Wrecked my 454 this week! Have been running it all summer, and it has run well, until this week. Was running along at about 35 mph, I started hearing a noise from the motor, looked at guages, and saw zero oil psi. My boat is pretty loud, so I don't know how long it was makeing noise, and at zero psi, but I had just left the dock, so it could not have been more than 2-2 1/2 minutes. Anyways, I pulled back on the throttle, and the motor shut down by itself--VERY QUICKLY. After sitting for a bit, I tried to start it, and it did start after a few tries, but it turned over very hard, and made some knocking/pinging noises, and had little to no oil pressure. Shut it down right away, and swam it back to shore. Started it on trailer next day, and it cranked over normally, and oil had about 40 psi, but started making some noise after a 15-20 seconds.  Anyway, oil pressure at idle had only been about 45psi when cold, and had been dropping to 5-10 at idle when hot, and about 15-20 at speed when hot, so something was likely wrong before this anyways. Oil had always looked good, and never had any water in it, and boat ran fine all day before this, and at startup on the ride before the problem, so whatever happened, happened quick. I'm thinking a spun bearing, or maybe a few.  Long story short, motor is now out of boat on a pallet, a going for rebuild tommorow. I'm going to have it built for 400-420hp, so it should be pretty decent power for my boat, and still reliable. Hope to have it done and still get some time to use it before winter.

Pretty good news. One spun rod bearing. Grind crank, and one rod, clean it up, and all new bearings, and put it back together. Of course I'll be putting in a new oil pump and screen as well. Everything else looked great, so I got pretty lucky on this one.

Before you purchase a single part or assemble anything, determine why it failed.

Which bearing spun?  Where the others on their way out too?  How did the mains look?  How much oil was in the motor when you tore it down? 

X2!! Keep asking "Why" until you're completely satisfied with the answer........Or you'll be doing it again........Voices of recent similar experiences, 

Ray

High volume -- YES           High pressure -- not necessary IMHO.

Wash that thing out reeeeal gooooood so you can enjoy it for a long time.

High volume push about 25% more oil and do not raise pressure. Why not put low oil switch and wire to big light on dash. The warning light you can see however how many times can you look at the gauges when running. Also a oil accumulator is a good investment to keep oil pressure at all times.

Just got motor back tonight!  454 chevy, balanced, decked block, shaved heads, and domed pistons. 2:19/1:88 rectangle port heads. 750 Holley, on GM Performance intake. Mallory unilite distributer, and Taylor 8mm wires. power not known, but should be pretty good due to  high compression, and nasty cam.  With any luck, It will get some slow laps around the lake to break it in tommorow, and be ready to go on sunday. Here in WI, we don't have many weekends left before it gets cold, so every one could be the last ride of the season. Hope it all goes well, and as soon as I learn how, I'll put up some pics.

Man I hope you have some run in time on a stand somewhere if that's a new cam.

Good Luck, I  am still going together with my enging so I am jealous right now.  Take som pic's!       

Did learn the hard way not to give it to much gas in shallow water,- in reverse!---BIG MUDDY MESS

Douched myself pretty good many times that way! Particularly at the dock with the diverter full down............

Ray