The advantages of a roller cam include: no need tobreak-in the cam on initial startup, the lifters can be reused if youchange cams, the open and close ramps of the lobes are faster, givingyou more torque and horsepower for any given grind, roller cams wear ata fraction of the rate of standard cams, and roller cams can use thelatest blends of motor oil with out the zinc, so no additives areneeded.
A few things are different about a roller caminstallation. A standard cam is ground in a way that causes the liftersto rotate during operation to minimize wear. This design causes the camstay in place by itself as the engine turns. The roller cam design doesnot need to rotate the lifters, so it will “float” in place duringoperation.
To keep the roller cam from moving too much, you need to usea cam button between the cam cover and the cam gear to hold it inplace, and a Torrington bearing behind the cam gear to keep the camgear from damaging the block. You will need to set a camshaft end playby using shim washers (similar to setting crankshaft end play). Lastly,you need to make sure that your distributor drive gear on the cam, andthe drive gear on your distributor are compatible.
Roller cams arehardened steel, and if mated to a soft iron distributor gear, it wouldwear out the distributor gear quickly. Most cam makers press on a softiron gear on the camshaft at the factory, so in many cases you need todo nothing. However, if your roller cam has a hardened gear, the cammanufacturer usually sells a matching hardened steel distributor gearfor you to use.
If you are retrofitting an older engine thatdid not use a roller cam from the factory, you will need to use a retrofit roller cam and retro fit roller cam lifters. These parts have thecorrect geometry to go into an older engine and have their own uniquepart numbers. Also, you will need to use shorter pushrods for a rollercam, and the manufacturer will have the correct length ready for you.If your engine is newer and has a roller cam from the factory, you willuse a roller cam and lifters that are designed as direct replacements.Roller cams will work with any rocker arm design.
Going to aroller cam upgrade is one of those few times where you can really tellthe difference it makes when you drive. Roller cams are more expensive,but if you can convince your customer to come up with a few extra bucks, it will really be worththe investment.
– Tech Tip courtesy of Summit Racing