V-8 Spark Plug Wire Set | Sierra 18-8804-1 Sierra 8mm ignition wire set fits Mercruiser 454 and 502 CID marine engines with Thunderbolt distributors. Thunderbolt big block plug wire set Fits Mercruiser 454 and 502 cu. in. marine engines from 1982-98 with Thunderbolt ignition systems 90 degrees female boot at distributor and spark plug ends 12 in. coil wire Durable stainless steel wound conductor for maximum horsepower and engine performance 8mm blue premium silicone jacketing for the ultimate in high temperature protection Superior RFI suppression for the most sensitive electronic system Corrosion resistant stainless steel plug and distributor terminals for maximum conductivity Replaces Mercury 84-43376A2, 84-816608Q61, 84-42841A5, 84-43376A14, 84-43376A1, 84-43376A2, 84-813720A2,84-816761A15, 84-816608A61 Replaces Mallory 9-28001, 9-28002 Replaces Sierra 18-8804