Another mercruiser 470 dilema

[redneck jeaven]

I recently purchased a 1978 Wellcraft Suncruiser 255 for $2500 so I have extra dollars to make it what I want. Dilema, it has twin mercruiser 470s in it and one of them has a problem. When I picked it up the head was off one of the motors. I've read a lot about swapping for other motors but with twins I don't have room to make many change without major reconstruction. Since I really like this boat I'm thinking I should buy two remanufactured long blocks, but I don't know the best place to buy, or if later years will fit the outdrive. Thoughts, comments..... and Thanks for reading.
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[Scott Danforth]

welcome aboard

are you sure the 470 doesnt just need a head gasket? the head gasket is a common failure point.

 

[Bondo]

Since I really like this boat I'm thinking I should buy two remanufactured long blocks,

Ayuh,.... Welcome Aboard,... I think you'll be hard pressed to find reman crate In-line motors, other than the 3.0ls,...

I-6s maybe, 470s, I really doubt,...

 

[Scott Danforth]

if your center to center spacing is over 34" you can go with V motors. manifolds will be darn near rubbin

you could switch to 4-banger diesels, however you would need different drives

 

[redneck jeaven]

Thanks for the responses. Scott I haven't looked farther than the head being off. I really like the thought of diesels. Do you lnow how much sringer change and outdrive fitment whould be involved. Bondoi, I have seen some around $2500 each and read about iron block motors, however the point to it all is a dependable nimble boat and less future problems. Ha, is there such a thing on the water. I want to do it right the first time.

 

[Scott Danforth]

the merc key-hole is pretty much the "standard". a couple of Cummins QSB-250M's (3.9 liter 4-bangers) would fit nice in front of bravo drives.

However with a 40 year old boat, first make sure you are not needing to replace the stringers and transom due to rot (highly probable)

assuming your boat is rot free, I would start by pulling the motors, and going thru both of them. wont take long to determine if you have something that simply needs a head gasket or a complete over-haul.

if your boat has a rotten transom, you can put in anything you want.

assuming you have only one bum motor, plenty of 470's being sold if you wanted to drop a like for like in the hole as well.

 

[stonyloam]

Well seems the first thing to do is find out if the all together engine runs. If it does, do a compression check to determine the health of the head gasket. If all checks out with engine #1, then find out exactly is wrong with engine #2. You can tell a lot just by looking at it. Are the cylinder walls smooth, not scored. Same with the head, take it to a shop and have it checked out. If it is just a head gasket you could be back in business for a few hundred bucks. Once you fully evaluate what you have, then you can make plans. Repowering is not simply dropping in new engines, the outdrives need to match the engines, and it can get really expensive.