That famous spark & thottle chart

[Steve Jelf]

This diagram from Murray Fahnestock shows up often on the internet. I believe it refers to driving on battery, not mag. Is that right?

[Kerry]

Shouldn't be, Ford never recommended driving on battery, always turn key to magneto as soon as car started in the electric starter /battery model instruction books.

[Chris Barker]

It cannot be correct for the timing lever when driving on magneto.
You only have 3 (maybe 4) choices, and one of those is after TDC, so fine adjustments to the timing lever do nothing. And some of the positions shown will probably be between the output peaks and give poor running.

I have always wondered about this diagram, especially as it was published before it became usual to have the 'batt' option.

[Norman Kling]

Those positions will work fine on magneto when the fully retarded timing is properly set. You will find that the positions are right in the center of each "node". I refer to a node as the position where moving the lever does nothing and then moving it one more notch it will advance to another node, then farther advance a few notches to the next node etc. If you are sufficiently retarded with the lever all the way up and there is little play in the mechanism you will get four positions. However if the linkage is worn you might only get 3 or less positions.
When running on battery, you will advance the spark with every notch of the spark lever because the spark comes when the roter hits the contact on the cap. However it takes f few microseconds for the current to build up in the magneto, so the spark will not advance with every movement of the lever, because it depends upon the position of the magnets to the coils to advance the spark. You need the connection of the timer at the same time the current builds up in the magneto to get the plugs to spark. I hope i have made this clear. It is clear in my mind, however, a little hard to explain in words.
Norm

[AndreFordT]

Steve,

In the November-December Model T Times 2003 there is an article by Ron Patterson & Steve Coniff:

"The Model T Ignition System and Spark Timing"

In this article all is clearly explained and make me understand, at that time, that the only way to set the coils right is to use a HCCT.
As I am a low budget Model T-er I build my own HCCT out of Wood and old transmission parts. It is still in use and set coils and coils and coils ... since than.

I have the article in PDF form and can try to send you a copy.
Sharing it on this forum, it should be done by Ron or Steve.

Andre
Belgium

[Erik Johnson]

That chart is actually from the Victor Page book, The Model T Ford Car, Its Construction, Operation and Repair.

It's Fig. 38 and the centerfold in my 1917 edition of the book.

If you saw a full scan or had the actual book in your posession, you would see the following on the bottom:

"Fig. 38. Chart Showing Positions of Engine Control Levers on Steering Post Quadrants for Various Conditions or Car Operation. These are the Average Positions and May Vary Slightly on Different Ford Cars."

[Bud Delong]

I never thought much of that chart and the way some experts played with the spark lever. A position for battery starting one for starting on mag, and the sweet spot when running?? Bud.

[Steve Jelf]

That chart is actually from the Victor Page book, The Model T Ford Car, Its Construction, Operation and Repair.

I sit corrected. I'll make a note of that.

[NealW]

I sit corrected. I'll make a note of that.

It's in Murray's book too, but as pointed out, appeared first in Page's book.

[J1MGOLDEN]

Steve, now post the one that shows the Vehicle Speed relation to engine RPM.

I can't find it again.

[Steve Jelf]

https://www.nwvs.org/Technical/MTFCA/Ar ... eSpeed.pdf

[J1MGOLDEN]

Thanks Steve!

I was on several tours with Ted, he was born in Maine and always came back there for summer visits.

I have both of his books!

A great guy, with one bad habit, Camels.

His green pickup lives in Belair, Maryland now.