3.0 to 5.7 swap

R

Ripcurl7278

Cadet
Joined
May 12, 2011
Messages
13
I bought a 19 foot bowriver with a 3.0 knowing id have to replace the motor because it was shot. i have a few months to work on it until its warm and want to do a swap to a 5.7 DROP IN. not worried aout the time and money im fine with that. i just want to know if anyone has the motor mount spacing or placement or a layout for the front motor mounts so i know how to check if i can cut and fiberglass to make this work. thi would be a great help. thanks, steve.
 
matt167

matt167

Captain
Joined
Sep 27, 2012
Messages
3,690
Re: 3.0 to 5.7 swap

your best bet is to wait and do the modification when you get a motor. You will need a new transom plate and leg among other things ( entire new engine/ drive ), so a rotted donor boat could give you the dimensions and drive system you need
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,022
Re: 3.0 to 5.7 swap

Ripcurl7278 your other post was deleted. You only need to post your question one time and not multiple times in other sections.

Thank you.

Yes, you will need to have a complete donor set up .....it is not a drop in at all and you might have to do some structural work to support the new motor. Absolutely not an easy "drop in" job.
 
thumpar

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: 3.0 to 5.7 swap

You are better off just buying a boat with the engine you want to start with.
 
tazrig

tazrig

Lieutenant Commander
Joined
Dec 20, 2012
Messages
1,752
Re: 3.0 to 5.7 swap

How heavy is the boat? a 5.7L in a light (2,000 lbs.) boat is a lot of ponies... are you sure you can almost double the engine safely??
 
Howard Sterndrive

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: 3.0 to 5.7 swap

I went from a 3.0 to a chev V6 in my boat and I didn't have to do anything to the transom assembly. All chevy engines in boats have the same rear bolt pattern so the 3.0 flywheel cover will swap onto a V8.
I just removed the 3l exhaust pipe and fitted a Y pipe.
The drive itself will have to change for gear ratio - at least the upper half. the lowers are all the same as long as all same generation
 
M

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: 3.0 to 5.7 swap

If not worried about the money then it shouldn't matter what boat you spend it on, like another one with a V8 that already runs :confused:
 
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