stluciascooby

I have ground my heads to accommodate the high lift cams I am installing.
I have ground the side of the bucket retainers to just enough that the cams turn freely with out making any contact.
Is there a recommended clearance between the cam lobe and the edge of the bucket retainer?
Should I be concerned about head expansion and the clearances changing?
Jon

Slowboy Racing

Not quite sure I follow when you say you have ground the heads? On my heads with high lift cams the clearance between the base of the cam and the bucket was 8thou inlet and 10 thou exhaust.
The clearance will get tighter as the engine warms so it is essential to have some movement.

stluciascooby

This is not cam to bucket clearence, the cam has such high lift that it hits the cylinder head before it reaches the cam bucket so some material needs to be ground from the head.
Jon

p1mark

Obviously this kind of thing is done at the packaging stage of design. On certain bike engines i have to relieve the top of the buket bore for the same reason and 0.5-1mm is sufficient.

If you think about it the expansion of the head will make the clearance a little bit bigger, as the cams are carried above the level of the bucket bore. The heat in a head actually increases the clearance from the cam bores to the deck face - or in your case the casting at the edge of the bucket bore.

The iron or steel cams will also expand less than the ally head so basically everything is working in your favour.