Hi everyone, I am in the midst of replacing the motor in my Mitsubishi Diamante (3.5L 6G74 to a 3.8L 6G75). The 6G75 is on an engine stand with no exhaust manifolds on and I can see carbon build up. I can easily scrape it off and it is quite thin. There is also what appears like a bit of oil gunk on the valve stems (I will be replacing the valve stem seals). My question is: should I be bothering to clean all this up, and if so how would I do it? As my camshafts will be out, the valves will be in their closed position.