alpha-bravo swap
 

I'm sure this has been asked a few times, but what is involved with pulling a late model(2000) small block/alpha merc and upgrading to a big block/bravo ? thanks Rob

for the most part just drilling two extra holes at the top of the transom hole for the bravo mounting cutout is the same the other question is exhaust but it should also be reletively simple as long as they both had the same setup motor mounts are the same all the electrical should plug right back up if you are installing an injected BB then you may have some clearance issues with the low mount power steer pump and or fuel pump/cooler assembly but nothing that cant be overcome I have done several of the these swaps go for it you will LOVE the results !!!!

Exhaust on the big block will be farther appart.

I have done quite a bit of the conversions as well. I agree they arent nightmareish as a rule. Just add a 2 holes using a jig & mount the new transom assembly for a bravo. The worst part of the job is gutting out the power to do it.. :) Jamie

I'm new to this forum and had a question regarding conversion to Bravo....I've read many of these threads, but still not clear....I have a 1991 Mercruiser SBC with an alpha one now....I will be rebuilding it to appx 400 hp. The boat is a Donzi Classic 18. I understand I need a bravo....so what alpha parts do I need to replace to accommodate the Bravo? Thank you!

everything but the trim pump basically and you will need a bravo sea pump.

Thank you! Just checking....someone told me the alpha flywheel cover (has a 7" opening) is the same part for the Bravo.....do you agree they are interchangeable? They also indicated the alpha coupler would work too....?

In a single installation it's very easy. An option I used when I swapped twin Alphas to twin Bravos was to use a crank mounted "Raw Water Pump" and pull water thru the drives instead of the belt driven Mercruiser set up. Fewer moving parts and very easy to service.

Volvo, Indmar, Marine Power and several others use this set up.

[IMG]http://i705.photobucket.com/albums/w...psfe5cd343.jpg[/IMG]

...and you never have to worry about a water pump belt breaking!!

Great idea! What HP are you pulling from those? Are the 2-bolt main? Forged crank?

Were the flywheel covers/couplers the same between alpha & bravos?

435 at 5600 dyno as I recall w/400 + Ft Lbs TQ from 2K to a bit over 4K. These are L31 Vortec 4 bolt blocks with forged cranks. I used Bravo Full Face Couplers with Bravo Flywheel covers. Cams are Comp Roller Xtreme Marine 282*, 1.5 Comp Needle Bearing Rockers, Heads are stock Vortec with Comp Beehive Springs. Distributors and wires are DUI setup for 32* full in at 3000. I'm running Twin Bravo I's with Counter Rotating Mirage 23" props. Intakes are currently brass lined aluminum spread bore by Crusader pulling thru 850 CFM Big Block GM Q-Jets.

My boat is a 5600# Formula 255 Liberator...great dock manners, full thru prop exhaust, no reversion, Very efficient...cruises 55~60 at 3000 with 2 aboard and full tank. I've had it 78 GPS still pulling hard...but run out of "Nads" approaching 80 in a 37 year old boat LOL.

It will run 60 and below on the primaries all day. I can run from Miami/Ft. Lauderdale to Bimini...play around all weekend...and run back to Florida on about 100 Gallons...not bad.