Plug read, opinions needed

Hysteric said

That grey is most likely exhaust gas. Restrictive exhaust or too much overlap?

To be honest in my opinion that second one is very good. What the spark plug tells you is the mixture AFR and quality of the mixture at time of ignition. Just because you give the cylinder a certain AFR doesn't mean that's what it is at the plug at time of ignition. Timing mark is myth.

Good to see people actually reading plugs instead of just an O2 gauge.

Click to expand...

This is a marine application and the overlap is about as high as I can run with the exhaust outlets under water. The cam is a comp extreme marine 284 hydraulic roller. 230/236 @050 .557 lift. Your restricted exhaust suggestion has me thinking. They are an old set of Gale banks water cooled log style headers and definitely are more restrictive than a set of headers. But turbos make backpressure so any exhaust with turbos at the end could be considered restrictive.