Hudson Super Six 1916, Reference Book

Page: 57 / 77

On account of the great heat to which these porcelains are subjected, breakage is quite frequent, and the
length of the electrode in such a plug would certainly cause pre-ignition.
Another disadvantage of the long electrodes is that they distort and warp under high temperatures and vary the
gap from the correct setting.
Any type of plug which has a large, solid porcelain and small short electrodes will be satisfactory if the shell
does not project into the combustion chamber farther than the standard plug supplied with our cars.
The correct gap for the standard plug on the Hudson Super-Six is from .025" to .028".
Symptoms of pre-ignition are, back-firing in the carburetor and missing under a heavy pull, especially on long
hills where the constant load has a tendency to heat the motor above normal temperatures.
If the electrodes are being warped out of place by this heating, the missing will continue. After an experience
of this kind, it will be necessary to remove the spark plugs and reset them. This will be only a temporary relief for
they will develop the same trouble the next time they are subjected to a long pull or a slight over-heating, The
remedy is, use the correct type of plug.
To Time the Ignition
Set the spark lever on the steering wheel at the top and see that the advance rod which connects the generator
advance lever and sector gear at the base of the steering box is not too long so as to bind the distributor advance
ring in the generator.
This rod should be adjusted so that the yoke end fits into the generator advance lever without any binding
when the hand lever on the steering gear is fully advanced. The distributor advance ring will wear rapidly if this
adjustment is not properly taken care of.
Open the priming cocks on the motor, turn slowly by hand, using starting crank until No. 1 cylinder starts to
blow. This indicates that this cylinder is on its compression stroke. To determine this, hold your finger over the
priming cock.
No. 1 cylinder is due to fire in advance position when the mark "A" on the flywheel reaches the pointer
attached to the crank case. This may be observed through the inspection hole on the flywheel housing left side
motor. Mark "A" is 1/2" before top center. (Top center is marked D-C-1 1/2" 6.)
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The plugs that are fitted at the factory are
of a type calculated to give the maximum
amount of satisfaction, and we are positive
that they will not cause pre-ignition under any
conditions. While we do the particular t y p e
of plug not insist on our owners using which
we use, we recommend that they consider the
above points when purchasing plugs for their
cars.