4.3 to 5.0 engine swapp

[Dave-R]

I just bought a 1996 19' Cobalt boat,a real beauty with a cracked 4.3 engine block. This boat is such a knockout, that instead of buying a new 4.3 longblock, I'm thinking of maybe a new 5.0. There is about a foot clearance in the front. Will the motor mounts fit or is it a drastic undertaking. It is a Volvo motor and sx outdrive. I know I would probably have to change gear ratios also. I have pulled engines before, but replaced them with the same size.
This boat is so special, I want it done right. I,ll have the motor out tomorrow, and your help will be much appreciated.
Thanks Dave

 

[oops!]

Re: 4.3 to 5.0 engine swapp

hi.....welcome to i boats !

congrats on the cobalt....i agree....they are superb boats.
im not a mechanic.....

but...

if you go to a 5.7 you are swapping for allmost the identical motor....just add two cyls....you might have to move the holes for the motor mount forward....but thats no big deal.

most every thing from the 4.3 will fit on the 5.7...(peripherals only)

i really dont think you need to change the gear ratio.....possibly just re-prop

 

[180shabah]

Re: 4.3 to 5.0 engine swapp

If you are going to do all of this work, a 5.7 would be a better option. More power than a 5.0, and identical weight and effort required for the job.

 

[wca_tim]

Re: 4.3 to 5.0 engine swapp

Second on 350 / 5.7!

 

[Dave1251]

Re: 4.3 to 5.0 engine swapp

The largest engine that Cobalt offered in 1996 190 was a fuel injected 5.0. This engine combined with a dual prop is great for the boat. I am not sure how the hull/transom would handle the extra torque of the 5.7 engine.

 

[jkust]

Re: 4.3 to 5.0 engine swapp

ok you can't talk up your boat that much without showing us some pictures.

 

[racinrc14]

Re: 4.3 to 5.0 engine swapp

Let's not forget the exhaust system. I'm unfamiliar with Volvo's, but the manifolds have to be different (and expensive to buy new) between the v6 and v8.

 

[caver95]

Re: 4.3 to 5.0 engine swapp

you can send me the old manifolds, I will take them off your hands so that is one less thing to deal with.

 

[oops!]

Re: 4.3 to 5.0 engine swapp

The largest engine that Cobalt offered in 1996 190 was a fuel injected 5.0. This engine combined with a dual prop is great for the boat. I am not sure how the hull/transom would handle the extra torque of the 5.7 engine.

you are only a 19 footer....uasually the duo props were for the bigger boats...(around 25 feet)

but as suggested....the 5.7 is a much better choice. your boat will easily handle the torque/ weight of the 350.....it will be a much easyer swap. your bell. cable harness, and electrical pig tails....everything will fit

 

[wca_tim]

Re: 4.3 to 5.0 engine swapp

You'll need about 4-5 inches more forward space at the front than you're using now and you'll have to move the engine mounts forward somewhere over 3 inches (just check to see that you've got stringer to set them on or if you have to build new structure to support the new front of the front mounts.

if it can handle a 5.0 it can handle a 5.7 - especially anything remotely stock. that's a well made boat.

Not sure what the exhaust manifold options on that are, but surely you will be able to put new ones for the v8 on and it'll bolt up at the rear if you get the right ones..

everything else should work... aside from the intake manifold and tin of course...

sounds like a nice upgrade either way. note that the boat will handle a little differently and will probably feel a little heavier in the butt end. but very likely it'll be minor - especially if you're mindful of it when you're choosing things like exhaust and intake manifolds. You can make up the hundred or so pound difference between the two engine packages to a large degree.