A bigger C clip does not make a lifter " anti pump up". It's a safety feature incase the lifter starts to pump up. They have bigger bleed down holes designed to be used on an engine that "may pump up" ie, class racing where you are limited in valve spring choice.. The whole idea is to keep the valve train stable so pumping up does not happen in the first place. Rhoads is a bleed down lifter, not an "anti pump up". All so called "anti pump ups" are bleed down. In fact it relies on pumping up to make it work at high RPM.. and I don't know a sole who uses them.
