It’s no secret that if you’re looking to make big power, GM’s LS engines are an excellent place to start. While these engines are incredibly powerful and durable, they do have a few weak points–many of them in the valvetrain. The search for power means adding bigger cylinder heads, longer duration camshafts with more lift that also demand stronger valve springs. All these improvements also increase the load on the stock LS rocker arm.

As a stock component, the LS rocker arm is a well-engineered piece. Despite its compact size, this investment cast rocker is incredibly strong and uses a roller bearing fulcrum which is a vast improvement over the high-friction ball and stud arrangement of its small-block Chevy predecessor. But with these increased spring loads, the stresses are also greatly increased on the stock fulcrum.

The good news is that several companies make an upgrade kit. Summit Racing has not only produced a kit that increases the strength of the trunnion and bearings, but has created a great little installation tool that makes the conversion very easy. Even stopping to shoot photos along the way, we had a complete set of 16 roller rockers converted in less than an hour.

Here’s how we did it:

assortment of old gm ls rocker arms in a pile
summit racing rocker arm trunnion upgrade kit
summit racing trunnion installation tool kit with numbered parts
pressing a bearing into a trunnion with a bench vise
assembling an ls trunnion prior to install into a rocker
pressing a bearing into an ls trunnion with a bench vise
pressing trunnion into a rocker arm with a bench vise
installing snap rings onto rocker trunnion
tightening down rocker arms on a ls engine

We unbolted a set of very well used LS rocker arms and upgraded them to a much stronger and more durable Summit Racing trunnion kit for much less than the cost of a set of aftermarket rocker arms.

The Summit Racing rocker arm bearing upgrade kit consists of 16 trunnions, 32 caged bearings and heavy duty snap rings that are easily installed in the stock LS rockers.

What makes this job exceptionally easy is the Summit Racing trunnion and bearing install and removal tool. The large fixture (1) sits in the vise, held in place with two small magnets (6). The round tool is called the End Cap (2). The cylindrical tool with the integrated center stop is called the mandrel (3). The alignment sleeve (4) and large washer (5) complete the kit.

To begin, insert the two small magnets into small holes in the fixture and set the fixture in your bench vise. Place the hollow side of the End Cap over one end of the stock rocker arm and tighten the vise to press the old bearings out of the rocker.

Now place the End Cap over the larger end of the mandrel. Place a new roller bearing over the other end of the mandrel followed by the alignment sleeve.

With the alignment sleeve inside one side of rocker, use the vise to press the bearing until it is flush with the side of the rocker.

Place high quality assembly lube on both sets of bearings and slide the new trunnion into the installed bearing and place the large washer over a second bearing while using the trunnion to center the bearing and washer. The trunnion should remain free to rotate while you press the second bearing into place with the vise.

With both bearings pressed into the rocker body, the trunnion should move freely. Install both snap rings onto the trunnion. Summit specs the side-to-side clearance between 0.005 and 0.010-inch.

Parts List

Summit Racing LS Rocker Arm Bearing Kit (SME-143002)
Summit Racing Rocker Trunnion Install Tool (SME-906011)
Summit Racing LS Rocker Bearings (2) (SME-143002-2B)

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Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.