I have a pair 99' Carb'd 500HP blocks that were stroked 4.25" and all new equipment from crank to top end replaced. Eng. hours = 20. Dyno HP @ 650. The port motor is using about 2 quarts of oil every 1.5-2 hours. Oil: Valv VRI 20-50. Engine starts and runs great no smoke, no power loss. There is considerable "black exhuast" film that builds under the swim platform and ladder area. (Not oily, but dry) Pulled plugs and there was considerable black build-up on all plugs, and oil at base of plug and threads.
Starboard motor is perfect has not used any oil and the plugs are running a little rich, but no build-up and are clean. Plugs: NGK V Pwr 8. Any help or suggestions would be appreciated...
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Ouch!........ who built the motors? Someone may have put in a few rings upside down. If a couple of second compression rings were put in upside down the oil consumption would be horrendous. The only other explanation would be the cylinder walls are glazed and the rings never seated.

You might check intake gaskets. If anything was machined you may have a problem angle of head to manifold being off a bit and trouble with gaskets sealing and sucking oil. Just a thought,

Thanks Reed & Paradigm, I was getting nervous no one wanted to reply back to me!!! A&W Performance built the motors out East, but I am in WI. Still waiting on spec sheets on the motors. Motors are in a 388 Slingshot. I am hoping it is either the Power Valve/Float Levels in Carb. I heard this may push a ton of fuel and wash the oil down past rings??? I have a strong feeling although that it will turn out to be the Intake like Paradigm suggested. Just sucks because I only have 10 hours on the boat.
I just had the oil pan exchanged and the cylinder walls looked perfect, not glazed... The motor ran great for about 10 hours, and has just started to get worse and steadily using more oil. Any other thoughts or suggestions are EXTREMELY APPRECIATED

Matty,
Start the engine and let it idle. Take off one of the valve cover breathers and spray about a ten second shot of carb cleaner into the valve cover. If the idle speeds up or changes a few seconds later, you can almost bet its the intake gaskets.

If it ran ok for the first ten hours, I doubt that it would be a ring problem.

Bill Koustenis
Advanced AUtomotive Machine
Waldorf Md

Start with a leakdown test.

Had the same problem with my motors when they were freshend last year,,, turned out the PCV valves were not strong enough to close after the new cams were put in,,,, and the carbs/blowers were sucking the oil out of the pan !!! simple fix , once we found it ,,,, Good luck!

RHC

You might have gotten a bad set of valve seals on that one motor . It could cause the same condition your talking about. Brian

Awesome ideas from all - thanks - keep them coming!!!

RHC - I know the carbs & cams were built up pretty heavy to go with the rebuilds. What did you do for the PCV Valve replacement? Did you go with new stock PCV Valves or Heavier Duty PCV Valves? Would my Merc 500HP's have PCV Valves?

Check'd the devil motor today. THe line from back of carb to top of intake was indeed loose and the grommet was worn out. I ordered a new PCV Valve and Intake Grommet will be in tomorrow. My hopes is this will cure thristy motor, but I still think its intake related!??!
Question: Will a stock 500HP PCV Valve be strong enough to open/close on a storker 540?????