Valvetrain Innovation For The Masses

Priced at $695, Jesel’s new Sportsman Series shaft-mount rocker-arm systems bring trick race technology down to an affordable “regular guy” level.

The Jesel shaft-mount stands bolt directly to the head using the rocker-stud bolt holes. The stands are designed for universal fit on most popular cylinder heads with conventional valve layout. We installed this set on Air Flow Research heads; we tried to mount them on a set of Brodix heads, but they were about 1/8-inch too short so they would require shimming. Jesel sells a stand height checker that can be used to determine the proper shim thickness required to set up the stands.

Eight special head bolts (four for each side) are included that can be swapped for the top row of head bolts if the rocker stands interfere with the stock bolts. We found that the Jesel stands easily cleared the ARP six-point head bolts we already had on our engine. However, if you have studs (as shown here), you’ll definitely need the special bolts, and you may have to pull the heads off to remove them. Torque the replacement bolts to the same spec as the stock ones.

Jesel supplies both T45 and T50 Torx-head sockets with the kit so you don’t have to go in search of them at Sears.

Shorter pushrods are necessary with the Jesel system, and the company packages a pushrod length checker with each kit to make this easy. Both the intake and exhaust pushrod lengths should be checked because the base circles may be different. Make sure to account for lash with a solid-lifter cam by inserting the appropriate feeler gauge between the tip of the rocker and the valve stem, then lengthen the checker to determine the correct pushrod length. On this solid-roller application, we needed pushrods that were about 0.125 inch shorter than the 7.850-inch pushrods we were using. Unlike a stud-mount system where pushrod length is critical to proper geometry, determining correct pushrod length and valvetrain geometry is much easier with the shaft-mount system because the rocker fulcrum’s location is fixed on the shaft. You can’t really “force” a longer or shorter pushrod to work.

Setting valve lash with a solid cam or preload with a hydraulic cam is very simple with the Jesel rockers. Loosen the adjuster, set the lash or preload, and tighten the lock nut. This style of adjuster is far stronger and less likely to loosen or flex than a polylok. You can also remove the rockers and replace them without having to go back and reset the lash, for example, if you’re changing valvesprings or have to pull a head at a race.

Jesel. In the realm of valvetrain components, the name evokes images of Pro Stock and Winston Cup—the cream of the motorsports crop and way out of the street machiner's league and pocketbook, right? Well, maybe not anymore. Known for the quality, variety, and the price of its race-derived shaft-mount rocker arm systems, Jesel has recently introduced a new Sportsman Series of shaft-mount rockers priced under $700 that bring this trick technology down to an affordable “regular guy” level.

What's the difference between these budget kits and the company's higher-end stuff that costs two or three times as much? Not a lot, really. The main difference is that the SS systems are available only for basic stock geometry valvetrains in common applications. In other words, if you need 18-degree offset rockers for a full-wazoo circle track application, you'll still need to step up to one of the higher-priced systems. Jesel's Sportsman rockers also omit some of the bells and whistles of the higher-end systems, like ultralite rocker arms. However, you still get the same CNC-machined billet aluminum rocker arms, steel rocker stands, and Grade 8 hardware used in the rest of Jesel's lineup. Initially, the Sportsman rocker arm systems will be available for standard Chevy small-block 23-degree heads, standard big-block Chevys, standard Ford small-blocks, and GM Gen III small-block LS1/LS6 engines.

So what's all the hoopla about shaft-mount systems anyway? With hydraulic- and solid-roller camshafts becoming increasingly popular on mainstream street/strip engines, the demands on valvetrains have increased as well. Aggressive lobe profiles that slam the valves closed on their seats, combined with generally higher rpm in the case of the solid-roller and the increased weight of the lifters with a hydraulic roller demand greater and greater valvespring pressures to keep the valves from floating. It's not uncommon to see streetable applications with spring pressures as high as 200 pounds or more on the seat and well over 500 pounds at full lift. Pressures like that are virtually beyond the ability of a stud-mount rocker system to endure without flexing to the breaking point; that's where a stud girdle comes in. By tying the row of rockers together, the whole assembly gets more rigid, but adjusting valve lash becomes a nightmare because the girdle has to be loosened and retightened to set each valve properly.

Bolt-down shaft-mount systems, on the other hand, offer several advantages over common stud-mount systems: greater strength and rigidity, more accurate ratios, and easier serviceability. The strength and rigidity advantages stem from the shaft-mount design, which ties each cylinder's pair of rocker arms together on a common shaft, which in turn bolts to a one-piece steel base that mounts directly to the cylinder head. Since the shaft-mounted rocker pair is very rigid, you eliminate the guideplates and rocker arm studs. You can also do away with polyloks and a stud girdle if you were using one. Jesel says the Sportman rockers are good to about 270 pounds of seat pressure and 500-plus pounds open.

If you're building a valvetrain from scratch on a new engine, you'll find that the Sportsman series from Jesel will cost about $200 more than a set of aluminum roller rockers with guideplates, rocker studs, polyloks, and a stud girdle.

When we first learned of these new shaft systems in a press release, we were interested in trying a set simply for the trick-technology-at-a-reasonable-price angle. When the valvetrain in our daily driver grenaded about a week later for no apparent reason, our interest got more personal.