The GEN 5 LT1 and LT4 engines are equipped with Variable Valve Timing (VVT) controlled by a cam phaser. A cam phaser is a computer-controlled cam gear that optimizes camshaft timing based on load and engine RPM. Engine oil is fed to the phaser through a computer-controlled solenoid into the control chambers. This technology was introduced on the GEN 4 LS engines then carried onto the GEN 5 and provides several efficiency benefits. However, it does present a challenge when running an aftermarket high-lift camshaft due to the wide range of valve timing movement and constantly changing piston-to-valve clearance. In stock form the cam phaser has 62 degrees of movement. With the installation of the COMP Cams limiter kit movement is reduced to 20 degrees. This will allow the necessary valve clearance for performance camshafts with tighter lobe separations while still utilizing the benefits of VVT technology. The focus of this article is on the specifics of the cam phaser limiter. Installation will vary between each model.

This is the COMP Cams LS & LT Camshaft Phaser Limiter. It includes the necessary installation tools and limiting wedge.

With the tool installed the spring pressure is released from the retaining pin.

The four short retaining bolts are removed so the outside ring can be rotated clockwise. Be sure to Not Remove the long bolt that also acts as the spring clocking pin. This will expose the oil chambers where the limiting wedge will be installed. Here it installed at the 5:30 position.

I discovered while working a 2017 LT1 and 2016 LT4 a difference between the two cam phasers. The front reluctor wheel is slightly different and the LT4 phaser has two narrow coil springs compared to a single wide spring on the LT1. I used two spring tools together to release the pressure on the LT4 cam phaser.



Once the wedge and 4 reluctor bolts are installed the phaser can be bolted up to the camshaft using a New oil-flow control retaining bolt. Note alignment marks between the cam and crank gears.