My1991, 454 mags had about 300 hours when I put on the 177s.My port engine never used a drop of oil all season, and it has a small leak at the rear seal. My starboard engine has been going up just slightly in oil level. The oil on the dipstick never changes color, but I am thinking that's because of the tube going so far down into the pan for pumping the used oil out. Time for a rebuild?
Also my starboard engine leaves a puddle of black soot on the water when I restart the engine after a run above 3000 rpm. If I keep the engines at 3000rpm or below, there is no soot after shutdown and restart. Only one engine does this. The other is clean. I assume they are jetted the same. What else would cause this?

Ok, a little more info. For carbs I've got BG Sea Demons. Crane Cams 242 cam, Gill exhaust. Maybe 40 hours total with the blowers. Could my PV be bad? How do I check it? I've got Holley high flow mech fuel pumps. ( don't know the size off hand) could it be bad and dumping fuel in the carb?

it could be fuel pump putting fuel into the oil. and wouldn't change oil color like water would...

My Thinking is the rings may not be holding what they should and your getting blow by. I had a similar issue. Maybe do a static compression test/ leak down. good luck

almost has to be fuel getting in there..if so engine won't live long with the diluted oil...

Hey Mark, sounds like your getting fuel in the oil. If you have marine fuel pumps, check for fuel in the vent hose that runs to the carb.

It could be something with the carbs. If the float levels are too high, it can spill fuel into the engine, when the boat rocks back and forth, or even trailering. To check for a blown PV, start the engine and look down the carb at idle, if you see fuel dripping down you may have a blown pv.

My guess is the float level might be too high. You'll want to adjust them on those particular carbs to about 1/2 way up the sight glass and see how that works. Smell the dipstick, if it stinks like raw gas, do a oil change asap. Gimme a shout anytime if you need help getting the carbs dialed in better.

Also, this winter, if you want, take you tailpipes off and get them to me. I'll have my guy weld in 02 Bungs into the tail pipes. He does it very reasonable. Then, come spring, we can fine tune the setup with my wideband, and get the jetting/pv tuning spot on. You can pop the carbs off at the same time and I'll freshen them up for you.

I'll check the float levels. The is no gas on the line from the fuel pump, but it is discolored like fuel has run through it. I thought a fuel pump either leaks or it doesn't no rpm difference. I've already changed the oil. I want to figure this thing our before I have to do another one.