Spark Advance - Why do I have to advance it all the way?

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Model T Ford Forum: Forum 2018: Spark Advance - Why do I have to advance it all the way?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dunlap - Orlando, Florida on Friday, February 23, 2018 - 09:09 pm:

On the 1922 Centerdoor we are working on for a friend, I have to advance the spark all the way (about to the 6 o’clock to 7 o’clock position). On my 1924 Coupe, I have to retard it a lot to keep it from taking off like a race horse. On my 1926 Roadster Pickup, the car runs great with the spark advanced to the 8 o’clock position.

We are still trying to tweak the carburetor and the timing to make this car run right. I am concerned that I am having to run the Centerdoor with the spark fully advanced when I am not really doing anything that would justify advancing it so far.

I know every car has its own sweet spot for where it runs best, but I don’t think the spark should be advanced all the way for normal driving.

The commutator is adjusted according to the directions in paragraph 126 of the Ford Service Manual.

Any thoughts on what might explain the need for fully advancing the spark?

Is there a remedy we are overlooking?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, February 23, 2018 - 09:30 pm:

The position in which the spark runs the best is controlled by the initial adjustment at full retard. All timers are not the same. The service manual has the instructions for setting the original Ford timer. If you have an aftermarket timer, you need to adjust so the spark comes just after the piston passes top dead center. To do this you must first determine where top dead center is. On most cars this occurs when the pin through the front pulley is horizontal. So you should turn the crankshaft to where the pin is just few degrees lower on the right side as you face the front of the engine. Remove the rod and turn the timer counter clockwise till the coil stops buzzing and then turn clockwise to where it just starts to buzz. It doesn't matter which coil buzzes because they each buzz when the pin is just past center. Now bend the rod so that it just fits into the timer when the spark lever is all the way up. Install cotter pins. I like to rotate the crank slowly after making this adjustment to be sure that each coil buzzes after the piston starts down. This would be just aftern the pin drops past horizontal. If you did this right, the engine will start without a kick when the lever is all the way up and will run fastest and smoothest about the 8:00 position.

If you are running on magneto, you will find what I call nodes where you can move the lever without changing the speed of the engine, then move it a little more and the engine will speed up. There should be 3 or sometimes 4 "nodes". As you drive the car, find the node where it runs best for driving conditions and speed.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, February 23, 2018 - 09:37 pm:

I didn't see your other post about the magneto. You will need to advance the spark farther when running on battery than on magneto, so there might be nothing wrong with your timer adjustment.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren F Rollins on Saturday, February 24, 2018 - 08:40 am:

I had some questions this week on the subject and was referred by Ron Patterson to an article that he and Steve Coniff wrote a few years back. The Model T Ford Ignition System and Spark Timing. Google it by title . Good and Informative read


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Saturday, February 24, 2018 - 11:42 am:

Eric
As Norman points out it appears the "initial timing" on your Model T is not set correctly.
Read this article and give me a call to explain how to correct this problem.
Model T Ford Ignition System and Spark Timing


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Saturday, February 24, 2018 - 11:44 am:

Eric
Sorry wrong article.
Here is the link again: Model T Ford Ignition System and Spark Timing


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dunlap - Orlando, Florida on Saturday, February 24, 2018 - 08:52 pm:

Thanks for the input.

I went out today determined to look at things differently and, by golly, it worked. I remeasured the distance for the commutator rod and realized it was at 2 3/4 inches, not the 2 1/2 inches that is recommended in the service manual.

I made an adjustment to the rod that got me spot on with 2 1/2 inches and that made a noticeable difference in the timing of the car. It ran considerably smoother.

It still is not real happy on magneto. We will sort out that problem after receiving some input from Ron Patterson.

Norm, I will likely try your recommendation once we determine the health of the magneto. I don’t want to start tweaking things too much until we know we have a mag that is working properly.

Thanks again for the input.


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