There are no shims in the top of the solid followers of a ST170. If it had biscuit shims like the standard Blacktop, with the cam lift they either wear rapidly or get flipped out.

Adjustment, if needed, is by changing the whole follower. Like the shims, they come in a range of lengths varying by .03 or .06mm. Cost around £16 each though. Still cheaper than Kent Solid followers and individually ground 'top hat' shims.

Never heard of excessive cam wear on any Blacktop Zetec engine. I've dismantled engines with more than 150k with no measurable wear on the lobes.

Martin