{"product_id":"aa-ignition-replacement-inboard-coil-for-mercruiser-thunderbolt-iv-v-hei-systems","title":"AA Ignition Replacement Inboard Coil for MerCruiser Thunderbolt IV\/V HEI Systems","description":"\u003ch2\u003eOverview\u003c\/h2\u003e\n\u003cp\u003eReliable ignition is essential for smooth engine operation on marine projects. The AA Ignition Replacement Inboard Coil is designed to deliver a clean, consistent spark for inboard engines that use MerCruiser Thunderbolt IV or V ignition systems with HEI. If your boat has shown signs like hard starting, reduced power when the engine heats up, or erratic running, a high-quality replacement coil can help restore driveability without guessing at the root cause.\u003c\/p\u003e\n\u003cp\u003eThis coil is built as a direct, OEM-like replacement, crafted to resemble the factory part in fit and finish. It sits alongside the distributor and is intended for boats that rely on HEI systems. The goal is to provide a practical upgrade option that aligns with original design while offering the confidence of a robust aftermarket alternative.\u003c\/p\u003e\n\n\u003ch2\u003eCompatibility and Installation\u003c\/h2\u003e\n\u003cp\u003eDesignated for MerCruiser GM V6 and V8 engines equipped with Thunderbolt IV and V ignition systems, this coil works exclusively with HEI (High Energy Ignition) setups and will not operate with Point Ignition configurations. It replaces a broad set of part numbers (including 18-5438, 392-805570A2, 392-7803A4, 392-805570A1, 72115, 40511) and is intended to restore proper spark and fuel ignition in supported engines.\u003c\/p\u003e\n\u003cp\u003eThough not a genuine OEM part, the coil is a direct replacement that mirrors the factory part’s fit and performance. This means a straightforward swap, with the potential to save time and money versus dealer options, while maintaining a familiar installation footprint beside the distributor.\u003c\/p\u003e\n\n\u003ch3\u003eWhat You Get and How It Helps\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eReplaces worn or failed ignition coils to re-establish a reliable spark, aiding cold and warm starts.\u003c\/li\u003e\n  \u003cli\u003eSupports MerCruiser Thunderbolt IV and V HEI systems for consistent engine behavior under load and at idle.\u003c\/li\u003e\n  \u003cli\u003eOEM-like quality and finish provide a familiar look and fit for straightforward DIY maintenance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul\u003e\n  \u003cli\u003ePotential improvements in throttle response and driveability by maintaining steady ignition performance.\u003c\/li\u003e\n  \u003cli\u003eDesigned for dependable operation with inboard marine engines, reducing the risk of misfires caused by aging components.\u003c\/li\u003e\n  \u003cli\u003eTwo-year or 24,000-mile warranty offers assurance and a path to replacement if needed.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eQuality, Warranty, and Buying Confidence\u003c\/h2\u003e\n\u003cp\u003eAA Ignition backs this coil with a two-year or 24,000-mile warranty. If the coil fails within the coverage period, you can request a replacement per the warranty terms. This part is intended to deliver OEM-style reliability and a cost-conscious alternative to dealer parts.\u003c\/p\u003e\n\u003cp\u003eBefore purchase, verify that your engine configuration matches a Thunderbolt IV or V HEI ignition setup. This helps ensure a correct match and optimal performance for your MerCruiser inboard system. While not a genuine OEM component, the coil is designed to closely mirror factory specs for compatibility and ease of installation.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: What engines is this coil compatible with?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Designed for MerCruiser GM V6 and V8 engines using Thunderbolt IV or V HEI ignition systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: What warranty does this replacement coil include?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: 2-year or 24,000-mile warranty; free replacement if the coil fails within coverage.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"AA Ignition","offers":[{"title":"Default Title","offer_id":42470652313685,"sku":"B07GL4TM27","price":42.67,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0632\/3270\/4597\/files\/aa-ignition-replacement-ignition-coil-mercruiser-thunderbolt-iv.jpg?v=1778141105","url":"https:\/\/plentytorque.co.uk\/products\/aa-ignition-replacement-inboard-coil-for-mercruiser-thunderbolt-iv-v-hei-systems","provider":"PlentyTorque","version":"1.0","type":"link"}