To have "shaking" noticeable in the boat indicates a relatively significant mass is out of balance. I am not familiar with Alphas...all my experience has been with Bravo outdrives and the rare Yamaha HydraDrive. Assuming you greased the u-joints whilst you had them out? You say they "felt...
are you SURE they are 1/4" pipe thread? I ask because I know Mercruiser is NOT, it is 1/2-13 standard thread...the plugs have a 'flat' on the face and use a rubber washer...
If the FSM says three, then it's three. I've personally never liked these more "modern" systems, ESPECIALLY the ridiculous 'single point drain'. For peace of mind when winterizing, simply fill the whole thing up with about 4 gallons of antifreeze. Make sure if you use the "pink stuff" it is...
When was it last "good", e.g. NOT leaking/creating the mess? Is this a new thing? One suspects a front seal but as others have noted, you need to better isolate the source/area of the contamination.
You never said but...how did the boat run? You mentioned that the 800 cfm carb was "too big"; this implies performance issues of some sort? But yeah, ditch those spacers. Go run the boat with the carb "as is", do a nice, long WOT run and then shut it down, let it cool down some and pull a...
ANY auto supply store can get you a set of wires for your BBC...basically they are all made up of a set of two pairs of 4 lengths...short, not-so-short, medium, and long. And NGK UR4 will work in pretty much ANY BBC engine.
What outdrive ratio? The Alpha One Gen II outdrive for the 4.3 LX was typically 1.81:1. You don't have a whole lot of ponies available so you need to get baseline numbers as many people have already said. You need to be able to hit your rev limiter/or max recommended rpm...assuming 4600 in...
As you note...it is a very important part...and some would say, why take a chance? My thought would be it never had a chance to "take a set" so you should be fine.
Wholesale Marine, BoatCarpet.com, Great Lakes Skipper, Custom Marine Carpet...are many good choices. Many have templates to match a specific boat model. Most offer several grades (and pricing!) to choose from.
