Thought i would start a new thread with the below info as think its quite a rare picture
Quoted for my Track car thread:
As Ryan is getting his cylinder head built by a local company, they were asking about how much clearance there was from the valve ports to the water jackets etc.
As it happens, I've got an old scrap cylinder head kicking about, so offered to stick it through the band saw at work to find out exactly how much material it was possible to remove. Turns out it's quite a lot! The thinnest section I could measure was 4.8mm thick, so I would say that you could potentially remove up to 3.5mm without any problems.
This is a cut through the forward most valve centres of the no.6 cylinder, note the steel valve guides. (The ally band saw didn't like them! Or the steel valve seats )