Originally Posted by got_nitro

Carbon build up on the top of the piston could also be "compensation" for more compression. That dosent mean if you dont want to clean the build up off the top of the piston, you have to ADD a shim either. If you have to remove a head shim to make up for power loss due to a worn sleeve, (in the end thats what your saying to do) then you would HAVE to run a lower % of nitro and change to a lower heat plug. If you dont you could have some pre-det happening. You dont want the top of the piston to start to pit. Not to mention the unnecessary stress and wear you will be putting on the rod and wrist pin. In the end it's beter to have the sleeve pinched, not remove a shim on the same plug and fuel.


Now, if there is a engine out there that requires you to remove a head shim after break in, thats a first to me. I have never used one.