Have something strange - pulled off my intake manifold today - noticed that the bolts were just barely "tight". Just a 1/16 of a turn and they were finger loose. So, that was strange, but even stranger when I got the intake manifold out of there, I noticed, on the floor of the intake "runner" in the head going to the valve was "sludge" on the bottom of the runner.
It was thick - I bet in some spots it was 1/8" thick when I scraped it out of there, and it was black as night and was somewhere between oil and dirt. One part had a lip sticking up far enough that I'm pretty sure I know where the 20-30 hp that I lost this year went.
I scraped it out, then drenched it in carb cleaner and rubbed it down. It's still somewhat "black".
Any thoughts on what might have caused it?
Do I need to get the port "shiny" again? (and if so, any thoughts how with the head still installed?)