2019-2024 Ram 6.7L Cummins Valve Train Parts

The valve train on the 2019-2024 RAM 6.7L Cummins

For 2019, hydraulic roller lifters went into the 6.7L Cummins, a first for any Cummins. They ride on a hollow billet-steel camshaft in the block and work non-adjustable rocker arms, with stiffer valve springs and new exhaust valves up top. The upside is maintenance: there is no 150,000-mile valve-lash service on this engine. The downside is the lifter itself, which became the generation's main internal failure.

What fails and why

The factory lifters have no needle bearings, run tight tolerances with undersized oil passages, and use a pressed steel alignment dowel that can back out. When a roller collapses or seizes, it gouges the cam and sends metal through the oil. The signs are a typewriter-like tick on cold start that does not fade, metal in the oil and a misfire. It hits both standard and high output engines across 2019-2024. Some have failed inside the first 10,000 miles, and an engine past 100,000 miles without noise is considered high mileage for this design. Oil grade plays into it: a Ram TSB rules out 15W-40 on these engines because the thicker oil fails to pressurize the lifters when cold. Out of warranty, the dealer answer is a replacement engine.

Stock replacement vs. upgrade

The aftermarket answers the lifter problem two ways. Solid-lifter conversions use lifter spacers, new pushrods and adjustable rockers to remove the hydraulic section of the factory lifter. Flat-tappet conversions go further: the Hamilton Cams kit uses DLC tappets, a new 178/208 camshaft and adjustable rockers. The Hamilton kit is the conversion in this collection. It changes the camshaft, and no CARB EO is documented for either type of conversion, so check your local requirements before you buy. On the stock side, you will find MAHLE valve stem seals and the genuine Cummins rocker box gasket. For owners building the top end, XDP adds HD high-boost valve springs, performance springs and retainers, billet valve bridges, an HD rocker arm trunnion set and street performance pushrods made for 2019-2024.

What we carry

• Hamilton Cams: 07-cc-24v19+ flat tappet conversion for the 2019-2024 6.7L Cummins.
• XDP: XD390 HD high boost valve spring set, XD313 performance valve springs and retainer set, XD318 HD billet rocker arm valve bridge set, XD319 HD rocker arm trunnion set with polishing tool, and XD399 street performance 3/8-inch pushrods for 2019-2024.
• MAHLE: SS45962 valve stem seal kit.
• Cummins: 3963379 genuine rocker box gasket.

Fitment notes

The Hamilton conversion and the XD399 pushrods are made for 2019-2024. The XDP springs, trunnions and valve bridges are listed for 1998.5-2024, but the 2019 engine moved to hydraulic lifters and non-adjustable rockers, so call us to confirm how they pair with your setup, stock or converted. Know whether your engine is standard output (sales code ETL) or high output (ETM), and check the build sheet rather than a VIN digit. Lifter work can be done in the frame, but it takes magnets to hold the lifters up while the cam comes out and a trough in the cam tunnel, and if a lifter drops, the oil pan has to come off. These parts should not be assumed to fit a 2025 engine. Verify by VIN or use the fitment checker.

Frequently asked questions

What does a failing lifter sound like on a 2019-2024 6.7L Cummins?

A typewriter-like tick on a cold start that does not fade as the engine warms up. Other signs are metal in the oil and a misfire. Oil analysis 500 to 1,000 miles before each oil change is the recommended way to catch lifter metal early.

What does the Hamilton flat-tappet conversion change?

It replaces the factory hydraulic roller setup with DLC tappets, a new 178/208 camshaft and adjustable rockers. Because it includes a cam, plan it as a full top-end and cam job, and no CARB EO is documented for it. Talk to us about parts and installation before you commit.

Can the lifters be replaced without pulling the engine?

Yes, in the frame, but it takes the right tools. Magnets hold the lifters up while the cam is pulled, and a trough goes in the cam tunnel. If a lifter drops, the oil pan comes off, so have a pan gasket on hand before you start.

Does oil grade really matter for the lifters?

Yes. A Ram TSB says 15W-40 is not to be used in 2019 and newer engines because the thicker oil fails to pressurize the lifters when cold. Run 10W-30 CK-4 above 0 F or 5W-40 full synthetic, and shorten intervals if you tow or idle a lot.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.