PHR Product Test:
COMP's standard hydraulic...
COMP's standard hydraulic roller conversion lifter is on the left. Note how the short-travel piece has been treated with a low-friction coating. The short-travel lifter has about .012-inch plunger travel for higher lift at high rpm versus about .200 inch for the standard piece.
Comp Cams Short-Travel Lifters
In the mid '80s, when hydraulic roller lifters came into widespread use, they offered many advantages over flat-tappet hydraulic and flat-tappet solid lifters. From a wear standpoint, they pretty much lasted forever, and for performance they offered a lot more area under the curve than flat tappets. But even then, the solid roller lifters used in race engines trumped the hydraulic roller in most areas, especially for rpm range, and flat-out power.
Hydraulic lifters employ a plunger that places a buffer of engine oil between the lifting body and the pushrod. As the lifter follows the lobe, the oil takes the place of mechanical clearance, and absorbs the impact of the lobe's ramp, thus reducing valvetrain noise. It also allows friendly tolerances in valvetrain lash for easy installation and low maintenance.
The fly in the ointment is that as the power level increases, hydraulic lifters become increasingly inadequate. Higher valvespring pressure and higher lift keep the protecting oil out of the lifter at high rpm, and the result is too much mechanical clearance, collapsed plungers, and other damaged valvetrain parts. That's exactly what happened to the 469ci big-block in our '68 Chevelle project car. It's partly our fault for letting the oil level get so low, but our stock-style hydraulic roller conversion lifters simply gave up the ghost one night on the highway. We were lucky that our collapsed lifters didn't beat up the rest of the valvetrain or bend any pushrods.
We looked around for a solution, and discovered COMP's new line of short-travel lifters. COMP offers these for most GM engines, including LS, small-block, and big-block Chevys. Without delay, we ordered a set for our big-block (PN 15854-16, $536.95). What makes them unique is that they still offer the hydraulic mechanism with the plunger and oil buffer, but with a much reduced plunger travel. Where most hydraulic lifters have .200-inch of travel, the short-travel COMP piece has just .012 inch of travel. In our case, that would mean high-rpm use would not cause the plunger to collapse, resulting in a loss of almost 200 thou in valve lift. That's equal to a boatload of flow at high rpm. As a hydraulic lifter, we wouldn't need to fuss with setting hot valve lash, and revisiting the operation on a regular basis.
About the only issue we found with the swap is that it requires a .100-inch shorter pushrod when compared to our hydraulic roller conversion lifters we had been using. This is due to the lifter body itself being taller.
When the swap was completed, we noticed a major seat-of-the-pants increase in power. The other thing we observed is that the big-block has a different tune-one that's more like a solid-roller race motor. Gone is the clatter we experienced after running the engine hard (the result of the plungers bleeding off oil and leaving mondo lash). Fortunately, we have a baseline chassis dyno test of the Chevelle with the original conversion kit lifters. This is going to allow us to go back with the short-travel lifters and get a new power curve for comparison. We'll be publishing the whole story soon, so keep an eye out.
First-Gen Torque Arm Suspension
Torque arm suspensions have long proven their effectiveness in third- and fourth-gen Camaros and Firebirds, and are a popular conversion for late-model Mustangs as well. The reason for this is that they work well and they are relatively simple. Total Cost Involved (TCI) has now developed a torque arm system for first-gen Camaros and Firebirds. It was designed to eliminate the suspension bind that occurs when cornering with the conventional leaf-spring suspension. The torque arm features a slider on the front of the arm that slides fore and aft, and rotates as the car goes through suspension travel. This allows the car's handling to be controlled by the coilover shocks and the rear sway bar with no suspension binding. The kit allows for a lower stance, great rear axle control, and dramatically improved handling.
The kit is a bolt-on application except for welding the axle brackets, Panhard bracket, and optional sway bar brackets (which attach to the 3-inch axle housing tubes of a Ford 9-inch housing). Optional TCI Ford 9-inch housings come with all brackets installed and heli-arced.
Total Cost Involved (TCI)
Year One Wheels
As we went to press, we got word from Year One about a brand-new wheel they just came out with. These hoops look like vintage 15-inch steel rally wheels, but they're actually cast-aluminum 17x9s. Currently only offered with a 5-inch backspacing and a 5x4.75-inch bolt circle, Year One is offering a set of four at the introductory price of just $699. (We're told that will eventually settle out around $749.) These wheels have an attractive gunmetal gray powdercoat with a machined outer lip, and look right at home on virtually any '64-80 model GM car or truck. At that price, we can't wait to get our hands on a set of these!
Summit Value Packs
While ordering parts for our most recent engine build-a 400-inch small-block Chevy based on Dart's new series of SHP short-blocks-we discovered that Summit has a new program that groups packages of commonly ordered parts together at a reduced price. These systems are called Value Packs, and they cover a lot of ground. The Value Pack shown is for a mechanical water pump, and includes a Weiand-sourced aluminum water pump, attractive aluminum water pump and crank pulleys, a water neck, pulley bolts, water pump pulley shims, t-stat gasket, and a thermostat. This particular kit is for a small-block Chevy with a short water pump, and costs $215.95.
We checked the Summit website, and discovered lots of other cool Value Packs, ranging from sets of tools (e.g. brakes, ring compressor, and valve lash adjustment), to complete ignition and top end induction systems. In fact, it looks like you could assemble an entire engine from Summit Value Packs if all you had was an engine block. We are actually considering this for a future story. We think it would be really cool to see how inexpensively you could build some serious power using just Summit Value Packs. To see all 99 Summit Value Packs, log on to www.summitracing.com, and search "Value Pack." You won't be disappointed.