Pontiac Lifter Guide - Lifter Lowdown

Rhoads Variable-Duration Lifters
Many manufacturers have sought ways to improve the conventional flat-tappet hydraulic lifter and a few have developed units that vary camshaft valve events with rpm. Such pieces typically boost idle quality and low-speed performance, but it seems those offered by Rhoads Lifters are among the most popular. Here's what the company's Jack Rhoads has to say.

High Performance Pontiac: How long has Rhoads Lifters been producing its unique line of lifters?
Jack Rhoads: Our company began producing variable-duration hydraulic flat-tappet lifters over 30 years ago using a patented design developed by my father, James E. Rhoads.

HPP: How many different lifter sets does your company offer for Pontiacs and what is the cost?
JR: We presently offer two hydraulic flat-tappet variable-duration lifters for the Pontiac V-8. The first is our original Rhoads lifter (PN 9518), which retails for $110. The second is our newest V-Max design (PN 9518X) and starts at $149. The Super Lube option adds $30 to the cost of either

HPP: Can you explain the operational characteristics and benefits of each?
JR: Our original Rhoads lifter operates similarly to a standard hydraulic unit, using the same amount of oil flow, but our design leaks at a much higher rate. This reduces valve lift and duration at low and moderate engine speeds by as much as 0.020 inches and 10 to 15 degrees, respectively. That can increase idle vacuum by as much as 3 inches, improve idle quality and overall fuel economy, and increase low-end torque by as much as 15 percent.

Our V-Max design functions much like our original unit, but is fully adjustable instead and must be set much like a conventional solid. Lash preload can be set between 0.010 and 0.030 inches to reduce the camshaft's overall valve lift and duration, which at maximum leakage can increase idle vacuum by as much as 5 inches and improve low-end torque by 25 percent, when compared to a standard hydraulic unit.

As engine speed increases, there's less time per revolution for either version to leak down and both begin operating conventionally by about 3,500 rpm, restoring maximum valve lift and duration for peak performance. And because our lifters continually leak at high speed, they typically don't pump up as quickly as standard hydraulic units, making either design desirable for high-rpm use.

HPP: Can you detail the Super Lube oiling option?
JR: It's a machined groove in the lifter body that runs its entire length and injects oil onto the contact surfaces of the camshaft lobe and lifter during normal operation to reduce friction and wear. Our testing indicates positive effects on component longevity without any subsequent effect on oil pressure.

HPP: For what types of hobbyist applications are Rhoads lifters popular?
JR: They seem most popular with owners who install a performance camshaft in a street engine, but want to maintain maximum idle quality and low-speed performance. However, they're commonly used in race applications because of their excellent high-rpm capability, too.

HPP: Is there any application for which you'd suggest they not be used?
JR: They seem to have little effect on engine operation when using a mild camshaft such as that found in a low-performance, passenger-car application. Either design would, however, be an excellent choice when running a factory high-performance grind like a Pontiac No. 041 or an aggressive aftermarket unit.

HPP: Can you explain the increased level of engine noise when running Rhoads lifters?
JR: The leakdown rate of our original Rhoads lifter is higher than that of a standard hydraulic unit, which makes it noisier at idle and low speed. It causes an audible "tick" like that associated with a traditional solid-lifter cam. Because our V-Max lifter leaks down at an even greater rate, additional noise is common, if adjusted to the maximum setting. The minimum setting is quieter than our original design.