Logo
FULL SITE MENU

70's Silverline Tri Hull

S

SILVERLINEv8

New member
Hello I have a couple questions, I have a 70's Silverline Tri Hull 17ft boat with a 250 inline 6 engine and a mercrusier unit and I was thinking about taking the 250 out and putting a v8 in either a small block or a big block not sure yet. Yes I understand that the gear ratio will be wrong but can a guy get different gear ratio? Will that outboard unit even work? If i need to use a different outboard unit which one could I use with the Silverline Tri Hull boat? Looking to gather some information because I I know this is possible and I just need to know If I can use the same mercrusier unit and just swap different gear ratios or if I will need to custom fit another unit.
 
SILVERLINEv8 said:
Hello I have a couple questions, I have a 70's Silverline Tri Hull 17ft boat with a 250 inline 6 engine and a mercrusier unit and I was thinking about taking the 250 out and putting a v8 in either a small block or a big block not sure yet. Yes I understand that the gear ratio will be wrong but can a guy get different gear ratio? Will that outboard unit even work? If i need to use a different outboard unit which one could I use with the Silverline Tri Hull boat? Looking to gather some information because I I know this is possible and I just need to know If I can use the same mercrusier unit and just swap different gear ratios or if I will need to custom fit another unit.
Click to expand...
Gear ratio in mercruiser is in the upper half of the outdrive which can easily be swapped. Alternatively you can buy a aftermarket SEI drive relatively i expensively.

Give the age before you start spending money check transom floors and stringer for rot. Would be surprised if you don’t find some.


a 4.3 would probably be a better fit for a 17 ft than a sbc big block would just be over kill. Best bet is to find a complete tear out pulleys to prop with an alpha gen 2 drive so you get all the currently supplied parts
 
Dieter said:
Gear ratio in mercruiser is in the upper half of the outdrive which can easily be swapped. Alternatively you can buy a aftermarket SEI drive relatively i expensively.

Give the age before you start spending money check transom floors and stringer for rot. Would be surprised if you don’t find some.


a 4.3 would probably be a better fit for a 17 ft than a sbc big block would just be over kill. Best bet is to find a complete tear out pulleys to prop with an alpha gen 2 drive so you get all the currently supplied parts
Click to expand...
Could I get away with using a alpha one gen 1 drive? The whole idea for this boat build is to put an over the top engine in and make the boat just a mess around boat/fun boat.
 
SILVERLINEv8 said:
Could I get away with using an alpha one gen 1 drive? The whole idea for this boat build is to put an over the top engine in and make the boat just a mess around boat/fun boat.
Click to expand...
You could use a gen one. the MC1, R, MR, alpha gen one and gen 2 drives all use the same keyhole in transom.

The issue putting a lot of power in a small hull is you can push the boat beyond its design limits speed wise and end up with chine walk.

A vortec 4.3 would get u into the 50 s sbc more so. Personally don’t know why you would invest the time in that hull but put a wake tower on it with a disco ball …

Seriously pull the drive train you have and check the structure of the boat before getting into it . Sight unseen I would put money on stringers and transom rot. Of course these can be fixed but it’s **** work to do
 
Dieter said:
You could use a gen one. the MC1, R, MR, alpha gen one and gen 2 drives all use the same keyhole in transom.

The issue putting a lot of power in a small hull is you can push the boat beyond its design limits speed wise and end up with chine walk.

A vortec 4.3 would get u into the 50 s sbc more so. Personally don’t know why you would invest the time in that hull but put a wake tower on it with a disco ball …

Seriously pull the drive train you have and check the structure of the boat before getting into it . Sight unseen I would put money on stringers and transom rot. Of course these can be fixed but it’s **** work to do
Click to expand...
The stringers and transom are good, the boat was from my grandpa which has been stored properly and has been stored into a shed its whole life. I'm just trying to build a boat that you wouldn't see everyday.
 
SILVERLINEv8 said:
The stringers and transom are good, the boat was from my grandpa which has been stored properly and has been stored into a shed its whole life. I'm just trying to build a boat that you wouldn't see everyday.
Click to expand...
Your best bet is to find a complete tear out or buy a boat with rotten stringers and interior , junk the rest once you pull the power train.

Yes a gen one can be used, parts are still available, just keep in mind that the transition to gen 2 was in 1991.
 
Ayuh,...... Dieter is right on,...... Look for a rotten boat, with a 350, Alpha drive,.....

A BBC needs a Bravo drive,...... The combined weight will be more than you want in a 17' boat,....
 
Back
Top