89 460 king cobra to 86 Volvo 290?

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mpolt81

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My 460 died and I think the out drive is close behind. I have a 1989 28ft command bridge and found a 1986 28ft command bridge for near free. Am I crazy for thinking I could put the Volvo 290B DP in place of my 460 KC? My KC is in the water and only have one trailer so I can't check the bolt pattern and dimensions. My only real concerns is the transom hole dimensions and the steering... The 89 had power steering and the 86 does not. The mechanical work doesn't scare me but the transom mod does. Any help would be appreciated!
 
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Maclin

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The transom hole is way bigger for the Volvo, you could not avoid modifying the transom. But making a bigger hole is easier than filling in and starting over. I remember posts like this before, and Don S and others had some templates. I know one member here, HTB, went to a Mercruiser 454 and Bravo 3 from a KC, quite a mod but (if you can find the donor engine and drive) you end up with a very sustainable package.
 
bruceb58

bruceb58

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You sure you want to go from a 460 down to a 5.7? I would be looking for a 454 chevy setup in either a Merc or a Volvo SX style if you are going to go through all the trouble.
 
jerryjerry05

jerryjerry05

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Doubt you'd be happy with the 5.7 after the BBF.
You sure it's a 290 drive? Pics?
The Volvo drive will handle a BB if you manage to find one.
Not gonna be cheap either.
Not gonna be easy at all.
 
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mpolt81

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No I am not sure it's a 290. I'll post some pics when I get home. I'm not even sure it's a 5.7 but it is a SBC and in a 28 foot bay liner it couldn't be a 5.0 or 4.7. I was told a 5.7 with a DP would be sufficient for power but Google says a lot of things. This is just a family cruiser for fishing, tubeing, and swimming so efficiency is more important than power as long as it can cruise smooth. I could just rebuild my 7.5 KC but stumbled across this boat and has other interior stuff I need too. KC parts are getting harder to find so I would rather go to a BBC with a merc but the price is right. Just wondering the opinion of the pro's. Is it worth the work or keep looking?
 
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Maclin

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Mpolt, I agree with the others on the power. The main reason I suggested the 454 Merc mod is for the power that a 5.7 will NOT have to push you along.
 
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Jeff Norton

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I chose this forum at random. I have a question about my 2000 Mercury Outboard 90HP motor and I can't figure out how to start a new thread in this forum. Please help me get situated. Thanks, Jeff Norton

Engine runs ruff and smokes at slow speeds with motor trimmed all the way down. When I trim the motor up it runs fine. Trimmed down, BAD - Trimmed up, GOOD. Any ideas?
 
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Maclin

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Jeff, I have an idea on your issue, but keep in mind I am not an outboard mechanic and have limited experience. Many outboards have mercury (not related to the brand) switches that only allow spark when within a range of angles, this is to keep from starting with engine tilted all the way up, like when trailering. Not sure if yours has this feature or not, but you will find a LOT of help in the Mercury and Mariner Outboards section.
 
bruceb58

bruceb58

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We had a 5.7L in a 27' Bayliner. It was a major dog. Only advantage you have is the duo-prop.
 
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mpolt81

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I found a possible candidate for the swap. Owner states it is a 1982 bayliner 28ft sunbridge 460 mercruiser with a "new" alpha outdive for cheap. Too far away to go take a look and see if it will match up. Anyone familiar with this setup?
 
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Maclin

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Definitely not an Alpha with the big block, especially with that kind of load it will feel.
 
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Maclin

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Just sayin' 27' to 28' is where the builders start installing twin engines.
 
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HT32BSX115

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mpolt81 said:
I found a possible candidate for the swap. Owner states it is a 1982 bayliner 28ft sunbridge 460 mercruiser with a "new" alpha outdive for cheap. Too far away to go take a look and see if it will match up. Anyone familiar with this setup?
Click to expand...

Howdy,


That is not going to be an Alpha if it's another 460 unless someone somehow cobbled an SEI "conversion" to the King Cobra transom. And like the others above, I wouldn't put an Alpha behind any BigBlock!

Back in 2005, I removed the 460 King Kobra from my 87 Four Winns Liberator and installed a complete 1997 454/Bravo III I found on Craigslist. I looked for a Volvo BBC/DPS but found none. I did find more than a few Mercruiser 454/496 + Bravo III setups and one (2004) 300HP 5.7L MAG + Bravo I for $7500.

I was in the process of making the guy another offer since he turned down my $6000 offer when I found the (120hrs since new) 1997 7.4L + Bravo III for $5000.

With boat as big as yours I would not put anything other than a Merc/Volvo 454 + Bravo III or Volvo Duoprop drive. It'll be a real dog with anything smaller.

Unless you want to re-do your transom, you'll need to stick with either a Bravo or newer Volvo SX/DPS etc type drive.


Regards,


Rick
 
jerryjerry05

jerryjerry05

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They sold the BB with the Alpha. Special gear ratio.1.32-1
I repaired one for a guy for 2 years until he sold it.
30ft. Donzi twin BB with Alpha
Jasper rebuilt the drives 2 different times.
Once it made it about 1/2 mile.
They suggested not to "race or run it hard" wouldn't last.
The 5.7 with the Duo prop would be acceptable. Just barely but would work.
The Volvo drive can handle anything you put in front of it.
They have been hooked up to a 500hp diesel.
 
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