First a little background:
1986 26' Scarab Excel
Carbed 454 with Alpha
Last season apparently water got into the engine through exhaust, boat ran but rough, mechanic redid heads, exhaust manifolds and risers, valvetrain and reassembled.
Ran well for 30-40 hours, with the exception of inconsistent idle, winterized and stored.
Now: start it up 3 weeks ago after fluid and filter changes, ran well, started 2-3 times after this with inconsistent idle, but no other problems, found weak throttle return spring, replaced spring to get idle consistent saw oil was a touch high so removed less then a quart, oil doesnt look new, but not milky, just slightly cloudy brown.
Fired up yesterday, ran rough upped idle but had to apply throttle to get running. once running we got a loud squeak like a belt but more prominent. still running rough and now sounds like a loud tap or quiet knock. We also got some smoke out of the flame arrester. What could've happened?
The exhaust shoots plenty of water, seems to smell a little rich, and blows a little white smoke, but seems to have done that always.
Any ideas?
Where to start?
I was thinking of pulling plugs to see how they look, but this seems so sudden and unexplained, especially after just warm-ups on a hose...
Thanks in advance

I'll shoot first, and guess it's an intake manifold gasket leak. Could be sucking water in from cylinder 1 or 2 area on the head. Pull those two plugs...they are the easiest.

Thanks! Anybody else?

sounds to me like you spun a bearing. Have you noted your oil pressure? I wouldn't crank it again until I was sure.

Sounds more like a spun rod or crankshaft bearing, since it now has a knock.

Also cloudy brown oil might indicate you still have a water ingestion issue, which could also be the cause of a spun bearing...

My point exactly.

Sooooo... this motor needs to come out to inspect bearings?

If its turns out badly for you I have a fresh 454 complete ready to drop in, just put on your accesories.

Take your oil filter off and drain it into a clean pan and let it settle (look at the oil later for any unusual metalic residue). Get a hacksaw (or cut-off wheel on a die grinder, or band saw) and cut the top of the filter off. Pull the filter material out and seperate the pleats. If you see copper...or basically any "flaked" material...you motor is in trouble sir.