BIGLKNM Thermostat Housing Water Neck for Mopar V‑8 318–440 Billet Aluminum Direct‑Fit with Gasket & Screws

BIGLKNM billet aluminum water neck thermostat housing built to fit Mopar V‑8 engines from 1957–1980, providing a durable, corrosion-resistant replacement with included gasket and stainless screws.

Restore coolant routing and top-end sealing on classic Chrysler, Dodge, and Plymouth V‑8s with a precision-machined thermostat neck engineered as a direct-fit service part. This assembly replaces aging cast or cracked housings on small- and big-block Mopar motors — including popular displacements such as 273, 318, 340, 360, 361, 383, 400, 413, 426W and 440 — and arrives with the hardware needed for a straightforward install.

Which Mopar engines and years will this thermostat housing work with?

Designed to match original mounting points and coolant passages, the housing fits a wide range of Mopar V‑8 engines produced between 1957 and 1980. Confirm compatibility by comparing the flange and bolt pattern with your existing housing before ordering.

• Compatible engines: 273, 318, 340, 360, 361, 383, 400, 413, 426w, 440
• Fits both small‑block and big‑block Mopar V‑8 platforms
• Intended model years: 1957–1980
• Direct‑fit design reduces the need for modification

How is the BIGLKNM housing constructed and what are the benefits?

This thermostat neck is CNC‑machined from billet aluminum for consistent wall thickness and a smooth mating surface. Aluminum resists rust and offers improved heat dissipation compared with many older cast housings, while the polished finish resists corrosion and looks period‑correct under the hood.

• Billet aluminum for strength and even cooling
• Smooth sealing surface to improve gasket life
• Corrosion resistance extends service intervals
• Attractive finish for restored engine bays

What comes in the kit and what tools do I need to install it?

The package contains everything required to replace the housing: the billet thermostat neck, a non‑asbestos gasket, and two stainless steel screws. Installation is a basic engine‑bay job; typical tools include a ratchet set, torque wrench, gasket scraper, and coolant catch pan.

• Included: billet housing, non‑asbestos gasket, 2 stainless screws
• Recommended tools: ratchet, torque wrench, gasket scraper, coolant pan
• Expect to drain some coolant, then refill and bleed system after install
• Check torque specs for your engine when tightening screws

Will this change thermostat size or require other parts?

The BIGLKNM neck is intended as a direct replacement and does not alter thermostat bore dimensions or hose connection geometry for compatible engines. In most cases you can reuse the original thermostat and upper radiator hose, but inspect rubber parts and the thermostat for wear and replace if necessary.

• Thermostat bore matches original equipment fitment
• Upper radiator hose usually remains compatible
• Replace worn hoses or an old thermostat for best results
• Verify hose clamp locations and clearance before finishing

Who is this for: Owners and restorers of classic Mopar V‑8 vehicles seeking a long‑lasting replacement for a worn or damaged thermostat housing. Mechanically inclined DIYers, restoration shops, and performance builders will appreciate the durable billet construction and included hardware that simplify installation and improve under‑hood appearance.