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    4.3 milky oil and water in 5 of 6 cylinders

    I have a 1990 4.3. I drained the block last fall and parked it with no further winterizing (I'm a bad person, I know). Fast forward 8 months to this weekend. I was tearing down the engine to do a vortec cylinder head swap. I removed the old heads to find standing water (and rust) in 5 of the...
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    4.3 Vortec valvetrain.

    This spring I will be upgrading my entirely stock 4.3 Merc. Seems like everyone and their mother who has a 4.3 has done this specific upgrade, but I can't find anything that answers this specifically. What I currently have: 1990 Mercruiser 4.3L 2 BBL Mercarb Non-balance shaft Non-vortec Open...
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    Boat speaker wiring puzzle

    I am trying to wire a new car stereo to my boat (Alpine stereo, 1990 Mariah bow rider). When I pulled the old stereo out, I looked at the wiring harness and it only has 8 wires (+,-, and 6 speaker wires). The odd thing is there are only 6 wires for 4 speakers. I have done some troubleshooting...
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    Why are inboards more expensive than stern drives?

    How come inboards tend to be more expensive than similarly sized and powered I/O's? It seems to me a car engine and a hull would be cheaper to design and manufacture than a car engine, hull, hydraulic tilt pump, large aluminum outdrive, and tilting gears. What is stopping a company like Bayliner...
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    4.3 Mercruiser New Wakeboarding Prop

    Looking for a new prop, primarily for wakeboarding. I would like lower plane speed, better midrange performance, better hole shot, and more stern lift/less bow lift. Stepping up to 4 blades seems to cover all of these. I am not concerned about going faster but don't want to lose much on the top...
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    Alpha One hinge pin torque

    I am installing the bell housing after a new bellows install (first time for me) and need to torque down the hinge pin bolts. I know the service manual says to torque to 95 lb-in, but (from previous experience) that seems very high for bolts this size into an aluminum housing, and I am afraid of...
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    Engine alignment after gimbal bearing install

    Hi everyone. I just replaced the gimbal bearing in my 1989 alpha one gen one. I cannot seem to get the bearing aligned. I have been using the alignment bar and this guide by Don: http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/engine-alignment-how-tos-443992.html#post2971085...
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    Engineering school project

    My team (Junior/Senior mechanical engineering undergrad students) needs to make a machine that will propel itself 10 feet in a swimming pool as fast as possible using a small 4 speed DC motor. General rules: -Must fit in a shoe box. -Must contain a 4-bar linkage (even if used to drive a...
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    Trailer jack size

    My trailer jack bit the dust last season. It seems I have a non-standard or out-dated trailer. I need a 2" OD A-frame jack. All the local shops seem to only carry bigger jacks (I believe 2.25"). Online shops don't ever seem to post this dimension, so I have no way of knowing if it is the right...
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    Bow lift, Planing speed, and number of blades.

    Heres one for the physics guys/prop Gods: I always hear and read that a 4 blade prop can hold a boat at a slower plane than an equivilent 3 blade (I'm refering to your typical 16-25 foot runabouts). I also often hear that a 4 blade will "lift" the stern more than the bow compared to an...
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    1990 2 bbl Mercarb choke

    My 2 bbl mercarb choke is not opening all the way when underway at full throttle. Is there a diagram that shows how the linkages are supposed to be? I am under the impression the throttle linkage is supposed to force the choke open no matter the engine temp when wide open. Is this right? I am...
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    Spark issue

    This was an easy problem I had that was an easy fix for anyone's future reference. I was pulling a slalom skier out of the water, WOT and RPM's at about 70% when I heard a backfire. I kept going because it only happened once. A couple of pulls later, it happened again and boat power was greatly...
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    1990 4.3L Exhaust shutter

    How do I locate and replace the Shutter (flapper) valves on a 4.3 liter Alpha One? The boat is a 1990 or a 1991 so I believe it is a Gen 1 outdrive. The boat is running sluggish and I think the valve may be stuck closed. Thanks for any help.
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    1991 4.3 not reaching WOT RPM's

    All in the title. I have had this boat (18.5 open bow) for 2 seasons, and the problem has always been there. The engine sounds just fine. It idles smooth and sounds fine at throttle. However, it is sluggish in the hole (takes a LONG time to plane, at times it does not plane). It maxes out at...
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