Engine swap

[raevin51]

Hi everyone. I have a 1988 Forester 19.5 cuddy. It currently has a seized 3.0 4 cyl with a cobra out drive. I am trying to decide weather to replace the engine and drive with either of 2 options open to me. I also have a 4.3 gm engine that has been marinised wit the old style cobra out drive.The drive if I use this motor will most likely be either a volvo or mercruser still undecided on that one or I also have a 1986 Johnson 235 that was just rebuilt and only has about 10 hours on it. If I go with the outboard which is kind of where I am leaning (strictly a cost issue) does anyone make a system for mounting an outboard to a transom that was set up for an out drive or have any of you done this and what parts were needed to do the conversion

 

[crb478]

Re: Engine swap

If you patch the transom where the out drive was you can use a jack plate to mount the outboard motor on. You will want to reinforce the transom where the motor mounts, you can use comercial transom stiffeners or just a good piece of aluminum in that area. Mount the jack plate so the AV plate on the motor will be near the keel or just below at the lowest point, and then you can raise the jack plate to fine tune the setup.

If you use the 4.3 make sure that you get all of the motor mounts and brackets. You will probably have to do some fabrication to make the motor fit and you will also need to modify the transom to mount the out drive.

 

[tashasdaddy]

Re: Engine swap

i/o to outboard conversions, most people are very unhappy with the the finished project. it move the center of gravity, that the boat was designed for. poor performance. you other questions, ask in I/O forum.

 

[kaferhaus]

Re: Engine swap

My brother in law did such a conversion maybe 15yrs ago. It cost him a good bit of money and a ton of his time. the boat ended up being a handfull to steer and had a lot of yaw while planing. Took him 2 years to sell it, finally some guy bought it without water testing it...

 

[oops!]

Re: Engine swap

i/o to outboard conversions, most people are very unhappy with the the finished project. it move the center of gravity, that the boat was designed for. poor performance. you other questions, ask in I/O forum.

My brother in law did such a conversion maybe 15yrs ago. It cost him a good bit of money and a ton of his time. the boat ended up being a handfull to steer and had a lot of yaw while planing. Took him 2 years to sell it, finally some guy bought it without water testing it...

it has been done many times....(i/o to ob comversions).......i have never heard of a person that was pleased with the conversion.....in fact.....according to people here....most of the hulls were scrapped after much tryal and dissapointment.

stick with the i/o

 

[chiefalen]

Re: Engine swap

Sir; i certainly understand the desire for more hp, however to convert to a 4.3 would be in my humble opinion futile.

The engine bay will probably be not large enough to squeeze in the 4.3, the stringers for the motor mounts would have to be converted and the hp might be over the rating for the boat.

Only you know the answers to the problems i posted above.

Now to the question of the o//b being mounted to the hull of a boat originally built with a i/o transom.

You could in slap on a exterior bracket, called a gil bracket and mount the o/b to that.

My question to you would be, why ??

The simplest, and cheapest, thing to do is purchase a good running motor, 3.0 and drop it in and go.

Want a bigger motor in a boat buy one after you sell the outdated , omc boat.

Buy a boat with the hull setup for the out board, real real cheap, and install that nice outboard on it.

Just my inexpert opinion

Good luck!

 

[jaxnjil]

Re: Engine swap

I also have a 1986 Johnson 235 that was just rebuilt and only has about 10 hours on it.



older boats like this with out power can be found for not much and in some cases for hauling off.

your best and cheapest bet might be to look for a out board hull with no motor for your johnson. it sounds like a good motor.
just my thoughts

 

[Dhadley]

Re: Engine swap

Just a couple of things to consider - if the I/O to outboard conversion is done correctly it will turn out great. Many companies have sold a lot of brackets over the years for just such a project. In fact my favorite project of all time was converting a 32 Excalibur with twin 454s to triple outboard. Turned out quicker, faster, burned less fuel and had a ton more room.

Every one I've seen that didn't turn out so good was due to the outboard bracket being mounted too low. Killed the power and eventually the motor(s).

Another small point - OMC didn't make a 235 in 1986. The last 235 (crossflow) was in 1985. There is a 225 (looper) in 1986. Very different motors.

 

[DDog11]

Re: Engine swap

I would check the load capacity plate on the fuselage and the gimble housing to see if it allowed.

 

[a70eliminator]

Re: Engine swap

I would check the load capacity plate on the fuselage and the gimble housing to see if it allowed.

Boats have a hull not a fuselage