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VP260B with 290 power trim outdrive questions

Windy Bay

Contributing Member
I just purchased a 1980 25' Skipjack Sport Cruiser with a 260B engine and a 290 power trim outdrive. I have a couple of questions regarding the engine and outdrive. First the engine. When I purchased the boat the engine is in pieces and not complete. It is missing the crank, cam, flywheel, pistons and some other small parts. I have the block, heads, vibration dampner, wiring harness, alternator and raw water pump brackets. My first question is 2 part, replace the engine with a rebuilt that was a direct replacement, or go with a vortec. I know the vortec is more expensive. the rebuilder seems to think that the vortec will work with a new flywheel, intake manifold ect. the old manifold and risers are cracked, so I have to get new anyway.

second question is about the outdrive. It is a 290 power trim. I have a dp lower unit that the prop shaft Part # 872533 is grooved from fishing line. it came off a 280 outdrive on a 24' skipjack, both have 5.7L v-8, although the skipjack may have had a smaller v-8 when new. I found a used prop shaft for a reasonable amount of money, but I'm not sure the gearing would be right with the 290. any feedback would be appreciated
 
Although it's an excellent concept...... I'd forget all the Vortec stuff.
The SBC Vortec chamber and Quench surface are of little use for the Marine SBC while the GM style full dished pistons are being used.
I'd build yourself a Quench Effect SBC.
If you go with the Vortec cylinder heads.... now you can make use of the Vortec chamber quench surface, and take advantage of the torque that can be had.

See this thread beginning at post #7.
http://www.marineengine.com/boat-forum/showthread.php?394668-V6-to-V8-engine-swap

As for the 290 drive...... the final over-all gear ratio will need to be 1.61:1 in the single prop drive...... and 1.95:1 in the Duo Prop drive...... unless you build a 6.2L or 6.3L SBC.

If the prop shaft groove is not too deep..............., and if it can be polished out......, and if it doesn't prevent the seal from sealing properly during a Pressure/Vacuum leak down test........ you may get away with it.

BTW.... re; the Duo Prop drive:
The AFT propeller shaft is replaceable.
The FWD propeller shaft is not a separate component, nor replaceable.




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regarding the prop shaft, I tried to upload a photo, I believe it is the one that can be replaced it is about 18 1/2" long. I found one on ebay for what I think is a reasonable rate. I see you live in portland, I am going to use superior engine in portland to build the engine. I have had them recommended to me. I will print the information in the thread you mentioned. I tried to upload a photo of the prop shaft but to no avail. I must be doing something wrong. I live down in Elkton, OR and don't have a volvo penta dealer or really anybody down here who is good with the outdrives. know anyone in portland, seeing as how I'm going to be coming up to drop off engine jparts
 
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