Ford Manual
What about the Spark Plugs?
Answer No. 60
One is located at the top of each cylinder and can easily be taken out with the spark plug wrench
included with every car, after the wire is disconnected. The high voltage current flows out of the
secondary coils in the coil box and on reaching the contact points in each spark plug it is forced to jump
a gap, thereby forming a spark which ignites the gasoline charge in the cylinders.
The spark plugs should be kept clean (i.e., free from carbon) and should be replaced if they persist in not
working properly. There is nothing to be gained by experimenting with different makes of plugs. The
make of plugs with which Ford engines are equipped when they leave the factory are best adapted to the
requirements of our motor, notwithstanding the opinion of various garage men to the contrary. All wire
connections to spark plugs, coil box and commutator should, of course, at all times be kept in perfect
contact.
What are the indications of Ignition trouble?
Answer No. 61
The uneven sputter and bang of the exhaust means that one or more cylinders are exploding irregularly
or not at all, and that the trouble should be promptly located and overcome. Misfiring, if allowed to
continue, will in time damage the engine and the entire mechanism. If you would be known as a good
driver you will be satisfied only with a soft, steady purr from the exhaust. If anything goes wrong, stop
and fix it if possible---don't wait until you get home.
How can one tell which Cylinder is missing?
Answer No. 62
This is done by manipulating the vibrators on the spark coils. Open the throttle until the engine is
running at a good speed and then hold down the two outside vibrators, No. 1 and No. 4, with the fingers,
so they cannot buzz. This cuts out the two corresponding cylinders, No. 1 and No. 4, leaving only No. 2
and No. 3 running. If they explode regularly it is obvious the trouble is in either No. 1 or No. 4. Relieve
No. 4 and hold down No. 2 and No. 3 and also No. 1; if No.4 cylinder explodes evenly it is evident the
misfiring is in No. I. In this manner all of the cylinders in turn can be tested until the trouble is located.
Examine both the spark plug and the vibrator of the missing cylinder.
If the Coil and Plug are right---what?
Answer No. 63
The trouble is probably due to an improperly seated valve, worn commutator, or short circuit in the
commutator wiring. Weakness in the valves may be easily determined by lifting the starting crank slowly
the length of the stroke of each cylinder in turn, a strong or weak compression in any particular valve
being easily detected. It sometimes happens that the cylinder head gasket (packing) becomes leaky---
permitting the gas under compression to escape, a condition that can be detected by running a little
lubricating oil around the edge of the gasket and noticing whether bubbles appear or not.
Does a worn Commutator ever cause misfiring?
Answer No. 64
