omc cobra to bravo 1 swap

[chad eppig]

I know this subject has been talked about alot on sites and i have seen posts about it but I am really curious to see if any of you guys out there have any personal knowledge of this swap and how it goes? Also i have center riser log style manifolds with 4 in thru hull exhaust so is there any reason i can use those manifolds still? It seems to me i just need to change the drive and add the engine ran raw water pump for the bravo drive am i correct? Not trying to be cheap and half *** just simplicity mainly. any input would be great thanks guys.;

 

[Bondo]

I know this subject has been talked about alot on sites and i have seen posts about it but I am really curious to see if any of you guys out there have any personal knowledge of this swap and how it goes? Also i have center riser log style manifolds with 4 in thru hull exhaust so is there any reason i can use those manifolds still? It seems to me i just need to change the drive and add the engine ran raw water pump for the bravo drive am i correct? Not trying to be cheap and half *** just simplicity mainly. any input would be great thanks guys.;

Ayuh,.... Welcome Aboard,... What motor are ya startin' with,..??

Ya still need the Mercruiser stuff to mount yer OMC dressed motor to a Merc drive,.....

The Only commonality 'tween the OMC, 'n the Merc is the transom hole, which will still probably need some "Tunin' "...

Rick did a 460 OMC King Cobra, to 454 Bravo III swap a few years ago,...
I'm sure he'll be along shortly,....

 

[alldodge]

I know this subject has been talked about alot on sites and i have seen posts about it but I am really curious to see if any of you guys out there have any personal knowledge of this swap and how it goes? Also i have center riser log style manifolds with 4 in thru hull exhaust so is there any reason i can use those manifolds still? It seems to me i just need to change the drive and add the engine ran raw water pump for the bravo drive am i correct? Not trying to be cheap and half *** just simplicity mainly. any input would be great thanks guys.;

Don't know about the drive swap but seams you would only need a different length of hose for through hull exhaust. Need to install a exhaust block off plate on the transom assembly and remove the exhaust boot/tube going to the bellows.

 

[bruceb58]

For the least complicated fit, would be best to have the Merc style manifolds since you will be mating up with the Merc tube going to the drive.

Personally, if the Cobra is working, just keep what you have and keep it running. Why do you want to switch?

 

[HT32BSX115]

Hey! Happy New year Bill and Bruce!!

Any of you guys out there have any personal knowledge of this swap and how it goes?

Yes. It was fairly easy. but I swapped a complete Cobra 460/thru-hull for a Bravo 454/y-pipe/thru-prop. I did not use ANYTHING OMG/Kobra with the "new" engine and drive.

Also i have center riser log style manifolds with 4 in thru hull exhaust so is there any reason i can use those manifolds still?

Depending on the engine you have, you may be able to match up the logs with the thru-hulls.

It seems to me i just need to change the drive and add the engine ran raw water pump for the bravo drive am i correct?
Not trying to be cheap and half *** just simplicity mainly. any input would be great thanks guys.

Sounds like you want to use the same engine.....Which I'll guess is an SBC?

Understand that you MUST use the Mercruiser Bravo gimbal mount, and all Mercruiser engine mounting accy's
(inner transom-plate, flywheel housing, engine mounts, trim pump etc.

You MAY be able to use the OMC alternator mount, and other belted accessories but then you'll need to either adapt the raw water pump or use a Volvo raw water pump etc..........

Since the Bravo throttle/shift mechanism mounts to the starboard manifold, you'd need to adapt the mounting to the OMC manifold.

It could be done but you'd have quite a "Franken" engine once it was all together. My choice would be to use Mercruiser manifolds and risers.

It also may be very hard (or impossible) to adapt the Bravo raw water pump if you don't use mercruiser pulleys, damper, alternator mount, water pump (pulley) etc....... (alignment)

A good way to go would be to find a complete (maybe freeze damaged) Mercruiser Bravo (equipped) engine and swap all the "stuff" over to yours.

The "Best" way to go is to find a COMPLETE engine/drive combination to buy either outright or from a damaged boat etc.......... That way you'll have nearly everything without needing to scrounge!

When I did mine, I found a complete 1997 7.4L Bravo III combination from a damaged boat on Craigslist. While I was looking, I also found several SBC/BBC Bravo packages in various years and hours etc.....

Cheers,


Rick

 

[chad eppig]

Thanks guys you reply so fast! answer bondos question. Currently i have the original 1988 350 chevy omc block. I have vortec heads on it and a marine cam to match them along with the edlebroc vortec intake and a q jet carb. The reason i want to swap the cobra out is mainly strength.So i want a drive that is reliable and strong that they still make parts for readily and available. The bravo 1 seems to me as the best choice. But im not a boat mechanic by trade so thats why im here talking to the knowledge. To add to that, If i were to go with this swap i would most likely look for a 454 merc setup. But maybe im over thinking the cobra and its not as weak as i think? I am running about 285-290 hp now and i dont drive it hard or slam the throttle from a stop aside from occasionally pulling a wake board.

 

[chad eppig]

Rick just saw your reply after i wrote my last one, thanks for the info, my ultimate choice is going to be finding exactly what you did and run a bbc. personally i dont think small blocks work well in boats especially heavy ones. Mine has the hp but lacks the bb cubes for torque out of the hole. I will start combing cl and see what i can find. It is a bit slim up here in washington for some reason. Again i was only asking for the short or easy way because i didnt know what similaritys are there between the two drives. But i will be doing whatever i do the right way whatever it may take. no frankenstein engines here lol

 

[HT32BSX115]

Howdy Chad!

I found them all in the Seattle/Tacoma Craigslist over several months time!

Right after I got the 454/Bravo III combo, I found a 2004 (I think) 496 Bravo III with only about 80hrs on it for an asking price of $8000 or 8500. . I suspect they would have taken maybe $7000-7500 but I had already gotten the 454.

What kind of boat are you wanting to put it in?

 

[Faztbullet]

Easier to install A SEI conversion kit and slap a Alpa unit on it ...

 

[bruceb58]

I would keep the Cobra if you are keeping that engine.

 

[Lou C]

If the Cobra you have is in good shape and the cable/shift linkage has been in good adjustment, there is no reason to swap out the Cobra, with a Chevy 5.7 power plant. The Cobra is plenty strong for that application. If you were completely repowering the boat to a big block Chevy then I could see you wanting to switch to a Bravo. If you can't find a donor boat and buy the whole package this is going to be expensive. The Cobra is more than strong enough for a normal small block.

 

[chad eppig]

Ok, thanks for all the information everyone. Im going to take the advice and repair the cobra and continue to run it.