{"product_id":"sierra-18-8821-1-spark-plug-wire-set-for-mercruiser-8-cylinder-v8-engines-with-thunderbolt-ignition","title":"Sierra Spark Plug Wire Set 18-8821-1 for Mercruiser 260, 300, 320 EFI, 350 Mag Alpha Thunderbolt IV 8-Cylinder Engines","description":"\u003cp\u003eThe Sierra 18-8821-1 Spark Plug Wire Set is a complete 8-cylinder ignition wiring kit built for Mercruiser stern drive engines equipped with a Thunderbolt IV distributor. The set includes eight spark plug wires plus a coil wire, all terminated with corrosion resistant stainless steel spark plug and distributor terminals for reliable conductivity in the marine environment. Spark plug wire lengths are (2) 29 inches, (2) 34 inches, (2) 38 inches, and (2) 44 inches, with a single 12 inch coil wire, giving the correct reach for routing around an 8-cylinder Mercruiser block without excess slack or strain on the terminals.\u003c\/p\u003e\u003cp\u003eThis wire set is engineered to meet or exceed the performance of the original equipment wiring it replaces, built to withstand heat, vibration, moisture, and salt exposure typical of marine ignition systems. It is designed as a direct fit for the Mercruiser 260, 260 MIE, 300, 320 EFI, and 350 Mag Alpha engines listed below, all of which use the Thunderbolt IV distributor on an 8-cylinder configuration.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-8821-1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Stainless Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Spark Plug Wires:\u003c\/strong\u003e 8\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpark Plug Wire Lengths:\u003c\/strong\u003e (2) 29 inches, (2) 34 inches, (2) 38 inches, (2) 44 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoil Wire Length:\u003c\/strong\u003e 12 inches (1)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTerminal Type:\u003c\/strong\u003e Corrosion resistant stainless steel spark plug and distributor terminals\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDistributor Type:\u003c\/strong\u003e Thunderbolt IV\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Configuration:\u003c\/strong\u003e 8 Cylinder\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Dimensions:\u003c\/strong\u003e 10.25 x 7.25 x 2.75 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 2 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282194499\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercruiser 260, 8 Cylinder, Thunderbolt IV distributor, 1982 to 1987\u003c\/li\u003e\n\u003cli\u003eMercruiser 260 MIE (LH), 8 Cylinder, Thunderbolt IV distributor, 1981 to 1986\u003c\/li\u003e\n\u003cli\u003eMercruiser 260 MIE (RH), 8 Cylinder, Thunderbolt IV distributor, 1981 to 1986\u003c\/li\u003e\n\u003cli\u003eMercruiser 300, 8 Cylinder, Thunderbolt IV distributor, 1985 to 1986\u003c\/li\u003e\n\u003cli\u003eMercruiser 320 EFI, 8 Cylinder, Thunderbolt IV distributor, 1987 to 1989\u003c\/li\u003e\n\u003cli\u003eMercruiser 350 Mag Alpha, 8 Cylinder, Thunderbolt IV distributor, 1986 to 1994\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-8821-1 spark plug wire set fit?\u003c\/strong\u003e It fits Mercruiser 8-cylinder engines equipped with a Thunderbolt IV distributor, specifically the 260, 260 MIE (LH and RH), 300, 320 EFI, and 350 Mag Alpha models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many wires are included in this set?\u003c\/strong\u003e The 18-8821-1 set includes 8 spark plug wires plus 1 coil wire, enough for a complete 8-cylinder ignition wiring job.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the individual wire lengths?\u003c\/strong\u003e Spark plug wire lengths are (2) 29 inches, (2) 34 inches, (2) 38 inches, and (2) 44 inches, with a single 12 inch coil wire.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material are the terminals made from?\u003c\/strong\u003e The 18-8821-1 set uses corrosion resistant stainless steel spark plug and distributor terminals for reliable conductivity in the marine environment.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this wire set work with a Thunderbolt IV distributor?\u003c\/strong\u003e Yes, the Sierra 18-8821-1 is specifically designed for Mercruiser engines using the Thunderbolt IV distributor.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this fit a Mercruiser 260 MIE with a serial number in the 5907058 to 0B788151 range?\u003c\/strong\u003e Yes, both the left-hand (LH) and right-hand (RH) 260 MIE Thunderbolt IV engines with serial numbers 5907058 through 0B788151 use the 18-8821-1 wire set.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat year range does this part cover for the Mercruiser 350 Mag Alpha?\u003c\/strong\u003e For the 350 Mag Alpha with Thunderbolt IV distributor, the 18-8821-1 covers 1986 to 1994.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e The 18-8821-1 is a genuine Sierra part, manufactured to meet or exceed the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the weight of this spark plug wire set?\u003c\/strong\u003e The Sierra 18-8821-1 spark plug wire set weighs 2 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-8821-1 fit the Mercruiser 320 EFI?\u003c\/strong\u003e Yes, it fits the Mercruiser 320 EFI with a Thunderbolt IV distributor, covering serial numbers 0A543604 to 0C622418 from 1987 to 1989.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAre the wires resistant to corrosion in a marine environment?\u003c\/strong\u003e Yes, the terminals on the 18-8821-1 set are corrosion resistant stainless steel, built to withstand the marine environment's heat, vibration, and moisture.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included with the 18-8821-1 kit?\u003c\/strong\u003e The kit includes the complete 8-cylinder spark plug wire set: 8 spark plug wires and 1 coil wire for a Mercruiser Thunderbolt IV ignition system.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988435218651,"sku":"SIE-18-8821-1","price":66.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/Untitled-1__75469.1753840690.500.750.jpg?v=1785189165","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-8821-1-spark-plug-wire-set-for-mercruiser-8-cylinder-v8-engines-with-thunderbolt-ignition","provider":"Good Vibes Marina","version":"1.0","type":"link"}