Moroso Performance Products has been in the game since 1968, essentially growing up alongside the legendary Rat Motor. While the engine architecture is over 60 years old, the demand for better, stronger components hasn’t slowed down. At PRI 2025, Moroso rolled out some new big-block Chevy parts that prove there is still room for innovation on the classic platform, specifically targeting durability and ease of maintenance for street/strip enthusiasts and racers who tear down engines often.
The headline item for the top end is Moroso’s new fabricated aluminum valve covers (P/N 68367). While fabricated covers are common, the details here are what matter. Moroso sized these at 3-inches tall, which is a sweet spot — it provides enough clearance for Jesel-style shaft rockers, but stays low enough to avoid interference on most chassis. The smartest feature, however, is the rail design.
They have a 0.375-inch billet rail with pressed-in steel inserts. If you are checking lash frequently, those inserts are a lifesaver; they stop the fasteners from galling or chewing up the aluminum rail during constant removal and installation. Moroso also machined the interior wall flush with the rail. Anyone who has pulled a valve cover and instantly dumped a hidden trough of oil onto hot headers will appreciate that design choice. They come finished in black anodizing with -12AN breather and fill fittings integrated, ready for factory or aftermarket bolt patterns.
For the bottom end, it introduced a new billet high-volume oil pump (P/N 22172). High-flow pumps are great for cooling, but they can suffer from cavitation and housing failure if not built right. Moroso machined this new housing from solid 6061-T6 aluminum and, crucially, tripled the size of the mounting boss.
That extra material prevents the pump from shearing off the block under high stress, a catastrophic failure mode. It is engineered to clear a massive 4.75-inch stroke with steel rods and works with its 10-inch deep pans. They also enlarged the inlet to smooth out flow and reduce cavitation risk.
After six decades, Moroso is still finding ways to make the Rat more reliable. These new big-block Chevy parts blend the clean look builders want with the hardcore street function a race engine demands.
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