{"product_id":"boise-boat-works-distributor-cap-rotor-tune-up-kit-for-mercruiser-4-3l-thunderbolt-i-iv-brass-terminals-gasket","title":"Boise Boat Works Distributor Cap \u0026 Rotor Tune-Up Kit for Mercruiser 4.3L — Thunderbolt I\/IV, Brass Terminals \u0026 Gasket","description":"\u003cp\u003e\u003cstrong\u003eA complete replacement distributor cap and rotor tune-up kit engineered to restore reliable spark for Mercruiser 4.3L V6 engines with Thunderbolt I and IV ignition systems (1985+).\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis Boise Boat Works kit contains the critical components you need to refresh the ignition on GM 4.3L Mercruiser V6 engines equipped with Thunderbolt I or Thunderbolt IV systems. Designed as a direct-fit replacement for part numbers 815407Q5, 815407A2, 18-5274, and 9-29317, the kit includes a new cap with brass terminals, a rotor, a gasket, and mounting bolts. Installing these parts helps eliminate wear-related misfires, poor starting, and uneven engine performance caused by aged distributor components.\u003c\/p\u003e\n\n\u003ch3\u003eWill this kit fit my Mercruiser 4.3L V6 engine?\u003c\/h3\u003e\n\u003cp\u003eYes — the kit is sized to replace factory distributor caps and rotors used on all GM 4.3L V6 Mercruiser engines that use Thunderbolt I or Thunderbolt IV ignition from 1985 onward. Confirm compatibility by matching your existing part numbers or visually comparing the cap and rotor style.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eReplaces OEM part numbers 815407Q5, 815407A2, 18-5274, 9-29317\u003c\/li\u003e\n  \u003cli\u003eFits Mercruiser V6 4.3L with Thunderbolt I and IV ignitions\u003c\/li\u003e\n  \u003cli\u003eIntended for engines from 1985 and newer\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow will installing this kit improve engine performance?\u003c\/h3\u003e\n\u003cp\u003eReplacing worn distributor parts restores accurate spark timing and consistent electrical contact, which often reduces hesitation, rough idling, and difficult starts. While not a cure-all for unrelated engine issues, a fresh cap and rotor eliminate a common source of misfires and uneven cylinder firing.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eBrass terminals provide reliable electrical conductivity\u003c\/li\u003e\n  \u003cli\u003eNew rotor ensures even distributor contact with plug wires\u003c\/li\u003e\n  \u003cli\u003eGasket and bolts included for a proper reseal and fit\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat comes in the kit and is installation difficult?\u003c\/h3\u003e\n\u003cp\u003eThe kit delivers everything required for a standard distributor cap and rotor service: the cap with brass contacts, rotor, a replacement gasket, and the mounting bolts. Basic hand tools and moderate mechanical experience are usually sufficient; the job is typically straightforward and can be performed in a garage or on the boat with simple instructions.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eIncluded: cap, rotor, gasket, mounting bolts\u003c\/li\u003e\n  \u003cli\u003eTools: screwdriver or socket set, basic ignition timing check tools if required\u003c\/li\u003e\n  \u003cli\u003eSkill level: intermediate DIY or professional mechanic for best results\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow can I confirm the part before ordering?\u003c\/h3\u003e\n\u003cp\u003eVerify by checking the part number on your current cap\/rotor assembly or compare the distributor’s electrical terminal layout to the product photos and diagrams. If your existing cap lists any of the replaced part numbers or your engine uses Thunderbolt I\/IV, this kit is the appropriate match.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eCompare OEM numbers printed on your old parts\u003c\/li\u003e\n  \u003cli\u003eMatch distributor terminal pattern visually\u003c\/li\u003e\n  \u003cli\u003eRefer to your engine service manual for Thunderbolt ignition details\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: Boaters, marine mechanics, and DIY enthusiasts who maintain Mercruiser-powered vessels with the 4.3L V6 and Thunderbolt I or IV ignition systems. If your boat shows signs of ignition wear — such as stalls, rough idle, or difficult starting — or you're performing routine tune-up maintenance, this Boise Boat Works cap and rotor kit provides the direct-fit parts to restore proper distributor function.\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: Does this kit replace OEM part 815407Q5?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. This Boise Boat Works kit replaces 815407Q5 and other equivalent Mercruiser part numbers for 4.3L Thunderbolt I\/IV systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I install the kit myself?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Many owners can install it with basic tools and mechanical knowledge; use service manual guidance or a mechanic if unsure.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"Boise Boat Works","offers":[{"title":"Default Title","offer_id":48084843397278,"sku":"B078PPPYK8","price":34.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/boise-boat-works-distributor-cap-front-view.jpg?v=1785863367","url":"https:\/\/northtrailauto.ca\/products\/boise-boat-works-distributor-cap-rotor-tune-up-kit-for-mercruiser-4-3l-thunderbolt-i-iv-brass-terminals-gasket","provider":"North Trail Auto","version":"1.0","type":"link"}