Motor Rebuild Ques.

[skiwesser]

How exactly do you check piston/valve clearance?
All I know is what I've read: put some clay on top of piston, mock up head & turn over by hand? If the valve is gonna hit the piston will it not bind up? Can any piston be notched for clearance? Is it expensive to have them notched, how do I check and then translate to machine shop where to notch them?, how deep?

Inexpereance sux!
Thanks

P.S. A while back I ran a desktop dyno of a stock motor and the power really jumped when i retarded the stock cam so I was concidering doing that ,but 4* seems like a lot?
I don't have that program any more but it seems I remember that the retarted cam really brought up power anyone else tried this with their car?