Install Guide: Upgrading a 5.3 LS With a Cam Swap
LS Cam Swap
LS engines have huge power potential just waiting to be unlocked. One of the most common upgrades is a cam swap. We’re doing just that on the junkyard LM7 5.3 that we’re planning to use in our ’68 C10 project. The above video shows what a 5.3 cam upgrade looks like and a few things to look out for.
As for the cam itself, we chose a BTR "Truck Norris" cam. These are designed to work well in street-driven 5.3 and 6.0 truck engines. BTR recommends a stall of at least 2400 rpm and the obvious upgrades to the springs and rocker trunnions. Some work to the ECM will also be required. In our case, we chose to start from scratch with a Holley Terminator.
5.3 LS Cam Swap Without Removing Heads
In short, it can be done, but we didn’t do it. Upon inspection after disassembling the valvetrain on our 130,000 mile engine, we discovered some wear on the pushrod tips and rocker arms that was likely caused by failing lifters. We elected to pull the heads and do the job right to rectify the situation. However, if these components on your LS pass a careful inspection, then it’s entirely possible to complete a cam swap without pulling the heads.
Here's where those dowels come in. Sure, we could have just flipped the engine upside down to hold the lifters up, but you can’t really do that if it’s still in the car. So, we elected to show what it looks like to do this right side up. Spin the cam over with the rockers removed and the lifters should stay up, allowing 5/16” dowel rods to be inserted in the oil passages. This holds the lifters and allows the old cam to be removed and the new one installed.
5.3 LS Valve Spring Upgrade
Regardless of whether you pull the heads or not, you’re going to want to upgrade the stock valve springs as well. We used a set of PAC beehives that will allow our LS to take full advantage of the cam and the engine's improved rpm potential. While we were at it, we also replaced the valve seals.
Here’s where another handly tool comes in. A Valve Spring Compressor Tool allows the springs to be compressed while the heads are installed. Don’t forget to fill the cylinder with compressed air to keep the valves from dropping.
5.3 Trunnion Upgrade
5.3’s and many other Gen III engine have issues with the stock rocker trunnions when a running a cam with much more than stock lift. The solution is a trunnion upgrade kit, and Speedway Motors offers one that comes with everything you’ll need, including the tools for install.
Head Removal and Reassembly
As we alluded to, we elected to pull the heads on our engine to replace the lifters. We used our LS7 Lifter Kit (don’t forget to order two sets of 8) and new lifter trays. We also installed a new set of pushrods and a few new rocker arms to replace those that were damaged. While the heads were off, Zach took them over to Speedway Motors Racing Engines and surfaced them. This is recommended any time you pull the heads, and Zach went one step further on ours and lapped in the stock valves. Don’t forget that these engines use torque-to-yield bolts, so a new set of head bolts will be required, along with new head gaskets. Also on the "you don't have to but you should anyway" list is a new timing set as well as a new oil pump.
With everything re-assembled, our engine was buttoned up with new valve covers and the stock intake. Be sure to check out our C10 Build Episode 4 to hear it scream on the dyno. Spoiler alert: we made 430 horsepower!
