Page 1 of 1

13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Sun Dec 27, 2020 5:44 pm
by Darin Hull
You start one project then find two more which need to be done. This is a case of I don’t know what I don’t know.

The advance lever, though the commuter rod, has to send the timer through a certain range of motion in order to generate a spark in the cylinder at a certain amount of degrees before or after TDC. I would believe this range begins with the advance lever fully retarded which should translate to 15 degrees after TDC. I have set that end of the range by following guidelines on this forum.

The other end of the range, at which the advanced lever is set to its most advanced setting on the quadrant should translate to a certain amount of degrees before top dead center which I don’t know. Figured it was equal to or great than 45 degrees.

So that’s question 1... how many degrees before TDC should a timer generate a spark when the advance lever is full advanced on the quadrant?

As I was working on the T today, I noticed my advance lever wouldn’t stay full advanced... it can be taken down the quadrant to that position but then it rebounds some. I looked at the end of my steering column and noticed it is because my commuter rod, when fully advanced, makes contact with the steering column then rebounds back a little when I let go of the advanced lever.

This made me think that I may not have an appropriate full range of motion of my timer, thus diminishing the performance of the engine.

So, question 2. Is there a table or guidelines to show what physical range of motion of the timer is sufficient to ensure the full range of timing which should be available to the engine? I measured mine today with masking tape on the engine and on the timer, making a mark at the beginning and end of that range. It was just over a half an inch.

I have attached pics of my commuter rod’s position at the extremes of the advanced rods positioning on the quadrant. If you look at the commuter rod in the retarded position... it appears it has more travel range possible as the physical connector could lean/travel more toward the steering column. If I took advantage of that range, then I could gain the unused range on the quadrant when the commuter rod is more advanced but butts against an obstruction then rebounds.

So question 3, how can I get that connector to sweep more toward the steering column when set in the retarded position? It seems that connector is held onto the rod passing though the steering column, and up to the advance lever, with a screw passing through the middle of the rod. So it seems like the connector cannot simply be made to rotate since the screw is holding it in a fix position.

I apologize for the lengthy post, this is something which would be more efficiently handled in a Model T club meeting. But we don’t have those right now.

Thank you for those who made it though this post. I’m still in a steep learning curve and hope this post didn’t sound too ignorant.

Thank you,
Darin

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Sun Dec 27, 2020 8:48 pm
by Humblej
Darin, The fully retarded spark lever should correspond to spark at or just past TDC. 15 deg is way too much. To answer your question #1, there is no corresponding degrees of advance for a fully advanced spark lever, it is the limits of the arms and spark rod. If you have the fully retarded position set to 15 deg past TDC then you have reduced the fully advanced position by about 15 deg. The only adjustment to make is to set for the fully retarded position. I remove the #1 spark plug and insert a long wire into the spark plug hole, crank the engine over and look for the wire to indicate just past TDC, then I rotate the timer to get a spark at the fully retarded lever position. For question #3, there is no way to adjust the position of the arm on the spark lever shaft short of bending the spark lever, the arm is pinned to the rod and is not intended to be adjusted. All adjustments are made by bending the rod that goes from the spark lever arm to the timer, and that adjustment is for the fully retarded position, not the fully advanced position. If your rod is binding on the steering shaft you can bend the rod to clear the interference and you will probably need to bend it elsewhere to set fully retarded/TDC.

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Sun Dec 27, 2020 9:13 pm
by Norman Kling
I agree with Humble. I would add a couple things. One would be excessive play in the linkage which would allow you to move the lever up or down without moving the timer. Try to get all the slack out. You might need to put a shim around the rod where it goes through the hole in the timer, and/or install a very thin washer. The other thing would depend on whether you are running on magneto and coils or on battery. When you run on battery, the spark will advance continually as you move the lever down. Whereas if you are running on magneto, you will find at least 3, sometimes 4 spark positions where your spark will advance and in between those positions, it will remain the same. Only if the coils are not set the same for each coil, you might find one or two coils more advanced than the others if you run right on the edge of one of those positions. When you drive the car, try to find the best position for the speed of the car. The faster the engine is running, the more advanced the spark should be set.
Norm

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Sun Dec 27, 2020 9:27 pm
by Art M
I plan to check the degrees of retard when the lever is in the full upright position. I will check the amount the timer advances when the lever is in the full downward position.
The results will be posted when I get the results. I have never checked the degree of retardation in 44 years of ownership.
In the past, it has been reported on forum that the degree of retardation changes when different brand timers are used.
I have noticed that my engine starts better when I pull the lever down by two notches before attempting to start the engine. Unfortunately I don't know how much the timer is retarded, but I will know the very soon.
Art Mirtes

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Sun Dec 27, 2020 10:01 pm
by Mark Gregush
What I am seeing is; the rod has been rebent and maybe not enough bend now to clear the steering shaft;
https://cdn.modeltford.com/i/c/2930425l.jpg

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Mon Dec 28, 2020 1:15 am
by Darin Hull
The reason I referenced setting 15 degrees after TDC was from reading on this forum and articles written on the T ignition system. I didn’t know if this was a Ford recommendation or simply a rule of thumb.

Jeff and Norman - Thank you for mentioning commuter rod slop and bending issues. I do have slop in it as the spark lever has to be moved a certain distance before it will actually move the timer. This slop is taking away from my T’s ability to advance the spark properly. After looking at the Lang’s catalog I believe I may not have the right commuter rod setup as I don’t have a swivel joint end... the rod is simply one solid piece of metal. Also, the spark rod lever has been previously repaired in a way which got the job done but adds to the slop. So, I’ve ordered a new commuter rod setup including spark rod lever and pin.

Art - I’ll be curious to hear your results.

Mark - I’ll see if this new setup clears the steering column. If not, I’ve noted the commuter rod would simply have to be bent due to the pinned lever.

Oh and due to a severely underperforming mag, I do run off a battery when driving the T.
Darin

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Tue Dec 29, 2020 9:25 am
by Original Smith
The photos above show the incorrect lever on the spark rod from the steering column. Where is the swivel, and the correct commutator rod?

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Tue Dec 29, 2020 10:09 am
by TWrenn
Darn it Larry, you took the words right outa my keyboard!! :lol:

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Tue Dec 29, 2020 10:32 am
by Darin Hull
Larry and Tim - 100% agree. I didn’t even pay attention to the commuter rod until this issue. I’ve already ordered the correct rod and swivel from Lang’s and it should be here soon.

Darin

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Wed Dec 30, 2020 7:11 am
by Ron Patterson
Darin
You may find this article helpful.
http://www.funprojects.com/pdf/Model%20 ... iticle.pdf
Ron Patterson

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Wed Dec 30, 2020 11:19 am
by Original Smith
Timer Gauges: Of course a ruler is an easy way to set the timing in the retarded position, but the timer gauge made by Snyder to do the setting is ONLY made for the late T's with a 5/8 bolt head. What about a gauge for a 9/16 bolt head? Does anyone have any data on when the bolt heads were changed from 9/16 to 5/8?

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Wed Dec 30, 2020 2:16 pm
by Humblej
Caution, the timer gauge measuring distance from a bolt head is only usable for an actual Ford timer with an actual Ford roller. You can tell a Ford timer and roller from an aftermarket by the Ford script, or lack thereof.

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Wed Dec 30, 2020 5:38 pm
by Ed Fuller
A few years back someone posted this method for setting timing. It has always worked well for me. It’s a Model T, don’t overthink it!

How to Time a Model T

1. Turn crank shaft around until crank pin is horizontal 


2. Turn key to Batt.

3. Retard spark 


4. No coils should be buzzing 


5. If coil buzzes go to step 8


6. Advance spark rod 3-5 clicks on quadrant a coil should buzz; If coil doesn’t begin to buzz go 
to step 9 


7. Retard spark, coil should stop buzzing everything okay! 


8. The timer control needs to be lengthened return to step 3

9. The timer control needs to be shortened return to step 3


10. Coil should buzz and quit buzzing every time you advance and retard the spark!

Re: 13T - Commuter Rod Travel Range and Its Impact on Timing

Posted: Wed Dec 30, 2020 10:37 pm
by MKossor
Darin, Proper Timer setting range is very important for safe cranking and optimal engine performance. Here is a link to illustrated instructions on how to verify initial spark setting 15 degrees After TDC with spark lever fully retarded and how to test for minimum adjustment range.

https://img1.wsimg.com/blobby/go/c3eb4b ... 3779027809

See Section 2, pages 6 to 9. Hope you find it useful.