Change 140 merc to V8. 305

[llerrad]

Searay 20ft bowrider, Alpha 1, will the original transom and gimbal ring parts work for change out to V8 305 from the original 4 cyl 140. Will exhaust Y pipe fit up. I understand the leg will need to be changed.
Second question: when using alignment tool what is it you are bringing in to alignment? the gimbal bearing or do you adjust the engine into alignment with the bearing.

 

[Haut Medoc]

Re: Change 140 merc to V8. 305

The transom shield may work, depending on the positioning, & the boat itself, but this is basically a total repower......
The engine is adjusted to the gimbal.....
I'm sure you will get more feed back from those a little more familiar with this large an undertaking.....JK

 

[Fishermark]

Re: Change 140 merc to V8. 305

The transom assembly is the same and will work without a problem. The front motor mount will be different. A v8 has two front mounts versus the single front mount that the straight four has. The v8 front mounts will bolt to your stringers.

The Y pipe may have a different bolt patern than your transom assembly has, but it will not cause a problem. I spoke with Mercruiser about that issue and they said it is acceptable to only use the three bolts that line up if there is a difference.

So far as the gimbal bearing and alignment, you will need to "set" the gimbal bearing with the alignment tool, (hitting/tapping it sideways at ninety degree increments), and then align the engine - adjusting the front mounts up or down.