"Vasilly;
You could sure make
"Vasilly;
You could sure make the swap if you wanted to. Pay attention to the max hp rating on the manufacturer's data plate in your boat. You should not exceed this hp, as your insurance company could take a walk in the event of an otherwise legit claim.
Just this spring I swapped my 4.3 out for a small block 6.2 MAG MPI in my 1996 20 ft Blue Water Mirage. It was not cheap, but what the heck.
The 6.2 is rated at 350 crank hp, whereas the 4.3 was rated at 180 hp; so a big difference.
I changed the Alpha II 1.81 upper drive for a 1.47 that I bought on ebay, and bolted it up to the original lower gear case, with a new water pump naturally. Works just fine. I then sold my 1.81 upper unit on ebay. A fellow down in Boulder, Colorado bought it and it is working great for him.
The 6.2 runs great although I am still breaking it in. Very happy so far.
The 6.2 came with a Bravo bellhousing, which bolted right up to my Alpha transom plate. The Alpha driveshaft splines are the same as the Bravo and fit right into the Bravo coupler.
The original exhaust Y pipe would have fit just fine except I went with Hardin side hull exhaust tips instead. I wanted to use Silent Choice exhaust selectors, but the fiberglass cowling behind the engine is too close, and they just would not fit in.
The front motor mounts had to be moved ahead about 4" on the stringers. Drilled new holes and filled the old ones. No problem. My engine bay had plenty of room in front of the 4.3, as the Mirage was originally offered with a 350 MPI engine option.
The 6.2 is about 5" longer than the 4.3. Both the 4.3 and the 6.2 engines are the same width to the outside of the manifolds.
The 6.2 is about 1.5 inches higher to the top of the flame arrestor cover, and I had to modify the engine compartment cover slightly to suit.
The 6.2 came with a standard Merc 10 pin electrical connector, which fit right up to the boat connector. All gauges work fine, except my alarm buzzer for some reason.
I had to reset the selector on the back of my tach from 6 to 8 cylinder, no big deal.
As far as weight goes, I figure I did not gain more than 100 lbs net. I can't notice that the boat sits any lower in the water than before.
All in all a great swap. Any small block GM V-8 will work as a replacement for the 4.3. The 5.0, 5.7, and 6.2 are in fact all the same Gen I GM block, with different bores and strokes, heads, cams, etc. The 4.3 is actually the same block as the 5.7; with two center cylinders missing. Same bore and stroke.
If you decide to do this, my suggestion would be nothing smaller than a 5.7 carbed or MPI, with Vortec heads. Might as well get the best bang for your buck.
E-mail me if you would like some PIX of the 6.2 engine in my boat.
Hope that helps,
Rod"
