{"product_id":"ac-resistor-spark-plug-mr43t4-603-mr43t4","title":"ACDelco MR43T Marine Resistor Spark Plug | GM Inboard \u0026 Sterndrive","description":"\u003ch2\u003eACDelco Marine Resistor Spark Plug for GM Inboard \u0026amp; Sterndrive Engines\u003c\/h2\u003e\u003cp\u003eThe ACDelco MR43T is a marine-specific resistor spark plug for GM-based inboard and sterndrive engines. Like all ACDelco “MR” marine plugs, the built-in resistor suppresses radio frequency interference (RFI) to protect onboard electronics including GPS units, chartplotters, and VHF radios. The MR43T features a tapered seat design and is a distinct specification from the MR43LTS. Sold individually.\u003c\/p\u003e\u003ch3\u003eCompatible Applications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGM-based marine inboard and sterndrive engines requiring ACDelco MR43T spark plug\u003c\/li\u003e\n\u003cli\u003eMerCruiser, Crusader, and Indmar GM-block engines — verify OEM plug number before ordering\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eKey Features\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMarine-specific resistor design — suppresses RFI to protect onboard electronics\u003c\/li\u003e\n\u003cli\u003eTapered seat design — distinct from the MR43LTS (gasket seat)\u003c\/li\u003e\n\u003cli\u003eCopper core center electrode for reliable spark across a wide operating range\u003c\/li\u003e\n\u003cli\u003eSold individually\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eParts Desk Insights\u003c\/h3\u003e\u003cp\u003eThe MR43T is a standard marine resistor plug for GM-based inboard and sterndrive engines — the tapered seat is the key physical difference from the \u003ca href=\"\/products\/ac-resistor-spark-plug-mr43lts-603-mr43lts4\"\u003eACDelco MR43LTS\u003c\/a\u003e, and the two are not interchangeable. Always verify your engine’s OEM plug specification before ordering, as using the wrong seat type can cause improper sealing and heat transfer issues. The resistor is required on marine engines to prevent ignition noise from interfering with navigation and communication electronics. It’s the right plug for routine tune-ups on compatible GM marine engines and a reliable baseline before considering an upgrade to platinum or iridium.\u003c\/p\u003e","brand":"LNS","offers":[{"title":"Default Title","offer_id":51250814550052,"sku":"603-MR43T4","price":8.29,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/bac3d2f3-4334-4172-8e76-9810c46e26c4.png?v=1787203198","url":"https:\/\/marisolmarine.com\/products\/ac-resistor-spark-plug-mr43t4-603-mr43t4","provider":"Marisol Marine Company","version":"1.0","type":"link"}