[Brian]

I always use the aluminum press on gear. What I do is, after oiling the nose of the cam, is heat the gear...this expands it and allows it to drop on and gives enough time to correctly orient the marks. I once experienced a press on timing gear that moved in service, throwing out the timing. As a consequence, every gear I fit now, after checking valve timing with a degree wheel, I scotch key into place. This prevents any lateral/radial movement of the gear.