The Opti-spark distributor is positioned on the front of the engine underneath the water pump, and works well in its designed environment--when it works. It isn't a matter of if your Opti-spark will give you problems; it's a matter of when. When the Opti-spark first came out in 1992, it was part of a new engine package dubbed the LT1. This engine was a definite improvement over the L98, and the Opti-spark was part of the package.
The problem arises when the water pump begins to leak and the seals in the distributor begin to deteriorate, or water begins to condense inside the distributor. From the beginning, the engineers had the forethought to include small drain holes in the bottom of the distributor, but they weren't as effective as they were intended to be. In 1995 and 1996 the Opti-spark distributor was changed to include a vacuum vent to help remove any moisture that might have formed inside the distributor.
The problem is that you can't replace the older-style distributor with the newer style without tearing apart the front of the engine because of the differences in the drive assembly of the distributor. Changing to the newer Opti-spark would entail changing the timing cover and the locating pin in the camshaft.
Chris Petris at Corvette Clinic has come to the rescue, so we can walk you through a step-by-step solution to this problem with the older Opti-spark distributors. Chris says he has yet to see one of his reworked Opti-spark distributors return with a problem.