SBC with Flat tappet hydraulic or solid lifter does not need a cam button. The camshaft lobes have a very slight side taper ground into them, this causes the flat tappet lifters to spin in their bores reducing wear and also causes a rearward thrust. P.S. I just disassembled a High dollar SBF with roller cam that someone forgot to put the cam gear bolt in. It evidently had ran for about 2 minutes before catastrophic engine failure. This destroyed a set of new edelbrock heads etc. My friend bought the motor for $400.00 for the block. I don't know who assembled the engine but gee, I think a guy would notice something like that.