Power/OutDrive Swap - 3.0L Alpha1 to 4.3L GenII

[Rick Stephens]

Howdy all,

I own a '91 with a 3L Alpha1, and it needs the motor gone through - rings, valves, that kind of stuff. Runs OK but after 25 years feeling its age.

I purchased cheap a nearly identical model boat that is a '93 with a 4.3L and a GenII. The boat is shot with severely cracked gel coat and rotted out floors.

Eng 0D623856
Tran 0D653287
Drive 0D648864

Previous owner did a motor rebuild and upgrade to Vortec heads and Edelbrock intake. Nice job of it too, although they stayed with the standard carb. (which is fine with me)

I am looking at this and wondering where the gotchas are to swapping everything over. Fit appears ok, Bluewater optioned that boat with 3L or 4.3L. The engine cover looks like no issue, although a tighter fit width wise.

1) I know I have to glass in motor mounts, doesn't seem a big deal.

2) Swap entire transom assembly.

3) Swap the steering - wheel back - the GenII has power steering and entirely different cable end.


Questions:

1) can I use the existing wiring harness from the 3.0L for the 4.3L? It has the same plug and it will reach.

2) I prefer the UFlex controls already on the older boat. Any differences using it on the GenII? The Mercruiser controls on the newer boat are missing the push button in the middle. I'd either have to fab one or do something else there.


What am I missing?


Thanks!

Rick

 

[Bondo]

Ayuh,.... Other than the motor mounts, it oughta be a plug, 'n play swap,.....

I pulled a '74 3.0l, MC-1 outa my barge, 'n dropped in 'bout the same driveline you've got,....
'bout 2,000 hours, 'n still goin' strong,....

The Merc/ Weber carb is a good tuneable solid carb,... same as the edlebrock, parts even interchange,....

The controls, 'n steerin' will probably depend on the length of the cables,....

 

[Rick Stephens]

Thanks Bondo,

Looks straight forward.... I just know how easy it would be for me to miss something obvious. Nice part is having the complete boat to scavenge from.

Now to bench run the new motor.... it's been sitting a while.

Rick

 

[thumpar]

Since that boat had the option for a 4.3l it should help with making the mounts work. Sounds like a nice upgrade.

 

[Rick Stephens]

Since that boat had the option for a 4.3l it should help with making the mounts work. Sounds like a nice upgrade.

Indeed thumpar. Structural members are identical except for the built up mount areas. A couple 2 x 6s and some fiberglass should do it.

The more I poke and measure and prod at the 4.3L/LX, the more comfortable I get that this is doable without killing my pocket. Be something to have an additional 100 HP hanging on my little 17 foot runabout.

I even have an interested buyer for the pulled 3L power and drive. The leg is a year old SEI unit.


Thanks so much to al' ya'all for bein' here. Enormous help.

Rick

 

[HT32BSX115]

That's going to work well. about 10 years ago I swapped out an OMC Cobra for a Mercruiser and never looked back AND I was able to part out all the OMG Cobra stuff for a LOT of money all totaled up over a 2 or 3 year period.

(I even still have the 2 excellent condx SS OMC props left to sell one of these days too!!.....BUT can't do that here.....classified selling is not allowed!)


Regards,


Rick

 

[Rick Stephens]

Anyone know what manual has the Rochester carburetor in it? #14 should, but it only has the Weber and the Mercarb. I checked #25 and it also has only the Weber/Mercarb.

Thanks!

Rick

 

[Rick Stephens]

Found it, #7.