Jumping up top, it was time to remove the spark plug wires, coil packs, and the crossover fuel line to gain access to the valve covers. With the covers removed, Joe pulled the factory rocker arms off of the cylinder heads, then pulled the stock pushrods out of the engine.
Next, the intake manifold was removed, along with the fuel rails and injectors. There is a large vacuum hose behind the intake manifold; make sure you disconnect it from your brake booster before pulling up, or you'll find yourself stuck on the way out.
Unlike a "typical" LS3 cam swap, the VVT camshaft system requires builders to remove the factory Active Fuel Management (AFM) lifters. These lifters just can't handle the lift of an aggressive camshaft, and must be swapped for a set of Comp Cams supplied hydraulic roller units. This means the cylinder heads have to come off.
Pulling the L99 cylinder heads is an easy job for the crew at Vengeance Racing, but it can certainly be a little intimidating for a DIY garage job. With the long-tube headers removed, Joe unbolted the cylinder heads and pulled them off of the engine.
Next, the oil pump was removed, which requires unbolting the oil pump pickup tube from the pump prior to removal. The pickup tube bolt is easily the most frustrating bolt to access on the LS engine and, if you're not careful, can easily end up in the oil pan. Take your time, work slowly, and don't drop the bolt!
A single bolt holds the VVT timing gear to the camshaft. Once removed, the timing gear can be pulled off the end of the camshaft by hand. Note that the factory timing chain tensioner must be relieved prior to removal, which can be done by holding the tensioner to the side with a small pin.
Finally, it was time to pull the camshaft out of the L99. If anything, this is the point of no return, but if you've made it this far, you're half way there. Joe takes care to remove the factory camshaft slowly to ensure he doesn't scratch or gouge any cam bearings on the way out. Then the new Comp unit is coated in Royal Purple and slid in place.
Remember that Comp Cams phaser limiter kit? Well, it was time to modify the factory VVT timing set to limit the camshaft phaser's motion. In stock form, the VVT phaser is capable of advancing or retarding the camshaft by 52 degrees. The Comp Cams kit limits that swing to 22-degrees, "providing the necessary valve clearance for more aggressive hydraulic roller camshafts with tighter lobe separations, all while still reaping the benefits of GM VVT technology."
Comp provides excellent instructions in the phaser kit, which makes installing the limiter a simple task. Using a vice, Joe clamped down the timing gear and utilized the provided tool to rotate and lock the phaser in position. Then, he swung the rear cover out of the way, installed the limiter, and reassembled the timing set.
Installing the modified VVT timing gear is as easy as dropping it back in place and bolting it down. Joe lined the camshaft up dot-to-dot and tightened everything down to spec. At this point, you can put the oil pump back in place, tighten down the pickup tube, and reinstall the front timing cover.
Removal of the factory AFM lifters requires replacing the stock L99 valley cover with an LS3 unit, which is as easy as bolting the new LS3 cover in place. The L99 cover (top) controls oil flow to the stock AFM lifters and, with those lifters removed, can cause a low oil pressure situation. The LS3 unit covers the factory oil galley and keeps everything working harmoniously.
The new 0.566/0.578-inch lift camshaft would wreak havoc on the factory valvesprings. Comp recommends switching to a quality single or dual spring with this camshaft. Vengeance Racing installed a set of Comp Cams' dual springs, which include new tool steel retainers, 7-degree valve locks, new seats, and seals. Installation is as simple as pulling the stock springs and dropping the new units in place.
Finally, it was time to slide the new 7.400-inch, one-piece hardened pushrods into the cylinder heads, then get to work on reassembling the top half of the engine. The factory rocker arms bolt back in place, then the valve covers, coils, plugs, wires, headers, intake manifold, and remaining components can go back where they belong. After that, it was off to the dyno …
With Mike Carnahan of Vengeance PCM behind the laptop, a new tune file was loaded into the VCM and our test Camaro was run through the paces. The new Comp Cams' VVT camshaft kit laid down 404.39 rwhp and 385.27 lb-ft of torque through the automatic transmission, a gain of 39.02 rwhp and 2.6 lb-ft of torque, even with the VVT phaser limited to 22 degrees.
Looking closer at the dyno graph, it's easy to see just how much more useable power the Comp Cams bumpstick delivers. From 4,500 to almost 6,500, power is up across the board, carrying far past the factory camshaft. On the street or track, this would be noticeable, to say the least. And, best of all, we got to keep the VVT functionality!