How does regrinding the standard cam profile to say a BD12 work? The BD12 has more lift than a standard cam.
Common sense would tell me that you cant add more material??
Does the whole circumference get grinded and then use a longer follower or what?

Any explanation appreciated

 

They decrease the base circle, so they have more room to build up on the lobe/s.
The tappet being hydraulic will stretch to accomodate the extra gap putting the follower back on base,
tabetha