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Alpha to Bravo

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18Warrior

Contributing Member
Is it possible to change an Alpha outdrive to a Bravo outdrive? Looking at a 20' Chris Craft with a 454 and an Alpha outdrive, but not too sure about the Alpha holding up?
 
In order to use a Bravo you need the entire Bravo transom assembly (inside and outside).
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The shifting and bellhousing is completely different.

So the answer is NO its not a simple outdrive swap.
 
Thanks, that's all I needed to hear. What's your opinion on the Alpha drive behind a 454? Will it hold up? Pardon my ignorance, but I've never had an I/O. I'm an outboard guy.
 
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It can hold up if driven like an old lady only. First would be to identify if the upper gear case has heavy duty gear set. If not it will fail quicker.

No hole shots, easy throttle only to get on plane.

If a smaller light boat it may last a while but tender use only!
 
Nope, that won't do for me. It's on a 21' Chris Craft, and I drive the piss out of my boats. Thanks for the heads up. It's too bad, it's a beautiful little cuddy cabin, and I imagine quite heavy.
 
18Warrior said:
Nope, that won't do for me. It's on a 21' Chris Craft, and I drive the piss out of my boats. Thanks for the heads up. It's too bad, it's a beautiful little cuddy cabin, and I imagine quite heavy.
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You can drive the piss out of your boats but it's the same as driving a '60s muscle car fast on OEM tires and brakes- how will you stop it when you need to?

It might be heavy, but it could be a very inefficient hull, too. Small boats shouldn't need a big block.
 
It may be longer lasting in a 20 ft hull than a bigger one. Merc only offered the alpha with a 454 for a few years and had issues. When the bravo was released this was a moot point.

using the muscle car analogy- its like having small rear tires. if there isnt as much load hooking up may be ok. Unless someone swapped this in this has to be an 80's vintage boat so its lasted this long.
 
Dieter said:
It may be longer lasting in a 20 ft hull than a bigger one. Merc only offered the alpha with a 454 for a few years and had issues. When the bravo was released this was a moot point.

using the muscle car analogy- its like having small rear tires. if there isnt as much load hooking up may be ok. Unless someone swapped this in this has to be an 80's vintage boat so its lasted this long.
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But the previous owner may have avoided hammering it, too.
 
Supposedly it's a 70 mph boat, 80 mph with a higher pitched prop. And sorry, it's a 23 footer, 1988
 

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jimn said:
But the previous owner may have avoided hammering it, too.
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yes but better chance in a smaller boat.

On the iboats forum there was a post a year or two ago with a guy with a 24 ft bayliner 350 vortec (300 hp) and alpha gen 2 was going through outdrives. Similar HP to an older 454 ( I think were 300-330 hp but certainly more TQ) but boat seems just too big for that drive.

Bottom line if you really like the boat might not discount it and see how it goes or negotiate down on price.
 
If thats a stock engine it may do 60. 23 ft cuddy and an older chris craft is a fairly heavy boat.

I drove a 23 checkmate, low profile and light boat with a 454 and an alpha, back in the early 90's after servicing it.

It did 73 mph

A chriscraft 23 cuddy..... not likely

We also sold a brand, cant remember now but it was a 22 cuddy with a 454 and Bravo, that did 70
 
kghost said:
If thats a stock engine it may do 60. 23 ft cuddy and an older chris craft is a fairly heavy boat.

I drove a 23 checkmate, low profile and light boat with a 454 and an alpha, back in the early 90's after servicing it.

It did 73 mph

A chriscraft 23 cuddy..... not likely

We also sold a brand, cant remember now but it was a 22 cuddy with a 454 and Bravo, that did 70
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Yeah, he seems rather optimistic about the top speed... I run an 18' Pad V Charger SK, light boat, with a 225 OMC on it, best speed I've ever gotten is 83 on GPS.
 
jimn said:
You can drive the piss out of your boats but it's the same as driving a '60s muscle car fast on OEM tires and brakes- how will you stop it when you need to?

It might be heavy, but it could be a very inefficient hull, too. Small boats shouldn't need a big block.
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I run with a group called Fast Boats Canada, and I run one of the slower boats at 80 mph. I have a lot of experience with these guys.
 
The 454 Magnun Alpha 1 (330 hp) was an 87/88 item, factory 1:32R. I had one in an 88 SeaRay 230 Weekender. I believe MerCruiser only offered it in 87 but mine was SeaRay branded & they offered it in 88 too. The 370 hp 454 was never factory mated to an Alpha.

17 pitch Mirage & it did 54 MPH on a cool dense air day. It would also turn a 19 pitch Black Max prop, same top RPM & speed. Much better hole shot & a bit lower RPM to stay on plane with the Mirage.

The drive did OK but I never ran it hard. Didn't need to get into the secondaries to plane out unless I had a heavy load.

I don't believe you will see 60, no way 70 MPH!

So full throttle hole shots & jumping big wakes where the prop would leave the water are not its friend.
 
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