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RePowering a 1980 boat

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Windy Bay

Contributing Member
I have a 1980 Skipjack project boat. The Boat has a VP 290 outdrive. I was planning on building an engine because the boat did not come with a complete engine. Instead I found a donor boat that has a 1997 DP-S duoprop outdrive with a 5.7gpsplkd engine that only has 70 hours on it. The previous owner reports that he was starting the engine about every month until about 3 years ago. the donor boat has not been registered since 99. So I believe the engine hours. Now on to my questions.

1. What is involved in swapping the outdrive? ie bigger hole for outdrive unit or an adapter plate, or something else

2 what would you do with the engine? (oh by the way fresh water cooled) Turns over using a 3/8 ratchet. I am going to replace hoses, belts and things like that. but would you pull the heads and check cylinders, valve job.

when I check outdrive serial number, and engine serial number they both come back with a delivery date of 11/16/1996.

Any help would be greatly appreciated. Tried to upload pictures but I was not able to upload them.
 
Ayuh,.... You can blow the big bucks for an adapter plate, or glass in the hole, 'n re-cut it,.....

Donno where you are, but if that motor saw any freezin' weather in the last few years, it's probably junk with a cracked block,.....
 
First off..... in my opinion Volvo Penta shot themselves in the foot when they moved away from the AQ series stern drives and designed the SX and DP-S systems (at the time of the OMC purchase).



Windy Bay said:
I have a 1980 Skipjack project boat. The Boat has a VP 290 outdrive. I was planning on building an engine because the boat did not come with a complete engine. Instead I found a donor boat that has a 1997 DP-S duoprop outdrive with a 5.7gpsplkd engine that only has 70 hours on it.
I do not know what you would be paying for this..... but I would insist on hearing this package operate.



1. What is involved in swapping the outdrive? ie bigger hole for outdrive unit or an adapter plate, or something else
The SX and/or DP-S transom unit is of a smaller foot print than that of your 1980 AQ series transom shield.

2 what would you do with the engine?

a..... I would change the flywheel to a 153 tooth, and would find a good DP-C stern drive system.

b.... I would change the flywheel to a 153 tooth, and would use it with my AQ series 290 drive.

(starter motor changes for the 153)


(oh by the way fresh water cooled)
Ah.... being fitted with a Closed Cooling system is a real plus!

Turns over using a 3/8 ratchet.
Never turn an engine over via the front crankshaft bolt!
I am going to replace hoses, belts and things like that. but would you pull the heads and check cylinders, valve job.
No....
Take cylinder pressure readings (aka compression test). If questionable, perform a cylinder "Leak-Down" test.
With the cylinder heads removed, you will have missed your opportunity for this.

when I check outdrive serial number, and engine serial number they both come back with a delivery date of 11/16/1996.

Any help would be greatly appreciated. Tried to upload pictures but I was not able to upload them.
Click to expand...


Please understand that the AQ series drives (up through 1996 in the AQ "C", "C-1", etc series) use a much better designed Main Suspension Fork and Pivot Tube geometry.
The SX and DP-S are using Gimbal System suspension geometry.

AQ series:
3 part drive components .... transmission, Intermediate housing, lower gear unit.
easy and quick transmission R&R
easy and quick drive shaft bellows replacement
all steel Borg Warner drive coupler (no rubber hub coupler as with a Gimbal system)
fixed geometry between engine and stern drive transom shield
no annual engine alignment required once installed
No Gimbal Bearing!!!!!!
No thru propeller exhaust !!!!!
larger transom shield foot print against the hull's structural transom




.


 
Rick, Thanks for the reply. I really appreciate your input and respect you opinion. I currently have a boat I have been using for years that has a 280 outdrive, and have learned through that ownership, that the older AQ series out-drives are great BUT parts are becoming increasingly difficult to acquire. One of the reasons I purchased this donor engine and out-drive is that it is a complete Package. All original parts are there and all work together. After considering your post about the drives, I looked at my 290 with fresh eyes and assessed what I would need to do to use just the engine with my current drive. I would need to get the new flywheel, Starter, Manifolds, and figure out how to connect the power steering system to the 290. Being a douprop fan, I would need to have my extra lower repaired which is mainly having the prop shaft machined. If I use the new to me package, I need to get the adapter plat ($1000.00) and install the new complete package. then I would have 2 290 out-drives that I could part out. That would most likely pay for my donor drive and engine. I really appreciate the suggestions on assessing the new to me engine. I a a fairly good mechanic, and have all tools necessary to do a compression test and if necessary a leak down test. When I turned the engine over I was just making sure that the engine was not froze. This donor package came from the coast of California so I am not worried about the engine experiencing any freezing conditions. I will do a compression test in the next few days and if all is well start the engine.

Thanks
Larry
 
Larry, it's your call. I'm just suggesting that the AQ series is a far better designed drive.
Once you experience the issues with a Gimbal suspension system, you may understand why.

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