Ignition Timing Tool

[7355hpchry]

Where can a person get the timing tool for a 1973 Chrysler 55HP?? It is Part # T-2937-1, it threads into the top Spark plug hole and establishes 32* BTDC.

 

[Matthew A.]

Re: Ignition Timing Tool

You may have to make one as these parts are very hard to come by. Building one is fairly easy should you decide to do so using an old spark plug, a piece of wire and the use of an accurate and flexible ruler or tape measure to measure degrees [in inches] from TDC. Most user manuals should state what the measurement equivalent is in inches to figure degrees when measured on the flywheel.

 

[Frank Acampora]

Re: Ignition Timing Tool

Go to the public library and look for the INTERTECH manual for engines over 25 horsepower. In there they give the exact measurement for 36 degrees. I forget the exact amount, but it is something like .265 or .285 inches from TDC. The reason you use 36 degrees is because at TDC the crank CAN move a couple of degrees without the piston moving noticably. SO, you measure down to (.265 for example,) and use that as the reference point. 36 is far enough to be accurate, yet close enough to be useful. Simply use a depth gauge and measure the difference between the setting at TDC and (.265) through the spark plug hole.

BTW: the 125 and 140 use a longer stroke crankshaft and the measurment is something like .312 inch.

I'll bet you always wondered why 36 degrees was on the flywheel when the engine is timed at 32. Now you know.

Note that on later Force engines, they gave this up. Possibly because better manufacturing tolerances on the keways made it more precise to set the flywheel at 0 degrees and the 36 degrees unnecessary.

My experience has been that the tool is not necessary. After you try feeling TDC through the plug hole a couple of times or more by rocking the flywheel, you will be quite accurate enough.