Mercruiser engine and outdrive replacement - keyhole size

[pckeen]

I'm looking at a 1974 boat with a Mercruiser engine and outdrive. The existing motor was run with dirt in the gas tank, and has now sat for 10 years. If I pick this up, I will want to put in a much newer (2009 or newer) Mercruiser 5.7 and Alpha One/Two or Bravo outdrive. My question is: Is the keyhole in the transom the same for a modern Mercruiser and outdrive?

Any advice on what to look for or consider when considering a replacement like this would be appreciated. I don't know....what I don't know. This would be part of a complete boat rebuild.

Here's a pic of the engine and outdrive as is.

 

[thumpar]

Re: Mercruiser engine and outdrive replacement - keyhole size

They keyhole is the same but I think the Bravo has either an extra or one less hole. For 2009 you are going to need everything from pulley to prop. It would be cheaper to just buy the boat you want with working engine/drive.

 

[achris]

Re: Mercruiser engine and outdrive replacement - keyhole size

The cutout is the same for Bravo and Alpha One Gen II. There may be a slight modification required from earlier MC-1 drives. It's just a slight widening in the middle, a relocation of a couple of the middle holes and drilling of 2 new holes at the top. It's really quite simple...

 

[pckeen]

Re: Mercruiser engine and outdrive replacement - keyhole size

They keyhole is the same but I think the Bravo has either an extra or one less hole.

The cutout is the same for Bravo and Alpha One Gen II. There may be a slight modification required from earlier MC-1 drives. It's just a slight widening in the middle, a relocation of a couple of the middle holes and drilling of 2 new holes at the top. It's really quite simple...

Thanks - that's what I needed to know!

For 2009 you are going to need everything from pulley to prop. It would be cheaper to just buy the boat you want with working engine/drive.

I'm looking to do a total restore on a 70's aluminum cruiser.....even if I got one with a running motor, I would still want to replace it.....I want something that is truly turn-key, with no worries (no B.O.A.Thousand jokes now).

 

[thumpar]

Re: Mercruiser engine and outdrive replacement - keyhole size

OK. I see what you want to do now. Unless you are going 350 mag or bigger I would stick with an Alpha. The Bravos can be spendy and you don't need it unless you really want the dual prop Bravo 3.

 

[Watermann]

Re: Mercruiser engine and outdrive replacement - keyhole size

Peter it's no big deal at all to covert your keyhole from an older style MC to a newer Alpha or Bravo. I had to plug 2 holes and then drill in 2 new ones to convert my 1970 MC equipped transom to Alpha One. I also had to cut out the keyhole to of a more bowling ball shape for the Alpha. It took about 15 minutes is all. Having a donor boat as a template is what made it so easy.

 

[pckeen]

Re: Mercruiser engine and outdrive replacement - keyhole size

Now I've just got to get the seller to return my call....

 

[Watermann]

Re: Mercruiser engine and outdrive replacement - keyhole size

Any word yet?