Over the last few months, COMP Cams has been filming a YouTube video series highlighting LS valve trains; how they work, how to modify them and how to build more power using simple hand tools and basic modifications. The series is aptly titled, “Back to Basics,” and features veteran automotive writer, Richard Holdener, giving us step-by-step tips along the way. So far, we’ve shared, “Back to Basics with Pushrods” and, “Back to Basics with LS Cam Swaps.”
Now, their latest installment talks about LS valvetrain stability and valve float. Working with a truck-based LS-series engine at Westech Performance, Richard is quick to tell us that in order to understand valve float, we must understand how an engine operates – including the math involved. For example, at an engine idle speed of 600 RPM, the valve is opening five times per second. If your engine is turning at 6,000 RPM, that’s fifty times per second. This includes opening the valves, activating the lifters, the pushrods and the rocker arms.
As Richard tells us, “To better understand valve float, we have to understand which components are involved, such as the camshaft, lifters, pushrods and the rocker arms. GM spent a lot of time and money to ensure that the spring rate and the frequency of the valve spring was optimized for the rest of the valve train components. Any time you change those components, you throw that delicate balance off.” Those changes might include a high-performance camshaft or adding boost, like with a turbocharger or supercharger.”
To prove his theory, he straps the aforementioned LS down to Westech’s in-house SuperFlow engine dyno for a baseline run. Then, he installs a set of COMP 1.72 roller rockers, followed by a valve spring upgrade, showing the changes in horsepower in both peak, and throughout the powerband with each modification.
We don’t want to spoil any surprises by telling you how things turned out, but if you have a few minutes to watch the video and want to pick up a few more tips on understanding valve float, it’s definitely worth the viewing. Until next time!
Rick Seitz is the owner and founder of GMEFI Magazine, and has a true love and passion for all vehicles. When he isn’t tuning, testing, or competing with the brand’s current crop of project vehicles, he’s busy tinkering and planning the next modifications for his own cars.