Well,
 On my BBC 454 It appears I have one cylinder that is running lean. What would cause this? The boat has sat for 5 years and I have taken it on one test run since cleaning her up. I removed the Headers today and found #6 Cylinder on the header side pretty white. I pulled the plugs and found #6 to be slightly white. I didn't take note to how the plugs looked before the test run but I did spray some high temp paint in the header tubes  (got a little carried away with the paint that day) Would the water mixing with the rust and paint cause this to look worse than it is?  I'm a little confused on how one cylinder can run lean. The boat runs great, no hesitation, bogging, smoke or pinging. It idles fine and accelerates smoothly. The plugs are old and need to be changed, as well do the wires but I doubt a faulty plug or wire could cause that cylinder to run hotter... can it?

any input would be very helpful,
James

EDIT: Forgot the pics, the flash might be over exaggeration the whiteness a bit. It was getting a little dark when I took the pics but I saw them during the day and they didn't look as white as in the pics

Could also be a sucked intake gasket....Stupid common on an aluminum intake.

GT

Ahh  why didn't i think about that? It's not aluminum but it looks like it's just gasket maker on there, quite possible after sitting for some time the gasket maker is not doing it's job anymore.

Do a compression test, a bent valve will do exactly what you state.
GT

Really? I've had bent valves before but I've also had engine symptoms along with them... but then again I've never had a bent valve in a boat, I will check the compression tomorrow.

Thank you for the help,
James

Okay, I checked the compression on the other bank and got similar results. I checked for air leaks at the intake with some carbon spray and the idle did not change I know the plugs are old and need to be replaced. I asked around and have found a faulty plug can run hotter. So I guess I'll change the plugs and re-check