525sc...runs great, but at times it does seem to load up a bit at idle, & more often when cold. I also have the black transom after a run, but I figured it was just due to the engine running a bit on the rich side due to the blower. I removed the plugs & they were soaked with fuel. Again, it runs real good, I don't have any bogs, or hesitations. The plugs are the NGK R5673-8 which is the version of the AC MR41T (which is what Mercruiser recommends). I did wonder if I may have a blown power valve, but it doesn't act like it.
So, I'm wondering if maybe the coil is just not firing like it should. I'm sure it is the original one, & I was just thinking about installing an MSD Blaster coil, a new set of plugs & wires.
Or is this just the way this engine runs?

Too high octane maybe??

sounds more like the power valve to me...pull the metering blocks and ck for wettness in the valve...Rob

I do run 92 octane, but that is what Mercruiser says is the required fuel.

I've always had an engine bog or hesitate when the power valve is blown.
It may be worth pulling the blocks off to check....
Thanks....

When the boat is in the water idling remove the flame arrester and look down the carb. There should be no visible fuel dripping front or rear. If there is, first check float levels. If they are good go to the PV. I run the same blowers and carbs but #9 plugs and havn't had the loading up issue. I highly doubt it is ignition related.

I will check that...That is what I should've checked first, but it's been so long that I've run carbs, I've forgotten the "simple" troubleshooting things....
The #9 plugs...is that a hotter plug?
Thanks for the input...

I don't think the 525SC carburetors had powervalves. I think they had #98 jets all around, which would make it rich during cruise operation and OK at WOT.

98s all around and 6.5PV front and rear. #9 plugs are cooler than 8s.

Hey Rick,

Was going to send you a pm but you seem to have that turned off.

Your old Donzi is getting one of Eddie Young's 850+ hp engines right now.

Sounds like you are enjoying the Sonic.

Bill