The concept of a roller lifter that utilizes a bushing or plain bearing, instead of the more traditional needle bearing between the wheel and axle, is hardly new. It’s been available for race engines for at least a couple of decades. And, there have been success stories, including running in the Indy 500 and in NASCAR. However, some engine builders have questions about the viability of bushing lifter in terms of durability, effects of drag, lubrication issues, and, of course, cost.
Isky Cams is eager to change that perception with the release of a series of needle-free solid and hydraulic roller lifters.
Here’s the choice in roller lifters: a bushing style, left, or needle bearing. Both have pros and cons.
“The idea has been around for years,” says Nolan Jamora, director of research and development at Isky Cams. “We decided to do it because [a needle bearing] was always the weak link in the valvetrain after the springs improved.”
The design differences between a bushing — Isky refers to it as a “solid bearing” but we’ll use bushing as it’s a reference more familiar to engine builders today — and needle bearing are simple, but the pros and cons of each aren’t always so obvious. The needle bearing wraps the axle with numerous tiny cylindrical rollers that are well-suited for reducing friction because the line point of contact is so thin along the length of the needle. However, needles can suffer surface wear and flat spots if the loads are too heavy for such a small contact area. With the bushing design, the axle shaft does not touch the bushing shell. Instead, there is a film of oil or hydraulic wedge that carries the load of the lifter. With proper oil pressure and the correct lubricant, the bushing cannot only last longer, but by spreading the load over a greater area of the axle, the lifter can support higher spring pressures.
Jamora recalls seeing a 3-foot-tall industrial roller lifter that used a bushing between the axle and wheel. “But it ran soaked in oil and at a very low RPM, so it worked very well,” he says. “The problem is when you put RPM or a heavy load, the pin would squish oil away from the material and run metal to metal. People have tried to solve that problem and couldn’t.”
[quote align=”alignright” width=”200″]Long story short, we’re trying to provide a bulletproof part for our customer. — Joe Jolly, Sunset Performance Engines[/quote]The key to making bushing work in a roller lifter is not designing a better bushing, says Jamora, but rather finding the right material for the bushing and delivering oil to maintain a film wedge.
“We went through many different materials and two to three years of testing,” explains Jamora. “We developed a material with enough porosity to hold the oil under high-stress conditions, such as high spring pressures and high RPM.”
The material that Isky developed is bronze in color, but that doesn’t reveal much about the metallurgy, which is proprietary.
“It was not only a challenge in finding the right mix of elements but also finding a manufacturing method that brings in all the right ingredients at the right time,” says Jamora. “You can break it down but you won’t understand how it’s put together. It’s a complete mix of different metals. It can’t be defined as steel, bronze, or copper.”
Different views of axles and wheels on .904 and .842 Isky bushing-style lifters.
Numerous metals were tested on a Spintron, including one challenge where the oil pressure was cut off. Development from those exercises led Isky to apply for design patents that help maintain oil in the bushing roller. In addition, computer modeling and testing allowed Isky to determine the proper clearance between the axle and wheel bushing. Isky won’t discuss specifics with regard to the clearances, only to say that there are different clearances for different applications and materials when needed. As development continued, Isky expanded the line to include hydraulic roller lifters as well as more applications, including Harley-Davidson engines. The company also came out with an entry-level version for hot street and high-performance use.
Versions Of EZ-Roll Lifter
The lifters are called EZ-Roll (the EZ stands for extreme zone), with two high-performance models: EZ-RollX and EZ-RollMAX. The entry-level model is EZ-Roll Jr.
“During development we kept getting better, so three versions are now offered,” says Jamora. “First was finding the right material, then getting it to work over different applications and uses, like oval track, drag, marine, and endurance. We ran them in racing for a couple of years before releasing them to the public. They’ve been in Pro Stock, alcohol dragster, and 24 Hours of Daytona.”
Isky also makes a bushing-style lifter for Harley-Davidson Evolution and Twin-cam engines. They’re rated to just over 160 pounds pressure on the seat. Called the EZ-Riders, these lifters feature a slow leak-down body. There’s also a standard leak-down version for the Evo.
The EZ-RollX is designed for naturally aspirated engines with open valvespring pressures up to 1,100 pounds and nitrous-fed engines up to 900 pounds. Current applications include small-block Chevy, including LS and SB2 heads, big-block Chevy, Chrysler R block (48-degree lifter bank angle), Chrysler B engines, Chrysler Hemi, Ford small-block and Ford 429-460 big-block. Various body diameters are offered for many applications. For example, the small-block Chevy can be .842, .903, or .936. Most lifter bodies are constructed from steel in a standard or lightweight design, and a few SBC applications offer an aluminum top. Pushrod offsets are also available, as are tall models for use in select Bow Tie blocks constructed with raised lifter bosses.
The EZ-RollMAX uses a more advanced bearing material and is designed for open spring loads from 1,100 up to 1,400 pounds, including engines with high boost, nitrous, or alcohol. Applications are similar to the EZ-RollX.
The EZ-Roll lifters will cost anywhere from $275 to $425 more than a comparable needle-bearing lifter, but Isky claims the bushing style will last two to three times longer.
Isky also offers a needle-free roller lifter in a keyway design for select applications. Check with an Isky technical representative for more information.
“We used to change lifters on our spread-port engines every 75 to 90 runs,” says Joe Jolly of Sunset Performance Engines in Sherman, Texas, who explains that previous lifter setups were heavily compromised by side loading, even with centered pushrod locations. “Now we’ve doubled that and then some. We had a problem in the beginning because we were running too much spring pressure for the EZ-X, then we went to the EZ-MAX and haven’t looked back since.”
Closeup of the bushing.
Saving The Engine
One of the best selling points for the bushing-style lifter is saving parts if there is a lifter failure. Should the needles shatter, then pieces can get into the oiling system and damage other parts.
“There’s no shrapnel going through the engine to get hung up on the piston skirts,” says Jolly.
“You may scuff the camshaft, at worse, if an EZ-Roll lifter fails,” echoes Jamora, adding that the lifters can usually be rebuilt. “The lifter will stay together, and you won’t put needles through the engine.”
Isky tested various alloys before developing a bearing material that would maintain a consistent oil film between the axle and wheel. Even the clearances are proprietary for the different lifters.
Some engine builders may express concerns over increased drag with the bushing lifter when compared to the needle bearing.
“We personally didn’t see any gains there,” says Jolly. “Long story short, we’re trying to provide a bullet-proof part for our customer.”
Jamora says the EZ-Roll lifters include a special break-in fluid, and some users may see an increase in parasitic drag during that brief break-in period. “But once it gets rolling, [drag] is actually less over time than with the needle,” says Jamora. “Also, as needles break in they start to wear. Those scuff marks will lead more drag than a bushing would ever have.”
Isky offers the EZ-RollX, left, and EZ-RollMax to suit the different needs of engine builders.
The EZ-Roll Jr. line of bushing lifters targets normally aspirated small- and big-block Chevy engines that don’t use valve springs rated higher than 700 pounds open. Available only with a .8415-inch diameter and .750-inch wheel, these lifters come with a center pushrod seat location and standard seat height. The tall tie-bar will work with both standard and raised lifter boss cylinder blocks. The street price for a set is just over $800.
Keeping The Oil
A key design feature for the EZ-Roll lifters is patented method of delivering oil to the bushing roller. Manufacturers of other bushing-style lifters usually stress that oil restrictors are not to be used with their lifters to avoid any possibility of starving the metal surfaces of the necessary film oil between them. Isky, however, says its lifters are “oil-restrictor friendly” for those engine builders who require finer control of oil pressure and volume throughout the engine.
The patented body design features a 3-point oiling system for proper lubrication.
Isky’s EZ-Roll Hydro lifters leverage the same needle-free benefits into a hydraulic roller lifter. Partnering with Johnson Lifters of Taylor, Michigan, these lifters feature a precision body that is ISO9001 certified.
“That’s the big difference with hydraulic roller failures,” says Jamora. “Often, the machining of the bodies is not very accurate and that can lead to lifters bleeding down and not holding their pressure. With our lifters you can run more RPM and spring pressure than you could before.”
The EZ-Roll Hydro lifters are available for Chevy small-block, big-block and LS engines. Two versions are offered — one rated at 400 pounds open spring pressure, and the other rated at 535 pounds.
The choice between bushing-style and needle-bearing roller lifters boils down to a cost versus increased durability debate. Roller lifters aren’t cheap to begin with, and they can fail, regardless of the design. But needle bearings can’t offer the same insurance policy against widespread engine damage following a failure.
Common sense and basic engine-building standards will increase the life of any lifter. Make sure there’s free movement in the lifter bore, but avoid excessive clearance that can result in sloppy operation. Measure all bores and lifters before assembly, not only to check for size but also any taper or out of round. A typical strategy suggests .0015- to .0017-inch clearance between lifter and bore in an iron block. Because of its higher rate of expansion under heat, aluminum blocks should be tighter in the .0011- to .0013-inch range. Some applications my differ, so always check with the manufacturer.
Proper precautions, such as honing the lifter bores to ensure proper clearance for each lifter, will help extend lifter lift, regardless of style. Changes in valve lash are also a good indication that a lifter may need replacement to avoid failure.
How do you know if a lifter is going bad? “Your lash will start changing,” warns Jolly.
Experts say if needle-bearing lifter gains as little as .0015-inch additional clearance between the needles and axle, it could signal failure. The bushing-style lifter has much more latitude, allowing up to .003-inch before warning flags go up. Finally, special oil is not required to run Isky’s bushing-style lifters. In its simplest form, it’s an R&R upgrade for engine builders. “Basically, whatever you’re doing now, they’ll drop right in,” says Jamora.
The EZ-Roll lifters are available for numerous popular V8 applications.