{"product_id":"holley-efi-gen-iii-hemi-coil-harness-early-coils-558-310be","title":"Holley EFI Gen III HEMI Early Coil Harness: Chrysler 300 (05-15) \/ Dodge Ram 1500 (03-10)","description":"\u003ch3\u003eHolley EFI Gen III HEMI Early Coil Harness\u003c\/h3\u003e\u003cp\u003e2003–2018 Chrysler 5.7L \/ 6.1L \/ 6.4L HEMI Engines\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003e558-310\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eOverview:\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe Holley EFI Gen III HEMI Early Coil Harness is engineered specifically for Chrysler’s 5.7L, 6.1L, and 6.4L HEMI engines produced between 2003 and 2018. Designed to work with the early coil style that requires spark plug wires, this harness enables precise control over fuel and spark timing when paired with Holley EFI systems. Ideal for enthusiasts upgrading their Gen III HEMI engines or performing engine swaps, it provides the foundation for advanced tuning capabilities and enhanced engine management.\u003c\/p\u003e\u003cp\u003eThis harness is perfect for those seeking to maximize performance with power adders such as nitrous oxide, superchargers, or turbochargers, and it supports alternative fueling methods including methanol and water injection. With Holley EFI’s cutting-edge technology, users gain full command of their engine’s fuel delivery and ignition timing for optimized power and efficiency.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eKey Features:\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eBuilt to meet the demands of high-performance Gen III HEMI engines, this harness offers reliable connectivity and durability. Key features include:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eDesigned specifically for early coil setups on 5.7L, 6.1L, and 6.4L Gen III HEMI engines (2003–2018)\u003c\/li\u003e\n\u003cli\u003eEnables full control of fuel and spark timing with Holley EFI systems\u003c\/li\u003e\n\u003cli\u003eCompatible with power adders such as nitrous, superchargers, and turbochargers\u003c\/li\u003e\n\u003cli\u003eSupports methanol and water injection tuning strategies\u003c\/li\u003e\n\u003cli\u003eTXL grade copper wiring for minimal weight and high-temperature resistance\u003c\/li\u003e\n\u003cli\u003eFactory-style terminations ensure secure, reliable connections\u003c\/li\u003e\n\u003cli\u003eOEM-grade connectors provide precise, positive fitment\u003c\/li\u003e\n\u003cli\u003eHarness routed through split-loom braid for protection and clean appearance\u003c\/li\u003e\n\u003cli\u003eSimple identification of coil type via plug wire requirement for easy installation\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eConstruction \u0026amp; Design:\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe harness is constructed using premium TXL grade copper wiring, known for its excellent conductivity and lightweight properties. This wiring is encased in a high-temperature sleeve with a small diameter to reduce bulk and improve routing flexibility within the engine bay. The use of factory-style terminations and OEM-grade connectors guarantees a secure, vibration-resistant connection that matches or exceeds factory standards.\u003c\/p\u003e\u003cp\u003eRouting through a split-loom braid not only protects the wiring from abrasion and heat but also delivers a professional, clean look that complements the engine bay. Every aspect of the harness is engineered to fit the Gen III HEMI engine platform precisely, ensuring a hassle-free installation and long-lasting performance.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eInstallation \u0026amp; Fitment:\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThis harness is designed for direct fitment on Chrysler Gen III HEMI engines equipped with the early coil style, which requires spark plug wires. Identification is straightforward: if your coils require spark plug wires, this is the correct harness. Installation involves connecting the harness to the engine’s coil and ignition system, with no modifications necessary for compatible vehicles. This plug-and-play design simplifies upgrades and engine swaps while maintaining OEM-level reliability.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat's Included:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eHolley EFI Gen III HEMI Early Coil Harness (Part #558-310)\u003c\/li\u003e\n\u003cli\u003eOEM-grade connectors pre-installed\u003c\/li\u003e\n\u003cli\u003eSplit-loom protective braid covering the wiring\u003c\/li\u003e\n\u003cli\u003eDetailed installation instructions\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eIdeal For:\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThis harness is ideal for automotive enthusiasts, professional tuners, and engine builders working with Chrysler Gen III HEMI engines from 2003 to 2018. It is especially suited for those upgrading to Holley EFI systems, performing engine swaps, or adding power enhancements such as forced induction or nitrous oxide. The harness provides the necessary wiring infrastructure to unlock advanced fuel and ignition control, enabling precise tuning and improved engine performance.\u003c\/p\u003e","brand":"Holley EFI","offers":[{"title":"Default Title","offer_id":47315668336852,"sku":"558-310","price":172.75,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0660\/8542\/1268\/files\/3453_96defc7d7eb6f1c498d3a08553027581674fc96c_9fc8dcfd-5de6-4db2-b97c-ed813838d9ab.webp?v=1766655092","url":"https:\/\/fasthemis.com\/products\/holley-efi-gen-iii-hemi-coil-harness-early-coils-558-310be","provider":"FastHemis","version":"1.0","type":"link"}