outboard to inboard conversion

T

taqwache

Member
ok here is a good one. i got a 78 V20 steplift that has been in the family since 1979. it came from the factory with twin 75hp mercs. after 10 years or so of saltwater use, those went bad and my dad repowered with a single 175 mariner. now after another 10 years or so of saltwater use, it has also gone bad along with the transom. since then the boat has been sitting for 5 plus years in his back yard. now me and my dad plan on restoring it. i found this site and noticed that these boats also came with inboard/outboards which is what i want to use. since the whole transom needs to be replaced anyways, how hard would it be to just mod it for and inboard/outboard? i was planing on useing a modified 400hp 6.0L gen3 chevy with a mercrusier alpha one. i know it will be difficult but that does not matter. i am very mechanicly inclined but i dont have to much boat experience. although i can learn very quickly. i can build a motor for almost free but i will have to buy all the other marine parts. what do yall think? what else is different from the two styles of boats (OB and IB/OB) that will be a challange?
 
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You won't get much support with that mod I'm afraid. Most everybody does the opposite. I'm sure it's do-able though, but will require a "boat load" ( ;D) of structural mods to be able to bolt an engine into the hull. Your choice of engine and drive is curious to me. Why go with that engine? An Alpha 1 of any generation is not a good choice for anything above 300 hp. You would be much better off with a Bravo drive. I would spend the $$ on a good OB after restoring the transom.
 
You won't get much support with that mod I'm afraid. Most everybody does the opposite. I'm sure it's do-able though, but will require a "boat load" ( ;D) of structural mods to be able to bolt an engine into the hull. Your choice of engine and drive is curious to me. Why go with that engine? An Alpha 1 of any generation is not a good choice for anything above 300 hp. You would be much better off with a Bravo drive. I would spend the $$ on a good OB after restoring the transom.
 
I'd have to agree with frayed and I'm a Mercruser Tech by trade. Thats way too much hp for this hull, it would go to waste. The bravo would be a better choice for that engine as well, you could git an Alpha to hold it if you wern't dogging it too hard. Best solution if you want to have an I/O. Trade your boat to some one with an I/o boat that wants to convert to an outboard. Espcially in salt water, your just asking for more work. If you really want an I/O, try a Volvo 5.7 320 HP with the XDP composite drive. Thats a slick package and salt won't touch it( I service a pair XDP's behind twin 8.1's in a 34 Cruiser). If you allready have the engine, try finding a used 22 Velocity(Regal sold them for a while), thats a boat that will put that motor to good use
 
I'd have to agree with frayed and I'm a Mercruser Tech by trade. Thats way too much hp for this hull, it would go to waste. The bravo would be a better choice for that engine as well, you could git an Alpha to hold it if you wern't dogging it too hard. Best solution if you want to have an I/O. Trade your boat to some one with an I/o boat that wants to convert to an outboard. Espcially in salt water, your just asking for more work. If you really want an I/O, try a Volvo 5.7 320 HP with the XDP composite drive. Thats a slick package and salt won't touch it( I service a pair XDP's behind twin 8.1's in a 34 Cruiser). If you allready have the engine, try finding a used 22 Velocity(Regal sold them for a while), thats a boat that will put that motor to good use
 
If you are going to do the transom restore, I would suggest you close it in completely and add a full bracket to the back and add a single 150 etec or similar motor. Nothing bigger and you will have a mid forties performer that will be less maintenance intensive and generally more reliable across the board. Actually if you add a 115 - 150 to a bracket on the back of that boat you will have the best performance package you can have, it will be very quiet behind that full transom and you will increase the sea worthiness of your V at the same time. JMHO
 
If you are going to do the transom restore, I would suggest you close it in completely and add a full bracket to the back and add a single 150 etec or similar motor. Nothing bigger and you will have a mid forties performer that will be less maintenance intensive and generally more reliable across the board. Actually if you add a 115 - 150 to a bracket on the back of that boat you will have the best performance package you can have, it will be very quiet behind that full transom and you will increase the sea worthiness of your V at the same time. JMHO
 
OK taq ... ya stated what ya wanna do and everybody's tryin' to talk ya outta it ... fact is, you can do most anything your wallet and skills can cover w/these hulls ... if I were doin' what yer talkin' about, I'd take the floor deck up and beef-up the stringers to handle the weight/power of the motor you want ...while yer that far into it, take the cap off and replace the notched transom w/a full one ... keep weight in mind, but put it all back STRONG ... post some pix here thru the modification ... I'd like to see it happen ... oh yeah...I think the '78 had a small gas tank (42?) ... be a good idea to add more fuel capacity while yer at it ;) ...
 
OK taq ... ya stated what ya wanna do and everybody's tryin' to talk ya outta it ... fact is, you can do most anything your wallet and skills can cover w/these hulls ... if I were doin' what yer talkin' about, I'd take the floor deck up and beef-up the stringers to handle the weight/power of the motor you want ...while yer that far into it, take the cap off and replace the notched transom w/a full one ... keep weight in mind, but put it all back STRONG ... post some pix here thru the modification ... I'd like to see it happen ... oh yeah...I think the '78 had a small gas tank (42?) ... be a good idea to add more fuel capacity while yer at it ;) ...
 
Welcome to the site.
I'm with them about bracket. Bracket and twin 90's would be nice but at the very least go bracket.
POST SOME PICTURES!! ;D
 
Welcome to the site.
I'm with them about bracket. Bracket and twin 90's would be nice but at the very least go bracket.
POST SOME PICTURES!! ;D
 
BRACKET<BRACKET<BRACKET!!!!!!!!!
;D ;D ;D
Wellcraft2207094.jpg
 
I converted from a I/O and its the best thing I have ever done!!

Go Bracket Young man and never look back!!
 
I converted from a I/O and its the best thing I have ever done!!

Go Bracket Young man and never look back!!
 
i didnt think i would get much support for this idea but that is ok. a bracket with a single OB is an easier mod and makes more sence if you want a good fishing boat but i am looking for something different. first off, i what to use this type of motor because i mod these for a living and i have enough parts laying around to build several engines intake to oil pan if i wanted to. if i were to go with a FI 2 or 4 stroke OB and later have problems with it, i would not know much about fixing it plus i dont have any hookups were i could get parts from for cheap. also, although this boat will mainly be used for fishing i plan on doing other stuff as well. like going several miles off shore to fish, doing long hual cruises from like houston to brownsville down the intercoastal camping on unknown islands along the way, and of coarse there is the water sking which i love to do. i just feel like an inboard/outboard would be better for me for stuff like this. plus when stuff breaks i could fix it easier. and then there is just the cool factor of having the only V20 with a 400hp LSX (gen3 chevy) motor that i probably will never be able to run wide open without killing my self. on the alpha or bravo deal, i just figured it would be easier and cheaper to get ahold of an alpha sterndrive then a bravo since there is thousands of them out there. that choice will have to be made up later since the main thing i have to think about is how much trouble this is really going to be.
 
i didnt think i would get much support for this idea but that is ok. a bracket with a single OB is an easier mod and makes more sence if you want a good fishing boat but i am looking for something different. first off, i what to use this type of motor because i mod these for a living and i have enough parts laying around to build several engines intake to oil pan if i wanted to. if i were to go with a FI 2 or 4 stroke OB and later have problems with it, i would not know much about fixing it plus i dont have any hookups were i could get parts from for cheap. also, although this boat will mainly be used for fishing i plan on doing other stuff as well. like going several miles off shore to fish, doing long hual cruises from like houston to brownsville down the intercoastal camping on unknown islands along the way, and of coarse there is the water sking which i love to do. i just feel like an inboard/outboard would be better for me for stuff like this. plus when stuff breaks i could fix it easier. and then there is just the cool factor of having the only V20 with a 400hp LSX (gen3 chevy) motor that i probably will never be able to run wide open without killing my self. on the alpha or bravo deal, i just figured it would be easier and cheaper to get ahold of an alpha sterndrive then a bravo since there is thousands of them out there. that choice will have to be made up later since the main thing i have to think about is how much trouble this is really going to be.
 
Well it looks like you have made up your mind!!

First thing is that you are going to have to beef up them rear stringers to take the load!

Next I think you are also going to have to widen the engin box, cause its going to be tight!!

Look at this thread, Cliff just repaired his rear stringers and reinstalled a motor

http://www.wellcraftv20.com/cgi-bin...Repairs;action=display;num=1177852167;start=0


When you get started take lots of pictures, and start a new thread so we can follow along and help were ever we can!!

Good Luck!
 
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