The Colt Camshaft Reliability Kit allows 2019-2024 5th Gen Dodge Ram trucks to upgrade the reliability of their 6.7L Cummins valve train by converting the failure-prone stock hydraulic roller camshaft to the exceptionally reliable flat tappet and cast camshaft combination.
Chilled cast iron camshafts have advantages over steel, especially when used in flat tappet combinations. The semi-porous grain structure of cast iron creates natural voids that hold important oil lubrication. Chilled cast iron produces extremely hard and durable wear surfaces with proven million-mile reliability that started in 1989 B-series 5.9L Cummins engines with continued reliability thru 2018 6.7L Cummins engines. Although high zinc and phosphorus oils with greater than 1,200 ppm ZDDP provide additional boundary layer protection for flat tappet camshafts, chill-hardened cast iron cams and lifters are more tolerant to lower ZDDP oils (i.e. Cummins allows for CJ-4 and CK-4 oil usage in 2018 and older model years). After the initial 20-minute break-in period, Colt Flat Tappet Reliability Kits are compatible with any oil recommended for your Cummins 6.7L engine.
Key Kit Components
1. Choice of Colt Cams Tow Series 181/210 or Street Series 181/218 chilled cast camshaft.
2. Set of (12) Colt 1.4” flat tappet retrofit chilled cast lifters.
3. Set of (12) Colt 7/16” Chromoly Pushrods (6,500 lb buckling strength)
4. Set of (6) 6.7L-style adjustable rocker arm pairs (intake/exhaust) w/pedestals
5. 1oz Tube of Assembly Grease
Optional: Add Power Driven Diesel 15w-40 Conventional Oil for break-in.
During install, enlarged barrel 1.4” retrofit flat tappet lifters are used to replace the OEM hydraulic roller lifters. Take note that Colt retrofit lifters feature a 1.40” foot diameter ensuring proper cam journal clearance for all 2019+ engine blocks. The new Colt flat tappet camshaft is then used to replace the factory stock roller camshaft. New upgraded 7/16” chromoly pushrods with the traditional 10mm ball and cup design replace the factory stock 3/8” failed pushrods. The system is then completed with new early 24v 6.7 Cummins style adjustable rocker arm and pedestal assemblies.
How to Adjust Valve Lash
Colt has separated itself in the world of aftermarket diesel performance camshafts by producing OEM quality camshafts engineered with smooth lobe geometries that provide for quiet valve train and million-mile reliability, exactly what every Cummins is known for. In addition to the (Big Stick) Tow Series 181/210 and Street Series 181/218 camshafts, Colt offers multiple custom-ground upgraded camshaft profiles for owners looking to extract more from their Cummins engine.
Why 2019-2024 6.7 Cummins Fail
2019+ 6.7 Cummins engines come standard with hydraulic roller camshafts with mass manufactured 3/8” ball end pushrods, and non-adjustable rocker arm assemblies. It is common for the hydraulic roller lifters to bleed down when parked overnight leading to noisy valvetrain at startup. This “typewriter tick” gets worse overtime as mileage accrues and the roller lifters take longer to pump up and remove lash in the system. To make matters worse, the traditional cup on the pushrod (that holds oil to prevent dry starts) was replaced with a ball and inverted cup on the rocker arm. The dry start combined with the bleed down typewriter ticking hammers the pushrod ball and rocker cup mating surfaces. Over time, pushrod ball and rocker cup wear introduce heavy abrasive wear metals into the oil system that accelerate wear throughout the whole engine. Left untreated, the pushrods wear enough clearance to jump the cup, bend the pushrod, and the now free-floating roller lifters begin to chatter and fret the camshaft lobes. Some customers report factory roller camshaft failures as early as 20,000 miles with some going through multiple camshafts within the factory warranty period.
Don’t wait for your truck to be sidelined by a failed roller camshaft, fix the problem once and for all with the Colt Flat Tappet Reliability Kit!
*We recommend 0.010” intake valve lash and 0.020” exhaust valve lash, rotating the engine and using the companion cylinder method (cyl1 and 6, 2 and 5, cyl 3 and 4) is the Colt recommended way to set and verify valve lash*
**We recommend high zinc, greater than 1,200 ppm (ZDDP) oil for the initial 20-minute break-in period. Start the engine, hold and slowly vary the RPM between 1,500 and 2,200 RPM for a period of 20 minutes. Camshaft lobes are splash lubricated and elevated RPM along with variable speed will ensure adequate splash lubrication for the critical initial break-in period. High zinc oil during break-in acts like an added insurance policy to ensure your camshaft doesn’t go flat: Power Driven 15w-40, Driven DBR, Motul 10w-40 Break-In, Amsoil SAE30 Break-In, VR1 10w-40 are all examples of high zinc oil. After break-in, change the oil and filter and refill with your choice of engine oil suitable for your Cummins 6.7L engine i.e. CK-4 specification.
***Professional installation recommended. Although a competent DIY mechanic can install this kit, the fastest installation requires lifting the cab of the truck and most DIY mechanics do not have a lift
