of you can get a running start when you see that hill coming up, neat to set the throttle advance at the right time to develop the necessary speed to crest that forbidding sight!


Best to go by the advice in your Ford Owner and Operator Instruction Book

[TXGOAT2]

When driving, you only need to retard the spark at very low engine speeds, and then only as much as needed. Correct spark timing, once the engine is started, is a matter of matching timing to the engine SPEED and LOAD. With poor quality fuel, the fuel's knock threshold has to be considered, as the Ford manual pointed out, but today's fuels all have such high octane equivalency that drivers can ignore that consideration.

It's best to approach a steep hill at a good rate of speed with full throttle and full spark advance.
Only if the hill is long enough and steep enough that your car speed drops to 10 or 12 MPH in high do you need to retard the timing, and then only partially. If you have to shift to low, the engine speed will go much higher, and you'd need to return to full spark advance.
It's always best to run on magneto. The magneto output varies with engine speed, and this can provide some limited automatic timing management. The coils will fire somewhat sooner at higher engine speeds, and somewhat later at low engine speeds.
If you are running on battery only, more attention would probably need to be paid to the spark advance, since coil timing, or time to fire, is fixed when running on battery.

[Moxie26]

The simple guideline to follow... Adjust the spark to the speed of the engine, adjust the throttle to the speed of the car.

[John Codman]

I start the engine and immediately advance the spark until it is running the smoothest, on Mag obviously, then when I actually start driving it I move the spark lever to the "sweet spot", then forgeddabout it.

[Craig Leach]

I ran my speedster with a stock engine, Marvel-Schebler up draft, large exhaust, Distributer, stock gear & no Aux. gearing for about 10 years. It
would run over 55mph on flat ground but was severally handy capped climbing steep hills & @ over 5,000' above sea level. Adjusting timing &
fuel with that setup is critical under heavy loads like S-6 in San Diego county were you have 7%+ grades & tight winding turns for miles. If you
have to go to low peal you will probably stay in low the rest of the way. Matching engine RPM with timing & fuel mixture with load with that
setup makes a huge difference in performance. However My firetruck weighing in @ 2,000#+ with a stock engine & manifolds L-4 Kingston
requires very little tinkering other than fuel for altitude & timing for load but the changes are noticeable. If the set it & leave it philosophy
held water I think Henry would have saved the money by taking the adjustments off & going with common cam lobe compression release that
was used on small engines & still is today. There are few things that annoy me when it comes to touring in a T it's fun laid back enjoyment but
having to fallow someone up a grade with black smoke pouring out the tail pipe & a chill up the spine rattle @ 12 mph. Then @ the next stop
in an attempt to help you ask if they are having trouble they say no it always runs like that. Thanks for letting me vent.
Craig.

[Oldav8tor]

Ford published this guide for spark adjustment. I find it works for the most part. Seems like you normally pull the spark down about as far as the throttle, making little adjustments as needed.

[John kuehn]

It all boils down to this.
Model T’s DONT have distributors or electronic ignition which regulates the operation of the engine. The DRIVER is the distributor that regulates the operation of the engine. This is meant to be satire but it is true!

[Mopar_man]

Thanks for all the input. I think i get it now. In high gear running up a hill with a full head of (steam?) you should have the spare advanced to match the engine. However if you need to go into low gear you need to retard it for the lower engine speed. I know each T is different and practice makes a better driver.

[Allan]

My model T roadster does have electronic ignition which controls the engine. It has an E timer. It starts with the spark retarded manually, but once advanced, the rest is automatic. I believe the I timer gives the same benefits. All my other T's have coils and timers which do require manual setting, but once rolling, I rarely have to adjust that setting.

Allan from down under.

[Craig Leach]

When in low gear the engine speed is faster than high gear @ the same speed. Think of timing & speed the same in relation to TDC slower the
engine the slower the timing is the fast the the engine the faster the timing occurs before TDC.
Craig.

[TXGOAT2]

Once the engine is started, engine speed and load dictate correct spark advance.

[JohnH]

My model T roadster does have electronic ignition which controls the engine. It has an E timer. It starts with the spark retarded manually, but once advanced, the rest is automatic. I believe the I timer gives the same benefits.

Allan, the I-Timer is manual timing only, but unlike the E-Timer it allows direct magneto operation. It's really a question of how your coils are set up, and if you want magneto operation, or automatic timing, as to which of the two best suits a particular car and its driver. The automatic timing of the E-Timer is quite impressive, noticeably extending the low end power.

[Allan]

Thank you John for the input on the I timer. I was aware that it allowed the car to run on magneto, and that the coils were fully functional for the purists, and it makes sens e then that the timing is in the hands of the driver.
I love my E timer!!! I carry a spare Anderson timer, but have never had occasion to use it.

Allan from down under.

[Daisy Mae]

Ignition advance as it relates to power/performance is not linear, it's variable. Timing is and always has been an issue relative to load.
Take your modern day dizzy vacuum function as a comparative example. At part throttle (high vacuum) the vacuum function adds in additional advance curve. But the more you open the throttle to WOT, or the more load the engine experiences, vacuum decreases to zero. The vacuum function on the dizzy is dialing back the advance curve in low vacuum conditions.
On a Model T, we just have to do that manually to seek the best settings for performance, but with some awareness/knowledge as to why. Back in the day they were taught that, we weren't being used to modern automatic functions.
One of my mottos when I was an engineer at AT&T, automation reduces skill sets and knowledge

[Steve Jelf]

Ford published this guide for spark adjustment.

The infamous spark/throttle chart is by Murray Fahnestock, not Ford (Page 432). Fahnestock is an excellent source of Model T information, until he isn't. I don't see any advice on when the chart should apply. In this case, I believe it may be suitable for driving on BAT, but some of the spark settings are irrelevant for driving on MAG. How many useful magneto settings are available on MAG? Three? Four? How many does the chart show? Six? Seven? When you're driving on MAG, I suspect your ears are a better guide than the chart is.

If I'm wrong on this (that did happen once) maybe somebody can explain why.

[Oldav8tor]

I stand corrected. I just looked at a 1917 owners manual and there is no chart. There is very little said except to advance the spark notch by notch until the engine seems to reach maximum speed but not so far as it starts to "knock." Not all that helpful.....

[TXGOAT2]

Again, it's engine speed and load that determines the right spark setting at any given time. With today's gasoline, you won't likely hear any knock or ping, even with the spark over-advanced for the situation. Timing that is advanced too far is hard on the engine and reduces power. Timing that is late reduces power and increases heat. Ford put the spark control at the driver's fingertips for a reason. Under most riving conditions, it needs adjustment to meet changing conditions of speed and load, much as the throttle does. With a little practice and understanding of what the engine needs, adjusting the spark lever can be as automatic for the driver as adjusting the throttle lever is.

[TXGOAT2]

When running on MAG, the timing does not change in a linear fashion with a given movement of the lever. There are usually 3 positions or ranges of the lever's travel that have a significant effect on the timing, and they are typically about 1/4 of the way down, about halfway down, and all the way down. Some variation within these ranges probably occurs, since the coil cannot fire until the timer contacts close. When running on battery, the timing changes in sync with the movement of the lever. Putting a timing light on your particular car might reveal a more exact picture of what is going on, but what matters is keeping the timing as close to what the engine needs at the moment. The conveniently located fingertip control makes this fairly easy.

[Mopar_man]

Wow! Thanks for all the input. This is great and what I love about this forum.

[Susanne]

There is also the phenomenon of the magneto-coil synchronicity (ergo the "auto-synchronous Ignition System" noted on your coilbox switch) that when the car is running on mag, your spark lever is actually selecting between one of 4 possible spark impulses, rather than being a smooth, linear advance curve as on a distributor (or while on BAT)... I actually played with this on my car, and if you listen carefully, as your spark goes from one field coil impule to the next you can hear the change.

Dead simple and almost foolproof. It's also why when starting on mag, I pulled the spark lever down about 4 notches because it put the spark impulse just a hair on the retard side... and she started oh so sweetly, no need to trip over the front fender and wheel racing to get the spark lever pulled down before it died. Trying the same on bat, I forgot and strained the muscles in my arm when it "pullrd back" from such abuse. The only time I have the lever all the way up is when I'm shutting down.

[Art M]

Susanne,
The topic of magneto output is interesting. I am going to try to detect the magneto transition while moving the timing lever.

I am wondering why you fully retard the spark when shutting off the engine.

I have noticed that my car starts better when the spark lever advanced by a few notches from the full retard position. The timer linkage is adjusted so that full ¹retard is 15 degrees. The car starts very easy on mag when cranking by hard or by the electrical starter.

The 15 degree retard recommendation was most likely based on playing it safe to stay away from possible kick back due to misadjustments and linkage wear.

Art Mirtes

[Steve Jelf]

I have noticed that my car starts better when the spark lever advanced by a few notches from the full retard position.

Yes, when you're starting on MAG. When starting on BAT, I believe it's best to have the lever all the way up. I expect this applies before 1919 and later cars too.

[Norman Kling]

There is a reason for the difference between the battery and mag starting positions of the timer. When on Battery, the coil begins to buzz as soon as the rotor comes in contact with the segment on the timer cap. but on Magneto, the sine wave builds up and it reaches the point of spark as the rotor advances later on the cap. You want the spark to come at the right point so the spark plugs fire at the right time.
Norm

[Susanne]

Susanne,
The topic of magneto output is interesting. I am going to try to detect the magneto transition while moving the timing lever.

I am wondering why you fully retard the spark when shutting off the engine.

Drops the engine speed, if you're coming back to start on Bat better odds of a free start. It also means you don't forget to put the spark lever up when you go to start it if it's already all the way up - so if you're in a hurry, your spark lever is in a safer place.

Again, especially if you're starting on Bat. I also remember starting someone's car that had never (as in NEVER) bit anyone until I pulled it through. Having been though it before I knew to expect the unexpected, and how to safely let go of the crank to where it just pulled my arm, not broke it.

[John Codman]

I rarely differ with Steve Jelf, but my T starts better on BAT with the spark advanced about three notches (I have never attempted to start it on MAG). There was a thread here perhaps a year or so ago - it may have been Ron Patterson - who pointed out that with the spark lever all the way up, the spark is extremely retarded, and that the piston that's getting spark is well down in the cylinder. If you "advance" the spark a notch or three, the piston is still past top dead center, and the compression pressure will be higher. You will get a bigger bang in the cylinder. Sometimes my T will not start at all fully retarded.

[Charlie B in N.J.]

It’s pretty simple. Low revs retard position high revs advance to where it runs best. Your ears are your friend. As to Steve and Art they’re all different. Wear settings whatever as you need to get to know yours. On one of Steve’s videos he started the car and immediately yanked the lever 3/4’ of the way down. That’s a bit nope for me.

[TXGOAT2]

Yanking the lever down would be appropriate if starting on battery.

[Steve Jelf]

Yanking the lever down [after the engine starts] would be appropriate if starting on battery.

[Harvey Bergstrom]

The retard/advance on the Model T is something that sometimes takes a little practice to get to that sweet spot, especially at high speed. I had the misfortune of experiencing a back fire and blowing apart the muffler. Too much advance is not a good thing as I found out the hard way. Don’t assume just because you may be driving 40 mph that you need the lever “all” the way down. Now I set mine approx 2/3 of the way down and the engine purrs as it should and have great power too! If your commutator rod is set correctly, you will get all the spark advance you need without bottoming out the lever. Anyone correct me if I am wrong.

[TXGOAT2]

At best, the lever position is only a general guide. Wear of parts and adjustments affect the relationship between the timer and the lever, along with a great many other variables. I use the spark lever as needed to get the best performance and to avoid damaging myself or the starter when starting the engine. Once the engine is running, engine speed and load determines the best spark setting. Since both engine speed and load are almost constantly changing when the car is being driven, the ideal spark setting is also almost constantly changing as well. Generally speaking, when the car is moving slowly in High, such as right after making the shift from Low to High, the spark needs to be retarded. As the car gains speed, the spark needs to be advanced. This can be done with a flick of one finger. The cars BECM collects inputs from the behavior of the car and the sound and vibration the engine makes to program the timing to suit the operating conditions of the moment.

[Charlie B in N.J.]

Sorry but I disagree with advancing the spark when just starting /idling. Incorrect AND the diagram shows nothing like that. You advance the spark when you increase the revs not at idle.

[Moxie26]

You are also correct. Charlie...... This spark is advanced with the speed of the engine, and the throttle is advanced with the speed of the car. When shifting into high, the spark must be retarded by half distance to easily pick up the shift into direct..,....,.. All the Artificial Intelligence postings must be ignored , and accepted as false, and used by practical application.

[Charlie B in N.J.]

As I stated earlier, and I don’t know where I learned about it, but I’ve used the spark retard shift method for a long time. It’s the best system I’ve found.