whats the safest highest rpm i can run flat tappet lifters on my 466. would you guys stay with flat tappets, will they last long? I really dont wanna dish out money for a roller conversion cause its really damn expensive.
I dont think the type of lifter is going to limit your RPM. I shift my big block nova at about 7200 with a solid lifter cam. It just depends on the cam and the powerban its designed for. Big lift flat tappet cams will wear faster and probably have a narrower power band but not really a limiting factor in top RPM.
The lifter and valvetrain mass IS the determining factor to RPM, that and rotating assembly weight and balance. A flat tappet is good for higher RPM, but if it's a hydrolic, then it can limit the RPM. A solid lifter basically will not limit your RPM at all. Solid is the way to go for a race car, not much for a street car. You have to run a lot of valve spring pressure which can tear apart valvetrain parts. You can get 6500-7000, or more, out of a flat tappet lifter with the right combo.