Been haveing a bit of a rough running engine and then suddenly  cylinder
#4 stopped doing its share of pushing. Investigation revealed a dead
short in the plug shield. In low light you could see an arc everytime
the rotor reaching firing position. So, possibly tune up time.

I replaced the ignition harness with new wires - Bosch Kit - and new
Bosch plugs, rotor and distributor cap. These latter were well used.
After some fiddling and farbleing, She started right up and ran good. I
did not reset the timing, though I shall shortly.

Driving around today I could feel just the faintest little erratic
twitch in the operation of the engine. On the way home there is a hill
with a long grade that rises several hundred feet. With the speedo
pegged at 58, RPM at 3000, petal to the metal, I got suspicious, and
pulled to the center lane where the highway divider was a concete wall.
Voila!!! Spark Rattle, loud and clear. Backed off the gas and it still
rattled.  I drove down through a small canyon on the back road to my
place, and even on flat ground, down between the rock walls I could hear
that ominous sound.

So, my question is how to approach finding and fixing this. Don't want
to burn this engine up, so must locate this.

Any input is appreciated.

John Rodgers
88 GL Driver