Another Lee's Speed Shop Exclusive!
These valve spring shims are machined specifically for Harley Davidson Knuckleheads. Available in three variations: .016" / .030" / .064" thick. These are machined to fit on top of the lip of a Knucklehead valve guide and inside the recess of the Knuckle lower spring collar. You won't find these at your local auto machine shop!
If your valve springs need to be shimmed, and you install a shim with a large I.D. that straddles the guide, then your springs no longer put pressure on the guide. Since the guide holds the lower tin in place, this lack of pressure can lead to a premature loosening of the tins and resultant oil leaks!