Here's a sentence nobody bought a $70,000 2019+ Ram Cummins to hear: there's a known cam-and-tappet wear issue lurking inside your brand-new engine, and ignoring it can end the same way every diesel disaster ends — metal in the oil, a wallet on fire, and a truck on a flatbed. The good news? Hamilton Cams built the fix the diesel world has been waiting for, and it's the kind of upgrade that pays for itself the first time it saves your bottom end.

Hamilton has been the gold standard in Cummins valvetrain for two decades. They build the cams that big-power 5.9s run, the lifters that keep stock trucks alive, and — most importantly for 5th-gen owners — the conversion kit that puts an end to the late-model 6.7 tappet trouble before it gets started. Here's what's going on inside your engine and how the Hamilton Cams lineup at DNR Customs solves it.

What's actually wrong with the 6.7 Cummins valvetrain

Late-model 2019+ Ram Cummins trucks have shown a recurring pattern: premature wear between the camshaft and the lifters (tappets). The wear shows up across a range of owners, mileages, and use cases — stock daily drivers, modified trucks, work trucks. The symptoms usually start subtle and get expensive fast:

• A light tapping or knock from the top end, especially on cold start
• Metal in the oil filter or on the magnetic drain plug
• Bottom-end and valvetrain noise that wasn't there before
• Eventually, lifter and cam-lobe damage that takes the engine out of service

The root cause is a combination of metallurgy, geometry, and operating conditions that's hard for an owner to influence. You can run the cleanest oil on the planet on the strictest interval, and the issue can still show up. That's exactly why Hamilton stepped in.

Hamilton's fix: the flat-tappet conversion kit

Hamilton Cams' flat-tappet conversion kit for the 2019+ 6.7 Cummins replaces the at-risk factory cam-and-lifter setup with an upgraded camshaft and a set of tougher flat-tappet lifters proven on the Cummins platform for decades. It's a comprehensive package — not a single replacement part — designed to give the late-model trucks the kind of durability the older 5.9s have famously enjoyed.

The kit includes:

• A Hamilton-built camshaft sized for the 6.7 application
• Hamilton's hardened flat-tappet lifters
• Supporting hardware to convert the engine cleanly

The net result: a 6.7 Cummins valvetrain that doesn't have the failure point of the OE setup, plus all the quality, fitment, and longevity Hamilton's reputation is built on. Browse the kit in the Hamilton Cams collection; if you'd rather have us install it, request a quote.

Why "flat-tappet" is actually a good thing here

"Flat-tappet" sounds like old technology — and it is older technology than the late-model OE setup — but in the Cummins world, that's a feature, not a bug. Decades of 5.9 12-valve and 24-valve owners have racked up hundreds of thousands of trouble-free miles on flat-tappet valvetrains. The geometry works, the materials are well-understood, and when built right, the wear behavior is excellent.

What Hamilton's done with this conversion is essentially bring the proven durability of older Cummins valvetrains into the late-model platform — same engine, much better long-term odds. It's not a "step backward" — it's a step toward the most reliable setup Cummins ever ran.

The Hamilton cam lineup: more than just the conversion

While we're here, the Hamilton Cams collection is bigger than the conversion kit. Hamilton has been building Cummins valvetrain components since long before the 6.7 existed, and they've earned a reputation as the cam company for serious Cummins owners. Some highlights:

Hamilton performance camshafts

From the legendary 188/220 street cam on up, Hamilton makes performance-ground cams for the 5.9 and 6.7 that wake up the engine without making it a pig to drive. The 188/220 is one of the most recommended street cams in the entire Cummins world — drivable, makes great power, durable.

Hamilton pushrods

If you're chasing power and turning RPM, factory pushrods are a known weak link. Hamilton's pushrods are the go-to fix for built trucks.

Hamilton valve springs and retainers

For built engines that need to control the valves at higher RPM and pressure, Hamilton's springs are the standard.

Hamilton tappets / lifters

The hardened lifters that go into the conversion kit are also sold separately and are widely used as upgrade replacements on any Cummins.

Who should run the Hamilton flat-tappet conversion?

The short answer: most 2019+ 6.7 Cummins owners who plan to keep the truck long-term.

The longer answer:

• You drive your truck and you intend to keep it. If you bought the truck to put 200k+ miles on, this is the cheapest insurance you can run.
• You've started hearing top-end noise. Don't wait for the metal-in-the-oil chapter; act on the symptoms early.
• You're already going in for major work. Pulling the front cover for any reason? Adding a cam, a pump, or doing a head job? Do this at the same time and save the labor down the road.
• You tow heavy or work the truck hard. The stresses that wear out the OE setup show up sooner on a working truck.

If you're sitting on a stock-tune 5th-gen with low miles, you might not need it tomorrow — but it's on the medium-term list. Need a sanity check on whether your truck is showing symptoms? Send us a description of what you're seeing and we'll give you a straight answer.

What about the 12-valve and 24-valve crowd?

For the 5.9 12-valve and 24-valve owners reading this — first, congratulations, you've got the engine the late-model owners are jealous of. Second, the Hamilton catalog is even better-suited to you. The 188/220 street cam, the steel-billet performance cams, the pushrods, the springs — these are the parts that turn a 5.9 from a fun truck into a snappy, reliable, power-making truck without sacrificing drivability.

Whether you're working through our 6.7 Cummins first 5 upgrades guide or planning a big 5.9 build, browse the Cummins performance products alongside the Hamilton collection to round it out.

Install: this is real engine work

Let's be honest about the install: the flat-tappet conversion requires significant front-end disassembly to get the cam out and the new one in. It's not a Saturday-morning job, and it's not the right project for a first-time wrencher. The high points:

• Drain the cooling system, remove the fan, fan shroud, and accessory drives.
• Pull the harmonic balancer and front timing cover.
• Disassemble the valvetrain to remove the lifters.
• Remove the cam, install the new Hamilton cam and lifters.
• Reassemble in reverse, time the engine carefully, refill fluids, prime, and do a proper break-in.

If you have a friend who's done a Cummins front cover before and the right tools, you can absolutely do this. If you'd rather have it done right by techs who've installed dozens of them, drop it off. We'll bundle it with any other work the engine needs while we're in there.

Pairing the conversion with the rest of the right build

Anytime you're doing engine internals, it's the right moment to look at the rest of the build. The high-value pairings for 5th-gen Cummins owners running the Hamilton conversion:

• S&S Diesel CP4 disaster prevention — the 2019+ Cummins has a CP4 hanging on it; protect it. See our CP4 disaster prevention guide.
• FASS lift pump — feed the high-pressure pump and your new internals the clean fuel they deserve. See the FASS guide.
• S&B cold air intake — better airflow, better filtration, better sound. See the S&B intake guide.
• Fleece Cheetah turbo — the right turbo to anchor a built 6.7. See the Fleece Cheetah guide.
• Quality tune sized to your goals.

If you're scoping a full 5th-gen build, our first 5 upgrades guide lays out the right order.

How to tell if your cam is already wearing

The 5th-gen Cummins cam-and-tappet story doesn't usually announce itself with a check-engine light. It starts subtly and gets progressively worse. The earliest signs:

• A light, intermittent ticking from the top end — especially on cold start, especially in the first 10 seconds before oil pressure builds.
• Tiny metallic flecks on the magnetic oil drain plug at oil-change interval. A fresh magnetic plug should look clean; if you're catching glitter, something is wearing.
• Fine metal in the oil filter media when you cut a used filter open and inspect it.
• A vague "the truck doesn't feel quite right" that owners often dismiss before the bigger noises start.

If you catch any of that, don't keep driving and hoping. Get an oil sample, inspect the filter media, and either start planning the conversion or — if you're already symptomatic — get the truck on a lift. Acting early is the difference between a planned conversion and an unplanned engine rebuild.

Oil, additives, and the things that actually help

While we're on the subject of valvetrain longevity: oil matters more on these trucks than the marketing makes it sound. A few rules of thumb that apply whether you've done the conversion or not:

• Run the oil the manual calls for, at the interval it specifies, with a real filter. Don't experiment on a $70,000 truck.
• Heavy duty diesel-rated oils with high ZDDP / anti-wear packages are particularly friendly to flat-tappet valvetrains.
• Don't stretch intervals. 7,500 miles is not the same as 15,000 even if the dashboard says it's fine.
• Inspect every drain. Cut the filter, look at the drain plug, sniff the oil. You'll learn more about your engine than any manual will tell you.

An oil routine on its own won't save a cam that's already started wearing — but it's part of giving any new valvetrain (factory or Hamilton) the best shot.

Why Hamilton specifically — and not just any cam

There are a small number of companies in the diesel space that have been doing what they do long enough that you can buy their stuff with your eyes closed and know it'll be right. Hamilton is one of them. A few reasons we keep recommending Hamilton parts:

• They've been at this for decades. The 188/220 has been a benchmark Cummins street cam for as long as most of us have owned diesels.
• Their materials and machining are excellent. Cam profiles ground on hardened blanks, tight tolerances, consistent unit-to-unit.
• They've built their flat-tappet hardware to take real abuse. The lifters in the conversion kit are not "Cummins-shaped lifters from a catalog" — they're engineered for the application.
• They support what they sell. Tech support, fitment questions, install guidance — the difference between a parts company and a real shop.

You can pick any cam company you want. We pick Hamilton because the trucks that come back to us with hundreds of thousands of hard miles have Hamilton parts in them.

Frequently asked questions

What is the 2019 Cummins tappet conversion?

It's an upgraded cam-and-lifter package — most famously offered by Hamilton Cams — that replaces the wear-prone factory valvetrain on 2019+ 6.7 Cummins engines with proven flat-tappet hardware. It addresses the known cam-and-tappet wear pattern these trucks have exhibited.

What's wrong with the stock 6.7 Cummins cam?

The factory cam-and-lifter setup on late-model 6.7 Cummins has shown a recurring premature wear pattern — across stock and modified trucks. The Hamilton conversion fixes the underlying durability problem rather than waiting for the failure.

How long will a stock 6.7 Cummins cam last?

It varies wildly — some owners go many miles trouble-free, others see issues early. The unpredictability is exactly why the conversion is so popular: you're not gambling with the bottom end.

What is the Hamilton 188/220 cam?

One of the most popular street performance cams in the Cummins world. The 188/220 designation refers to its lift/duration spec. It makes excellent power, retains drivability, and has earned its reputation across decades of 5.9 builds.

Can I install the Hamilton flat-tappet conversion myself?

If you've done a Cummins front-cover job before and have the tools and patience, yes. If not, this is exactly the kind of project where a certified diesel shop saves you a lot of trouble. Get a quote and we'll handle it.

Will the conversion change how my truck drives?

The flat-tappet conversion is engineered to deliver OE-style drivability with much better long-term durability. You shouldn't notice a change in daily driving — just peace of mind every time you start it.

What other Hamilton parts should I pair with the conversion?

If you're chasing power on the 5.9 or 6.7, Hamilton's pushrods and valve springs are the natural next step. Browse the full Hamilton collection for the lineup.

Is the Hamilton conversion better than a stock cam replacement?

Yes — and meaningfully so. A stock cam replacement gets you back to the original failure-prone setup with new parts. The Hamilton conversion gets you off the problematic geometry entirely and onto proven flat-tappet hardware. If you're going to do the labor, do it once and do it right.

What is the 188/220 cam good for?

It's a street-friendly performance cam that wakes up a Cummins without making it a pig to drive. Excellent power per dollar, drivable on the daily, and durable enough to live in a tow rig. One of the most-recommended Cummins street cams of all time.

Does the Hamilton conversion affect emissions equipment?

It's an internal engine modification, not an emissions modification — the cam-and-tappet swap doesn't change your DPF, EGR, or DEF systems. As with any engine work on a late-model truck, follow local laws and check with your shop about applicable regs in your area.

Stop guessing — start protecting

If you own a 2019+ 6.7 Cummins, the Hamilton flat-tappet conversion isn't a "maybe someday" mod — it's an insurance policy you'd rather have before the cam tells you it's been wearing for the last 50,000 miles. The hardware is proven, the install is well-documented, and the math is in your favor every way you look at it.

And if you're on a 5.9 or older 6.7, the rest of the Hamilton lineup — cams, pushrods, springs, lifters — is the kind of valvetrain hardware that turns a fun truck into a fast truck without compromising the daily-driver story. Browse the full Hamilton Cams lineup, pair it with the rest of your Cummins build, and when you're ready to put it together, send us a quote request and we'll do it right.

Stop guessing whether your cam is fine

The 2019+ Cummins cam-and-tappet story is the kind of issue that goes from "no big deal" to "rebuild" without much warning in between. Hamilton built the fix, the diesel world has rallied around it, and the math is simple: a conversion now, or a much bigger bill later.

Shop the full Hamilton Cams collection at DNR Customs, round out the build with the rest of the Cummins performance products, and if you want a human to confirm the right Hamilton parts for your truck — and handle the install — request a quote. We'll get you in the right cam the first time, every time.