Bravo engine to alpha boat
 

Hi everyone, I am new to the forum.

I own a 2004 frankenstein Sea Ray 185 sport, which I purchased sunk and got running on an older late 80's V6 4.3L using the same Alpha 1 gen II outdrive. To make a long story short, on the last repair the mechanic left the temp and oil pressure gauges and alarm disconnected, I got an oil leak and now the engine is knocking. On top of all this, the boat is in southern Chile, where it is almost impossible to get replacement parts. This being said, I found a 1998 5.0L V8 which came out running of a boat with a Bravo outdrive. This seems like the best alternative, considering I can get the 5.0L engine for $1,200 USD. I am not looking for performance, rather a cost efficient repair. From what I've read here, apparently the swap can be done but I need some help from the experts.

- The engine mounts are further apart in the V8 than in the V6, does anyone know of a kit or would I have to resort to my mechanic's creativity?
- The new to me 5.0 has a raw water pump. Which is the best way to go with the water pickup, thru-hull or transom mounted? What to do with the impeller in the alpha drive?
- My 4.3L has a working Thunderbolt IV ignition module, the module originally on the 5.0L was used on its replacement and I won't be getting it, so I need to get one. Will the 4.3L V6 module work with the V8 5.0L setup? If the answer is yes, does anything else need to be done in addition to setting the timing? If no, should I aim for a TB IV or TB V used? Are there alternatives to purchase new?
- Are any other adapters needed in order to setup the 5.0L engine? I.E. cable terminals, additional harnesses, etc.
- The alpha outdrive most likely has the V6 gear ratio, is it possible to adjust in the meantime with the propeller pitch until I can get a new upper section with the 1.62 ratio?

I appreciate everyone's help on this, I look forward to carrying out the project successfully and take some pictures along the way for the forum users.


Best regards,


Pablo

The mounts should be close to the same going from a 4.3 to a 5.0. All you have to change is the bell housing on the back of the engine....unbolt it from your 4.3 and bolt it on the 5.0 and put it in. The water pump you won't need because it's in the drive on an alpha which you know from the sounds of it so all you have to do it remove the bravo style pump on the engine. Not sure on all the ignition stuff.

Unless this is a 5.0 ford which is unlikely...if it is then everything will be different.

Just for reference...your 4.3 is the exact same as a GM 5.0 with 2 cylinder lopped off.

Good luck!

Is the alhpa coupler different ? thought the center section was smaller....

Mounts will be safe width but the 5.0 mounts will be shorter because they don’t have the big vibration absorbing rubber sections. I used some bigger aluminum angle and through bolted them to the stingers.

Remove the engine mounted sea water pump and use the drive pump.

Just make sure you check timing at full advance and set it to that. Don’t worry about idle timing.

Just go up in pitch. Use the old shift linkage and set up the shift interrupt that’s on it.

Bellhousing and coupler will both work but I would use the 5.0 coupler if possible. As I think about it bell housing may be different if it is a newer engine. Not sure on the years though. Engine harness cannon plug may need an adaptor depending on year of engine also.

Years ago I put a 350 in place of a 4.3 in a Astro Mini van. Pretty sure the engine mounts were further forward on the 350, don't remember how much thinking a couple of inches.
Probably get away with just going up in pitch on the prop. Don't think there was that much difference between the 4.3 and 5.0 hp.

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yep it’s different

I replaced a 4.3 with a 383 in my old 16 classic years ago. If memory serves me correct , it was a little shy of 3 inches forward on the engine mounts. I didn’t convert to a bravo fwiw.