Converting Alpha Gen 1 to Bravo One

[500dollar744ti]

I have a 1990 boat with a 350 magnum Alpha one. The boat is somewhat unreliable because the Alpha drive, upper unit, lower unit, or both seems to break at the most inopportune times.

I've been told that my 'heavy hand' combined with a heavy boat and powerful engine is what continues to cause the drive to break. This is not good because I like full throttle starts and I'm building a 383 stroker to replace the 350 magnum at some point.

I went and did some shopping this week, and a lot of driving. I got a 1.5 ratio Bravo One drive from a guy that lives 2 hours away, and I got the rest of the stuff from a gentleman cutting up a boat in PA. It all cost me $1600 and 10 hours of driving total.

I THINK I have most of what I need here except for the flywheel cover and seawater pump and bracket. Can you all let me know what else I might need so I can prepare for this swap accordingly?

Also, what is that white garbage on the back of the gimbal housing? It that a sealer that is supposed to be applied when installing even though there's already a rubber seal?

 

[thumpar]

You will need to add a seawater pump to your engine because the bravo doesn't have one in the drive like the alpha. You also will need to remove the shift interrupt. There is probably a lot more but those come to mind first.

 

[Fun Times]

In case you wanted to be sure of the year, your transom assembly serial number 0K207743 makes it model number 6020000KT which makes it a 1997 unit....Here's your parts catalog for it if needed. http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809808+96

Post the serial number of the stern drive if you'd like some info about it such as year, etc.

The white stuff looks like someone put something such as 3M 4200 marine adhesive sealant on it for added leak protection. Mercruiser says to install the transom assembly dry and most boat manufacturers install it dry but some service techs will occasionally add sealant successfully. I would recommended installing a new rubber seal whether you add sealant or not.

Also it looks like the inlet water fitting is not installed and it looks like there was a start of corrosion buildup happening at/behind the fitting item numbers 20 - 23 in the following link, http://www.mercruiserparts.com/Show...8.png&inbr=1943&bnbr=160&bdesc=GIMBAL+HOUSING

^ The alpha water inlet is a different design & size vs the bravo fitting so you'll need one for the bravo if you don't have that already.

^^ You'll want to clean the water inlet area up and you may need the water hose insert tool merc part number 91-43579 to remove/install a new plastic fitting in that area. http://www.bing.com/images/search?q...=QBIR&pq=91-43579&sc=3-8&sp=3&qs=AS&sk=MF1AS1

http://www.amarket.com/BRAVOblock.htm

 

[500dollar744ti]

^^^ thanks for the great info. Is there a place I can find the drive serial number?

Also, what is it about the shift interrupter? I don't know anything about these bravo drives. Would I just remove the interrupter and then shift as I normally would once the cable is connected?

 

[45Auto]

Do you see the corrosion in your water passage circled in red below? it's a VERY common problem in Bravos and the restricted water flow will cause you over heating problems.

Do yourself a favor and fix it forever while you can easily get to it with one of the Hardin kits below. Otherwise you'll end up pulling the engine again to fix it later.

http://www.hardin-marine.com/p-74054...epair-kit.aspx

 

[Fun Times]

The drive serial number should be/normally be found on the side of the upper unit on or under the sticker...See if this helps any, Where to Find Mercruiser Stern Drive and Engine serial numbers.
Drive units
In-line Engines
V6/V8 Engines

 

[thumpar]

^^^ thanks for the great info. Is there a place I can find the drive serial number?

Also, what is it about the shift interrupter? I don't know anything about these bravo drives. Would I just remove the interrupter and then shift as I normally would once the cable is connected?

You can just remove the shift interrupt. Bravos don't have the clutch dogs that lock so they don't need the stumble to get our of gear.