| When we couldn't get the stroker motor in the
Coronet to stop backfiring we went looking for the problem. Eventually
we figured out that the vacuum advance in the Mopar Performance
distributor was swinging the rotor out of position enough to cause the
spark to jump to the wrong tower. Since there wasn't any easy way to
adjust the rotor phasing in the distributor, we created this part. This
reluctor has been CNC machined so that you can advance or retard the
position of the rotor in relationship to the distributor cap. This will
allow you to have the rotor pointed directly at the tower when the
spark plug fires. There is no other way to adjust the rotor phasing in
the MP distributors. There is an easy test to see if you need this
part. Drill a hole in your distributor cap near the #1 tower. Start up
the engine and shine your timing light down that hole which you just
drilled. You should see the rotor every time that the timing light
shines. If the rotor is pointed directly towards the #1 tower then your
system is phased just fine. However, if the rotor is ahead, or behind
the tower then you might want to consider phasing the rotor. Be sure to
check the rotor position at full vacuum advance as that is where the
problem usually occurs. To do this you'll need to attach a small vacuum
source such as a MityVac to the vacuum advance port on the distributor.
Shine the timing light down in to the distributor with the engine
running while you apply vacuum to the advance mechanism. You'll see the
rotor twist backwards towards the #2 tower! If it twists back too far
the motor will start to backfire as the spark gets 90 degrees out of
phase. If your motor is doing this then you need to phase the rotor. |
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