Mercruiser/omc set-up?

[chriscraft254]

Has anyone used a mercruiser motor and set-up with a omc outdrive with success? More specific, has anyone modified the shifting/wiring mechanisms off a omc set-up to a shift set-up from a mercruiser to work on an omc outdrive?

 

[Howard Sterndrive]

Re: Mercruiser/omc set-up?

need to be very specific with model numbers and years.
there are several completely different types of OMC drive and about a dozen Mercruiser "set-ups"... there are some combos where steering and shifting between OMC and Merc are quite similar, and other combos where they are so drastically different you would be trying to connect electrical wires to mechanical linkages or even hydraulic hoses to accomplish a union.
In general, no. Donor boats with the correct parts can usually be found cheaply enough to just do it right with less head scratching.
Professionals don't generally try to connect between bloodlines, but some DIYer has connected just about anything to anything else somewhere in the world.

 

[chriscraft254]

Re: Mercruiser/omc set-up?

Howard,thanks for the response. Its a 1990 omc cobra outdrive. Will have to look at the motor tmrw. Basically the reason I asked is. I had major issues with the omc set-up on the boat. My mechanic called it quits after burning up the 4th motor. He ordered a mercruiser motor with all the dressings. He modified the cable bracket off the omc and rewired some things. So basically from my understanding, we now are running a mercruiser shifting assembly and motor, but still retain the omc outdrive.. It has been flawless "knock on wood" since it was installed in the spring. I know just enough to get myself in trouble when it comes to mechanics, so I know this is kind of vague. But I just thought it might help some others that are tired of the troubles they have with the esa/shifting systems on the omc's. I will get some pictures and more details to share soon. All I know is it has been a dream to operate finally!

 

[bruceb58]

Re: Mercruiser/omc set-up?

Post a picture of your shifting assembly. More than likely, he used the OMC shift assembly.

 

[HT32BSX115]

Re: Mercruiser/omc set-up?

Has anyone used a mercruiser motor and set-up with a omc outdrive with success? More specific, has anyone modified the shifting/wiring mechanisms off a omc set-up to a shift set-up from a mercruiser to work on an omc outdrive?

There's generally no problem using any GM engine with a Cobra as long as the flywheel housing and other accessories will bolt
up.

Using a Mercruiser ignition interrupt (switch) in place of an OMC ESA WILL probably be a problem though. (and may not work well for long....or at all....)


OMC didn't spend a LOT of time and money developing an Electronic Shift Assist system only to be able to replace it with a simple SPST switch etc.

 

[chriscraft254]

Re: Mercruiser/omc set-up?

Used the mounting bracket and same control cables. But I beleive everything else came with the motor set-up as a mercruiser. Here are some pics. Let me know what you need pictures of or if you see something wrong other than the non-shrink style connectors that I will be replacing myself.

 

[chriscraft254]

Re: Mercruiser/omc set-up?

There's generally no problem using any GM engine with a Cobra as long as the flywheel housing and other accessories will bolt
up.

Using a Mercruiser ignition interrupt (switch) in place of an OMC ESA WILL probably be a problem though. (and may not work well for long....or at all....)


OMC didn't spend a LOT of time and money developing an Electronic Shift Assist system only to be able to replace it with a simple SPST switch etc.

I know he did away with the omc esa. The one that is on there now is the mercruiser interupter. Has worked all season. If I am aimed towards future trouble let me know. I know the motor has to be stalled on a mercruiser to change gears, and omc esa just reduces the rpm to make that happen. Where if I am correct the mercruiser shift interupter actually cuts the rmp completely for a split second. Am I correct on this?

 

[bruceb58]

Re: Mercruiser/omc set-up?

Looks good. He used the OMC shift assembly and used the mercruiser method for shift interrupt because he is using an electronic distributor.

 

[HT32BSX115]

Re: Mercruiser/omc set-up?

I know he did away with the omc esa. The one that is on there now is the mercruiser interupter. Has worked all season. If I am aimed towards future trouble let me know. I know the motor has to be stalled on a mercruiser to change gears, and omc esa just reduces the rpm to make that happen. Where if I am correct the mercruiser shift interupter actually cuts the rmp completely for a split second. Am I correct on this?

I don't see why it wouldn't work.

It has been tried in the past and some people have had problems. The OMC shift dogs aren't EXACTLY the same as the Merc dogs.

The OMC ESA doesn't just reduce RPM or momentarily interrupt ignition like the Merc switch does..... It actually "pulses" the ignition so that there are torque pulses at idle. This "unloads" the undercut shift dogs so they can be easily separated.

The ultimate goal is to reduce the torque on the dogs so you can easily pull the shift dogs apart.

If the interruption occurs when you have separation force on them (the dogs), they separate and you make it to neutral.

If the switch actuates slightly out of sync with the push or pull (on the cable) required to separate the dogs they don't separate. The ESA gives you "pulses" where the switch just gives you a single momentary interruption in ignition.

I think it could work. It just might not work every time........ if they don't separate, the engine will just quit. It's not the end of the world........