head rebuilding info

[shortysclimbin]

How much is everyone having the machine shops remove from their heads? What are the max and min specs for removal?  What finishes are you going with and why? 

[Rabbit on Roids]

im pretty sure the general consensus is to only remove as much material as is required for a flat deck. remove too much and it starts adding compression.

[Vincent Waldon]

What are the max and min specs for removal?

According to VW, the answer is "0".. as in "the head is not to be resurfaced". 

Having said that... millions have... but you're on your own in terms of "specs".   

[rabbitman]

im pretty sure the general consensus is to only remove as much material as is required for a flat deck. remove too much and it starts adding compression.

I don't think it would ad compression since the head is already flat. AFAIK the problem would be the valves would sit closer to the pistons so, depending how much you removing, you'd have to start cutting the valve seats deeper into the head.

[Rabbit on Roids]

either way, the head and everything in it will be closer to the pistons. the combustion chambers will be smaller. compression will go up. it may not even be noticeable, but it will go up, might only be a teeny tiny bit tho.

[Rabbit79]

If a person is going to re-surface a head, what do you do about the pre-chamber inserts? Do you leave them in and shave a little off of them as well, or do you take them out and let them protrude out of the re-surfaced head a little more?

[Mark(The Miser)UK]

If a person is going to re-surface a head, what do you do about the pre-chamber inserts? Do you leave them in and shave a little off of them as well, or do you take them out and let them protrude out of the re-surfaced head a little more?

Skim a head? Do it youself with carbourundum paper on plate glass.
Leave prechambers in.
Skimming raises compression. Slightly from prechamber channel, but maybe 20 times that from valve recesses How many thou?
I dunno, but I may have taken off 20 thou in my over enthusiasm.  No leaks, and no clashes of valves.