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Roller Camshaft Conversions Engine Upgrade - Rockin’ And Rollin’
Roller camshaft conversions take the anxiety out of driving your classic Ford
It's been all the talk on internet forums, club meeting hangouts, and in enthusiast garages across the nation—the loss of zinc and other protective "barrier" chemicals in modern oil damaging traditional flat tappet camshafts and valvetrain components. From wiped out cams that didn't make it past initial break-in to long-serving engines simply losing valvetrain parts overnight from a simple oil change, the problem has had enthusiasts running scared for several years.
Why the change in conventional motor oils you ask? Why couldn't they just leave well enough alone? It's simple, really; major aftermarket oil companies and the parts stores that carry their products cater to the general DIY market for modern cars (considered less than 20 years old). Much like there hasn't been a Ford built with a carburetor since the early 1980s, the same can be said for a flat tappet cam application in a Ford. From factory roller cam setups (5.0L HO Mustangs for example) to more modern overhead cam valvetrains that use roller followers, these valvetrains simple don't need the protection from high pressure wear like a flat tappet cam does. When the OEs determined that additives in the oil package were affecting their emissions systems (catalytic converters, oxygen sensors, and so forth) the additive packages were removed. From an OE standpoint, it was an easy decision, as the additives were no longer needed in the first place with modern valvetrains.
Unfortunately, this decision affected us enthusiasts in a negative manner, since we stand in line at the parts counter buying the same 10W30 that the guy in front of us with an OE roller valvetrain buys. He goes home and pours in his oil and all is well. You do the same and a few days later, you have valvetrain failure. Today, the issue has been reduced somewhat by the fact that there are several oil companies that offer oil with these additive packages once again. Some are labeled as "high mileage," while some are called "muscle car oil." Still, others search out specialty oils for diesels and power sports applications and use these products due to their retention of these all-important additives. Lastly, you can buy the additive in a pour-in concentrate to add to your traditional oil change as a manner of protection as well.
While a somewhat expensive solution, converting to a roller camshaft/lifter setup is a permanent one. Whenever we see an engine being built, we strongly urge the owner to spend the extra coin to add a roller cam to their shopping list. There are several ways to add roller cam technology to a small- or big-block Ford engine build and reap the benefits of a roller cam valvetrain. The most basic is a roller cam conversion kit, which generally features a roller camshaft with a reduced base circle, roller lifters specific to the application, and some sort of installation hardware/retainer. These kits offer several popular cam grinds for street use and most manufacturers can even offer custom grinds. The reduced base circle of the cam is to allow the retrofit to work in early blocks (more on that later). Another option is to use a standard base circle roller cam with "link bar" lifters. Instead of the lifters being retained in the valley to prevent rotation, the lifters are linked to each other to prevent rotation. This allows a wider option of cam profiles, but is a bit more expensive when purchasing the lifters. The last option for retrofitting a roller cam is to use a roller-cam-ready block, either a production block or an aftermarket block. This allows the use of OE type hardware and everything just bolts together. This last option is probably best if you're planning to build a completely new engine.
One of the most confusing aspects of choosing a roller cam for many is comparing the roller cam specs to a traditional flat tappet camshaft. It's not a true apples-to-apples comparison of the specs on the cam card. Where you will find the key differences is in the lobe pattern. A flat-tappet cam lobe can only provide so much lift before the lobe literally comes to a point, which would fail very quickly. With a roller cam profile, the lobe lift can be more dramatic because of the roller cam's "broad shouldered" lobe, which provides more lift. For example, if you compare cams with similar durations at 0.050-inch lift, you'll see the roller cam has much more lift for a similar power range. Take Comp Cams' popular 280H grind flat tappet (230 degrees duration and 0.512-inch valve lift) and compare it to Comp's XE282HR roller (230 degrees duration at 0.050-inch lift and 0.565-inch valve lift). That's 0.053-inch more lift. "The lobe profiles are quite different because of the flat versus roller follower, but the engine only ‘cares' about how the valve moves and not at all about how fat the lobe ‘looks' to our eyes. The roller cams certainly give much larger gains on great flowing heads (especially the modern cast and/or CNC ports that work so well at high valve lift)," states Billy Godbold, Valvetrain Engineering Manager at Comp Cams.