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Originally Posted by patrickt
Excalibur is right on the money -- breaking in a solid lifter cam takes extra work and is a little risky. Breaking in a roller is easy. On the street though you're not going to notice any performance difference between a solid roller and a solid flat. So, if you elect to go with the solid roller be careful about restricting the lifter galleys as you do with a solid flat tappet. Low FE oil pressures and street idling can limit the life of the solid roller. I believe the problem of a few years ago with the cheap foreign lifters has now passed us by, but perhaps Barry R. could chime in on that. Other than the break-in issue, there is no real benefit on a street machine to going with a solid roller over a solid flat and, with the solid roller, you still have the specter of limited life. Makes it all simple, huh?  |
I don't know if I agree with that. Because of the cam lobe profiles of a roller cam are much more aggressive and open and close the valves faster (whether solid or hyd roller) than a flat tappet cam, you will get better performance from a roller than you will from a flat tappet cam with similar or even slightly greater duration. The aggressive lobe shape of the roller cam effectively opens and closes the valves faster (as compared to a flat tappet cam) which allows the valves to stay open longer, thereby creating more "area under the curve" which provides the cylinders more time to fill at any given duration as compared to a flat tappet cam with the same duration. Or put another way, you can run a smaller duration roller cam (which means better throttle response and better idle quality, i.e., more streetable) but still have as much if not more power than you could get out of a flat tappet cam of the same duration or even slightly larger duration.
IMO, hyd roller is the way to go for a street cruiser. You eliminate the break-in problems associated with flat tappets, don't have to worry about roller bearings in solid rollers, and because of the cam lobe profiles, can run a smaller cam with better street manners without sacrificing performance of a larger flat tappet. Needless to say, I am having one installed in my motor as we speak.
