Bearings vs. Bushings: The Great Roller Lifter Debate Explored

Bearings vs. Bushings: The Great Roller Lifter Debate Explored

The controversy started quite a few years ago. Mechanical roller cam engines were spitting out roller lifters and killing engines at an unacceptable rate. Everybody had their own ideas on cause-and-effect diagnosis of the problem, along with solutions. For many racers and hot street engine builders, the answer was to convert to a bushing lifter.

While this has become a realistic solution for many engine builders, racers, and street engine builders, it’s not necessarily the universal panacea. Perhaps more importantly, the “solution” brings its own set of issues. Much like a coffee-table-sized jigsaw puzzle, there are multiple interrelated parts to this issue. We’ll cover as many as we can fit into this story.

Identifying the Issues

The first issue that needs to be addressed is understanding what caused all the problems with roller lifters in the first place. While the sources of the problem are numerous, it comes down to a combination of aggressive cam designs coupled with ever-escalating valve spring loads. Toss in loss of valvetrain control and you have the makings for a host of problems to arise. The real damage is done when a roller lifter fails and dozens of those tiny needle bearings escape. This causes catastrophic damage throughout the rotating assembly.

This is an Isky solid roller bushing material that Isky’s Nolan Jamora told us has undergone extensive testing. It continues to be upgraded with routine changes to its composition. Note the pressurized oil feed to the bushing.

As an example, a friend suffered just such a failure in his street/strip 434ci small-block ’55 Chevy. The owner noticed the engine started to squeak about a mile from home but he chose to drive it the remainder of the distance. The noise was the lifter failing which subsequently destroyed the bottom end. The foreign debris put nasty gouge marks on the cylinder walls when the needles wedged between the piston skirt and the cylinder wall. This necessitated a complete rebuild along with, of course, a new cam and lifters.

Failures like this example have motivated engine builders and racers to replace roller lifter bearings with solid, one-piece bearings called bushings. In an interview with Jesel’s Dave Grob, he mentioned that Jesel is still very much in favor of needle bearing roller lifters, although Jesel now offers bushing versions because enough customers have asked for them. Grob says bushings, especially those running with high spring loads, require roughly five more horsepower (depending upon loads and RPM) to spin. This may not be significant in a 2,500-horsepower turbocharged engine but in a naturally aspirated class competition engine, that amount of power is a concern.

Listening to turbo cars on the starting line when they bang, I literally cringe. — Billy Godbold, Comp Cams Valvetrain Engineering Group Manager

Not A One-Size-Fits-All Solution

The advantages offered by bushings are fairly obvious, the largest of which is no minuscule needle-bearing missiles seeking deadly targets inside your engine. However, with bushings comes the same requirement that all the bushing manufacturers that we spoke to pointed to as critical. The racer or engine owner must keep track of the lash. This may seem simplistic, but even competitors with extremely expensive engines often overlook the obvious. During between-round or between-race maintenance, if the lash changes, that indicates something is amiss.

Determining if the valvetrain has been subjected to damage is sometimes difficult to determine unless the driver notices an audible float or severe loss of power. If you have to use a socket and a hammer to knock the locks loose from the valve, that’s a strong indication the system has float. This is a major clue that the valvetrain has suffered separation anxiety, meaning the spring has lost control of the valve.

All the companies that we interviewed reinforced that it’s critical to keep a maintenance record of lash and to note if a given lobe has changed by more than 0.001-inch. If so, this is a warning flag that something in the system is wearing and should be investigated. This brings us to when a racer or street enthusiast should consider converting to bushing lifters. We posed this question to Comp Cams’ Director of Valvetrain Development Billy Godbold.

“If you run an engine with an ignition cut-out where the engine backfires on the starting line, you need a bushing lifter,” says Godbold. “If you run a turbo car with a boost controller where it bangs against the limiter and you hear the engine pop out the exhaust, you must run a bushing lifter. If your valvetrain is out of control, you most definitely need a bushing lifter.”

When building a high-RPM engine, it’s always a good idea to consider increasing the lifter body diameter. A larger wheel such as these Jesel examples (left) reduce wheel speed and are worthwhile for a number of reasons. This Comp Sportsman solid roller lifter (right) is for a standard small-block Chevy with 0.842-inch diameter lifters using a 0.750-inch wheel diameter. A larger diameter lifter such as the Mopar 0.904 diameter lifter allows up to an 0.810-inch diameter wheel.

This means that those pressure excursions that you hear from an ignition cutout are directly affecting the lifters with severe impact loads. If you refer to the sidebar reference from the Bosch Automotive Handbook, you’ll see that one of the disadvantages of needle bearings is they are highly susceptible to impact loads. The result of these hammer-like loads can be a tiny indentation in one of the needle bearings. When this occurs, the needle will stop spinning and begin to slide. When this occurs, it creates unwanted friction, and will soon fail. Once that occurs, all the engine builder can do is sweep up the despair in a dustpan.

Advantages and Disadvantages of Roller Bearings

These remarks can be directly attributed to the Bosch Automotive Handbook – 3rd Edition on page 275:

Advantages                                                         Disadvantages

Low static coefficient of friction                         Sensitive to impact loads

Low lubrication requirement                              Sensitive to dirt

High precision

While Godbold’s example is telling, it is not all-encompassing. Any engine that has experienced more than a passing episode of loss of valve control — commonly referred to as valve float — may also be a candidate for a bushing lifter. This is often harder to detect, but good engine builders know that if the valvespring retainer needs to be separated from the locks by striking the retainer with a hammer and a socket, then that valve has experienced a loss of control.

What has helped improve durability is the latest generation of lifters employing pressurized oil feed to the roller as with this Morel Black Mamba lifter. Both styles of lifter benefit from direct lubrication but bushings demand much higher oil flow. Never restrict oil to bushing lifters.

One of Godbold’s time-honored examples of the consequences of loss of control is winter Olympic ski jumpers. As long as a jumper lands on the sloped portion of the ramp, they easily survive the landing. But, if they excel in their launch and land on flat ground, it’s going to be catastrophic to legs and ankles. The same is true of a roller follower. If it separates from the lobe and then reconnects on the closing ramp of the lobe, there will be minimal problems. If serious valvetrain deflection projects the lifter off the nose and the roller lands on the lobe’s base circle, the impact load will be catastrophic.

Typical Roller Lifter Specs

Lifter Diameter Wheel Diameter Slower Wheel Speed
0.842 0.750  —
0.875 (Jesel) 0.760  1.3%
0.904 0.800 6.6%
0.904 (Mopar) 0.815 8%
1.00 0.910 17.6%
1.00 0.920 18.5%
1.062 0.920 18.5%
1.00 (wheel guided) 1.220 38.6%

These percentages are based on the 0.750-inch wheel diameter. So a 0.904 Mopar lifter with an 0.815 wheel diameter will turn 8 percent slower than a 0.750-inch wheel diameter GM 0.842-inch lifter.

New techniques in cam design are now making it easier to achieve higher engine speeds while using the same — or oftentimes lower — spring rates. All of this offers plenty of reasons to retain needle-bearing lifters for many applications. To reinforce this concept, Godbold says, “The only time I’d run a bushing lifter would be because I know the engine will hit the rev-limiter on a regular basis. There are no bad needle bearings out there.”

The Morel Black Mamba lifter body is machined from billet steel and is capable of extreme RPM with 400-pound seat pressures and open pressures of 550 to 1,000 pounds.

This is not to say there aren’t plenty of racers out there using mechanical roller cams with bushing lifters. As we alluded to earlier, there are caveats to this selection that must be attended to with close attention. Troy LaCrone is famous among the Midwest street elite, running dark blue, nitrous-assisted Camaros. The one that has received the most attention was his 572ci big-block Chevy, nitrous-assisted ’68 Camaro that consistently ran deep into the sevens with the help of a set of Morel Black Mamba bushing lifters.

LaCrone crashed that Camaro in testing and luckily was unhurt, but the car did not fare as well. He has since built a tube chassis ’69 Camaro, but his earlier F-body was famous for logging significant street miles with zero valvetrain issues. LaCrone competed for two years in Drag Week and finished second in the Pro Street class with a five-day average of 7.777 seconds at 172.9 mph. Drag Week is famous for culling out weak valvetrains and the number of engines wounded-in-action is legendary. Yet, LaCrone has completed two Drag Weeks with his Morel Black Mamba lifters that are still racking up street miles.

You may have heard references to lifter thrust angles causing issues. The thrust or pressure angle as illustrated in this photo drawing is created as the lifter accelerates on the opening side, creating a vector force in the direction indicated.

Once You’re Set On Bushings

Among the conditions that should be met when considering a set of bushing style lifters is to ensure a consistent volume of oil to the lifters at all times. Lake Speed, Jr. is a recognized tribologist, which is the fancy term for an oil engineer. He has some excellent recommendations for anyone considering the use of bushing-style mechanical or even hydraulic roller lifters.

According to Speed, bushings require high oil flow, so the first recommendation is to never restrict oil to the lifters. But just as importantly, a thick oil film is essential to creating the lubrication barrier necessary to minimize wear. “A semi-synthetic is actually really good for roller lifters,” says Speed.

“The needle bearings really like the higher pressure viscosity coefficient of the synthetic and mineral blend.” Speed also mentioned that viscosity is really important because bushings rely on a fluid film for protection. For these lifters, a 15W-40 or 20W-50 blend would be ideal.

This is a special dial bore gauge from Diatest that can accurately measure lifter bore diameters to determine clearance. Excessive clearance should be avoided for a number of reasons. Jesel recommends 0.002-inch (cold) for iron blocks and 0.0012-inch for aluminum blocks with a recommendation to heat the block before firing the engine.

All of this bushing lifter talk should not be misconstrued as a condemnation or criticism of roller-bearing lifters. The guys at Jesel, for example, are big supporters of roller-bearing lifters. If high spring loads and excessive RPM are part of a competition engine, then larger diameter roller lifters should also be an essential part of that plan. That should be matched with a larger cam core diameter as well.

According to Erson Cams’ Jack McInness, a 5mm increase in cam core (journal) diameter should be accompanied with a 0.020-inch wheel diameter increase to reduce wheel speed with the larger camshaft. EngineLabs followers may remember the story on Dan Jesel’s Equal 8, which was a custom-built clean-sheet-of-paper race engine that was aimed at Bonneville competition, where the plan is to spin the engine past 12,000 rpm.

This is what happens when roller bearings fail. In this case, the bearings escaped into the engine causing tremendous internal damage to pistons and cylinder walls. The owner said his first indication was when the engine started to squeak. Religiously checking lash can often identify the lifter before it fails.

To that aim, the engine uses one-inch-diameter lifters using a 1.220-inch roller wheel that is encased in cartridges fitted to the custom block machined with a massive 3.50-inch cam tunnel. These lifters use roller bearings and not bushings. In fact, they are the same style of roller bearings used in all Jesel lifters and what Jesel recommends if you are serious about building a competition engine.

On a more conservative level, this author has never experienced a failure with roller bearing lifters, despite running engines through some grueling competition, including two Pony Express open road racing events back in 1997 and again in 1998. We held our Lingenfelter-built 420ci small-block Chevy to 6,000 rpm over a period of 33 minutes where the oil temperature, even with an oil cooler, hit 300 degrees.

Larger lifters are best combined with a bigger cam journal diameter which also improves durability with more accurate timing. The Jesel cartridge lifter shown here is an example of a one-inch diameter lifter with an even larger 1.220-inch wheel.

Despite this brutal treatment of the synthetic oil, the lash never changed after two full races and multiple street events. When we finally replaced the lifters, they appeared as if they could easily go another 20 years. This engine never exceeded 6,500 rpm, but we also ran some conservative spring pressures. The engine never exhibited valvetrain distress and we liberally changed oil and checked lash after every extended competition event.

We were using a set of Comp mechanical roller lifters that were merely splash-oil lubricated and not nearly as good as the company’s current Endure-X lifters using tool steel axles and fed with pressurized oil directly to the bearings. One other advantage to the newer generation roller lifters is that many of them are now fully rebuildable.

Between Comp, Isky, Jesel, Morel, Johnson, and the multiple other notable lifter companies, there are multiple options to choose from when deciding on the best lifter for your application. In the past, roller bearings were the only path. Now you have a choice.

While Jesel emphatically recommends roller bearing lifters, they do offer a bushing style lifter on some lifter models based on customer demand.

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About the author

Jeff Smith

Jeff Smith, a 35-year veteran of automotive journalism, comes to Power Automedia after serving as the senior technical editor at Car Craft magazine. An Iowa native, Smith served a variety of roles at Car Craft before moving to the senior editor role at Hot Rod and Chevy High Performance, and ultimately returning to Car Craft. An accomplished engine builder and technical expert, he will focus on the tech-heavy content that is the foundation of EngineLabs.
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