I've spent a great deal of time going thru the posts and have found alot of useful info from everyone. I have run into a problem and would like to hear anyones 2 cents worth.

I have a 95 Mariah Z275 Davanti and live in Denver of all places. The boat came with a 454 and has about 550 hours on it. This Winter I put a B&M 177 blower on it and just spun a bearing. Probally not the smartest thing to do with an otherwise tired stock engine but ya got try. Way to go with only 4lbs boost eh?

Anyways I need to put a new engine in it and it seems that everyone in my land locked state is not very knowlegable when it comes to boats. I'm thinking a 502 but I know that this type of boat is not really a speedster with a Bravo 3 drive and all. I'd like as much power as feasable since the air is thinner up here at 5280 and would like to have something very dependable since it only has 1 motor.

Any thoughts other than buy a bigger boat with twins or trips? I'm looking to keep costs under 10k and will be pulling/installing the motor with a few capable friends. Any thoughts are appreaciated.

a used 525, but not for 10k. 502 m.p.i maybe, then spunk it up a lil bit.

Just curious
What would installing a "B&M 177 blower on it and just spun a bearing" have to do with spinning a bearing?

Well, the boat ran okay the year before with just a competely engine. I put the blower on and no more than five hours later I had engine problems, The back piston came up and hit the plug, it wasen't over-revved. Which leads me to belive a bearing moved, I mean how else can a piston come in contact with a spark plug, besides a rod and I don't have a rod knock

A bearing won't cause that unless it seizes. Sounds to me like it detonated.

Which 454 do you have??

I'm not sure of the extent of your engine damage but rebuilding would be the least expensive way out. Merc's 525sc was a very dependable engine, try to copy it. Do a search here and you'll find most of the info you need.

1-800-runsnew sells new GM marine base 454mags and 502mags for about $5200.
I also know a fellow that sells new and low hour complete 425HP/496s for about $7500. PM me if interested...

I 've got the ****ty gen 4 454 w/ 330 hp. Like I said I'm no expert but thats what the motorheads in the shop next door are telling me is the case. I really appreciate the input guys. I talked to the people at Cheaif and their saying like 23.5 for a new motor which obviously for what I'm re-powering is a joke. I found some place on here that sells a 502 crate w/ 425hp for around 5k, another guy quoted about 8k for a 496 which he claims is bulletproof. I just am having a hard time figuring out what to put in it since a bravo 3 only will handle so much, and wheather or not I should buy a crate motor and re use the blower and the carb or just go with what they send me. I'd like to go island hopping someday and don't really wanna sit somewhere 45 miles inbetween cuba and florida wishing i put something else in it. big thanks though to all for advise, I'm off to mexico tomarrow to get married. I did learn today that cast heads are the way to go for salt water...never knew that

The lower bearing shell spins to the top, stacking with the upper shell. This puts the piston higher and it contacts the head/valves.

If you were otherwise happy with the performance you might consider rebuilding the engine.

275, I know the same guy Pat does and actually just picked up a 350 from him. These are COMPLETE motors ready to be dropped in and run, no swapping parts. And the best part is they are MARINE motors, IMO thata's the only way to go. He also has the 375hp 496 motors for about a $1000 less.