Late-model engines have spoiled us. The LS-series engines are so well engineered that many car crafters consider them indestructible, which isn't exactly the case. But there is something to be said for such nice valvetrain pieces as those investment-cast, steel 1.7:1 roller rocker arms that come stock on every LS engine ever built. Compare these with those flimsy stamped rocker arms that came stock in a small-block Chevy, and you can begin to understand how some people believe the LS valvetrain is beyond reproach. But car crafters are known for pushing the envelope, and when you get into the 6,500-rpm-and-higher range, the weak points of production engines begin to surface. One way to make some improvements for little money is by replacing the non-caged needle bearings and adding durability with this simple kit offered by Comp Cams. The Comp kit comes with an 8620 steel trunion that supports a pair of caged needle bearings retained by a pair of hefty snap rings. A common affliction is for the stock needle bearings to fall out, which causes all kinds of havoc when they work themselves into places in the engine where they don't belong.
Besides the fact that the kit costs much less than a new set of roller rockers, the conversion process is relatively easy. We borrowed a small arbor press from our machinist friend, Lucki Candoff, and spent a couple of hours removing the old bearings and installing the new ones. A company called CHE Precision makes an outstanding proprietary bushing insert that replaces the needle bearings and offers even more reliability, but you must send your rockers to the company for the conversion, and the price is substantially higher.
While we're on the subject of improving power and reliability, it's a wise move to also upgrade the valvesprings and pushrods. The Comp 26918 beehive spring is an excellent upgrade for any serious street LS engine, especially when combined with a stronger, thick-wall pushrod. Comp has created an LS engine valvetrain upgrade kit that includes these two components in addition to a titanium retainer kit that further reduces valvetrain weight. This kit gets a little pricey at just under $530, but you can basically achieve the same goal with just the pushrods and valvesprings.
|Comp LS trunion retro-fit kit||13702-KIT||Summit Racing||$134.95 |
|Comp LS beehive valvespring||26918||Summit Racing||$205.95 |
|Comp LS Hi-Tech pushrods||7955-16||Summit Racing||$134.95 |
|Comp LS valvetrain upgrade kit||54100||Summit Racing||$529.95 |
|Summit LS rocker bearing tool||90601||Summit Racing||$39.95 |
|Lingenfelter HD rocker stands||L200145297||Lingenfelte||$198.96 |
The stock LS 1.7:1 roller rocker arm is an exceptionally designed stock rocker. But when you get into higher engine speeds, it needs some help. Comp has created an LS retro-fit trunion kit that adds this stronger 8620 steel trunion and caged bearings. The kit also comes with replacement bolts.
To convert the stock rockers, merely press out the old bearings and trunion and press in the new ones. We used a simple hand press, but we later discovered a bearing tool from Summit that does the job with a bench vise.
The final step is installing the snap rings on both sides of the shaft to retain the bearings. If this looks simple, it's because it is.
Here's a comparison of the stock rocker on the left and the new and improved Comp conversion rocker on the right.
If you want additional durability and strength, a set of Comp beehive springs and 0.080-inch wall pushrods are great investments if you intend to spin your motor above 6,000 rpm to make power.
The Comp trunion conversion can also be completed on L92 and LS3 offset intake rockers. The real differences between LS3 and L92 valves are the weight and the price, as LS3 valves are hollow stem while the L92 truck engine valves are solid stem. Heavier valves will more likely call for a stronger spring that puts more load on the rocker arm.
The Comp system comes complete with stronger bolts to complete the installation. If you really want to go all the way, Lingenfelter Performance Engineering sells steel rocker seats to replace the EO aluminum set.
3406 Democrat Road
Lingenfelter Performance Engineering