4.3 Mercruiser vs. 4.3 Volvo penta mounts

dlogvine

Master Chief Petty Officer
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May 4, 2015
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I bought a hull of a 2004 Larson 180 sei. It had originally a 4.3 Volvo penta engine, but I'm putting in a 4.3 mercruiser. There is still original wire harness from the dash to the engine, and it has an original shifter. I have a couple questions,
1. Do the mount holes for Volvo penta engine match the mercruiser mounting holes.
2. Can I use the Volvo penta wire harness for mercruiser engine as long as I change the main connector to hook it up to the mercruiser engine harness. Do the wires have the same color matching as mercruisers?
3. Can I use the Volvo penta shifter, or should I change it also with the one made for mercruiser? If I can use it what changes should I do for the wiring?
4. And the last one is more of a decorative question, Alpha one gen 2 has speedometer pilot inside an outdrive, while on this boat it is external. Should I leave it as is or remove the external pilot, while plugging the hose to the outdrive?
thank you.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
1. Are you referring to the mounting holes on the engine block? If so, then yes, they'll be the same. Both use the same GM engine, cast in the same factory...
2. If the wiring at the instrument end comes out the same, yes. You'd have to have the harness line drawings for each to be sure.
3. If the shifter has a 3" throw, then yes. Again, check the wiring drawings to see how each maker wires the various switches (each should have a neutral safety switch and a 'deadman' switch).
4. Up to you. Although I have found the external pitot to be more accurate than the Alpha internal..

Chris............
 

Rick Stephens

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Aug 13, 2013
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I've never seen the drawings for the VP mount locations. It would surprise me greatly if the measurement to the transom plate is the same from VP to Merc. Stranger things have happened though.
 

Bondo

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4. And the last one is more of a decorative question, Alpha one gen 2 has speedometer pilot inside an outdrive, while on this boat it is external. Should I leave it as is or remove the external pilot, while plugging the hose to the outdrive?

Ayuh,..... Are you swappin', Just the motor,..??
Or the entire driveline,..??
 

Rick Stephens

Admiral
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Aug 13, 2013
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6,118
I would delete the transom mount pitot. One less place for water to get into your transom wood.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
I would delete the transom mount pitot. One less place for water to get into your transom wood.

Agree. And the free GPS apps for your phone are way more accurate, especially at low speeds, and ... free....

Chris..........
 

dlogvine

Master Chief Petty Officer
Joined
May 4, 2015
Messages
839
Ayuh,..... Are you swappin', Just the motor,..??
Or the entire driveline,..??

I bought the empty hull and am installing the whole driveline, engine, transom plate, gimbal housing, outdrive
 
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