Mercury - Quicksilver 811635T3 Distributor Cap GM 4-Cylinder Engines Delco EST Ignition 811635T3. Overview. A reliable start and a steady idle depend on a clean, consistent spark - and that begins right at the distributor. The Quicksilver 811635T3 Distributor Cap is the genuine OEM replacement for marinized GM 4-cylinder MerCruiser engines equipped with Delco EST ignition systems. It's the same cap Mercury installs at the factory, built to withstand the heat, vibration, and moisture that come wi