Quick Tech: DIY LS Trunion Upgrade With COMP Cams

The LS family of engines has become the most popular powerplant used for performance upgrades, and for good reason: they’re small, cheap, have loads of horsepower potential, are plentiful, and the aftermarket has showered the industry with go-fast parts for them.

If you’re looking to find one of these magical engines in a junkyard you might want to think about upgrading the stock rocker arm trunions before you try and make big horsepower.

The rocker arm trunion is part of the assembly that rotates the rocker arm each time the engine goes through the combustion process. When you upgrade the camshaft in an LS engine, the additional lift and duration will really increase the amount of stress on the stock rocker arm. The problem is that as stress intensifies it will cause the stock cap inside the rocker arm to move and eventually walk out of the rocker arm itself. When that cap moves too much the needle bearings that are inside the rocker arm will fall out and get circulated throughout the engine, causing a lot of problems.

COMP Cams developed its own trunion upgrade kit that addresses the stock trunion problems. The upgraded trunion fits inside the rocker arm and has grooves for c-clips at each end that prevent the walking issue. This not only adds strength to the rock arm, but it also allows it to maintain proper alignment and do its job correctly.

If you think installing this trunion upgrade kit requires the assistance of a machine shop, you better think again. In this video from COMP Cams, you can see just how easy of a project this is to do at home. You just need some basic hand tools and a vice to upgrade the trunions on your LS engine so you can add plenty of horsepower.

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About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. When Brian is not writing, you can find him at the track as a crew chief, doing freelance photography, or beating on his nitrous-fed 2000 Trans Am.
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