Spark Plugs for the Model A

By Wayne Russert

At the 2007 Wichita Regional an ignition seminar was presented

and the following spark plug info was handed out.

Recommended spark plugs for the Model A:

Reproduction. Champion 3X - $27

Champion W18 (Equal to Champion 3X - $13

Autolite 3076 (Hotter than W16Y) - $2.50

Motorcraft TT10 (Same as 3076) - $4

NOT Recommended for the Model A:

Champion C-4 (Ref. Ford S/B Aug. 1932)

Champion W16Y (Equivalent to C-4) (Too cold) - $9

900 – 1500 deg. F. is the optimum heat range for plugs.

A 10 deg. spark advance from a particular advanced position will raise plug temperatures by 150 – 200 deg. F. For example assume that you have advanced the lever to a 20 deg advanced position and the engine is running at a certain plug temperature, then further advance the spark 10 degrees to a 30 degree advanced position (about full advance), then the plug temperature will go up an additional 150 to 200 degrees.

Reduce plug gap to .030” with 5.5 of higher compression ratio.

The insulator nose length of a Champion 3X is 0.875”. Just right for the “A”.

Note: The reproduction 3X plugs have a terminal nut that is smaller than original; however, all the “A” supply houses carry the correct nuts for a few cents each.

I cannot verify the above data but want to pass it along.

I have been running a set of Champion W16Y plugs in our coupe for several years and they do show deposits that indicate they are too cold.

If you have experience with any of these plugs, pro or con, please pass it along for the benefit of all club members.

Wayne