Like aftermarket rollers, factory roller cams are made from high-grade steel, and in fact, are often machined from billet stock. Also like aftermarket setups, high-quality double-roller timing sets are often used, along with bolt-on camshaft retainer plates. Chevy roller cams are stepped at the snout to interface with the retainer plate, while Ford small-blocks, which use retainer plates even for flat-tappet applications, have the step machined into the cam gear.
Cross-BreedingThere is a certain amount of parts-swapping that can be done to mix and match roller cam components. Since factory roller cams are steel, as are most aftermarket rollers, the factory roller lifters are generally compatible with aftermarket cams, and vice versa. However, factory roller lifters are limited in the amount of lift they can handle by the flats machined into the lifter bodies. If the lifter is raised too far in its bore, the bottom of the flat will contact the lifter guide. Still, the factory setups can handle a fair amount of lift. Retro-fit roller lifters can be used in factory roller blocks as well, or on factory-style roller cams in non-roller blocks. However, when a factory roller is used in a non-roller block, extra attention must be paid to ensure that the cam is retained, and that it will not be pushed back too far (by a cam button or other means) so that the timing set contacts the block. On older Chevy small-blocks in particular, the collar of the cam retainer plate must be used to serve as a spacer even if the retainer is not bolted on to the block. We've seen retainer plates with the bolt-ears cut off in these applications, or aftermarket Torrington bearing spacers. By the way, when a flat tappet cam is used in a Chevy roller block with a double-roller timing set, the area around the oil plugs surrounding the front cam journal may have to be ground for clearance.
The Roller AdvantageRegardless of whether your intent is to rip up the strip or just perk up your cruiser, your engine can likely realize the benefits of roller camshaft technology. Factory-built hydraulic roller engines have definitely stood the test of time, often displaying little or no wear to the camshaft after well past 100,000 miles. The higher-quality timing sets used in those engines also seem to have a significantly longer useful life than the nylon-geared single-chains of yore. But the best part is the increased performance the factory rollers provide without any sacrifices. Aftermarket solid rollers have opened up a new avenue for race-engine builders looking to squeeze every ounce of potential from their engines, while retro-fit hydraulic rollers allow the street/strip enthusiast to add roller technology to non-roller engines while maintaining quiet, low-maintenance motoring. What's the downside of roller cams? Probably just the price of admission, so start saving up and thinking about which roller will find its way into your next engine project.
Other Stuff You'll Need:* Cam retainer plate or button* Hardened, shorter pushrods* Hardened or roller fuel pump pushrod* High-performance double-roller timing set* Proper distributor gear
A Word On Distributor GearsAs we've discussed elsewhere in this article, roller cams are generally made from high-grade steel, rather than the iron used for typical flat-tappet cams. The problem this creates for the distributor drive gear, which is also usually iron in an engine that originally had an iron cam, is that the steel of the cam's drive gear will eat up the iron distributor gear in a big hurry. The simple solution might seem to be a steel distributor gear, but premature wear is again an issue, this time for both the distributor gear and the cam. Since the idea of consuming an expensive and hard-to-change roller camshaft isn't very appealing, the classic solution has been to use a bronze distributor gear, which is very soft and will bear the brunt of the wear between the cam and the distributor gears. The bronze gears are relatively cheap and easy to replace, so this compromise has been accepted for some time.
By The Car Craft Staff and Howards Cams
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