Replacing 351W with 350 Questions

Before I start, let me say I don't want to start any Ford/Chevy loyalty discussion; just looking for the facts.
I have a tired 351W (right rotation) that I am considering replacing with a Mercruiser MPI 300HP 350 with FWC. It has 255 hours on it and the boat it was in was in a traffic accident while being trailered. I know I would need to rotate the tranny ring for the left rotation, get a different engine/tranny adapter, and get a LH prop, but wondering what other costs or problems this might entail. The engine I can get for $700, so at this point it seems that the parts to convert, along with the engine would be less that redoing the current RWC 351W. Anyone who did this? What other problems / issues came up? This is for a Fish Nautique, by the way. Thanks!!

From the Velvet drive manual;
"IT SHOULD BE REALIZED THAT THAT INDEXING THE PUMP FOR OPPOSITE ROTATION DOES NOT CAUSE OUTPUT SHAFT ROTATION TO BE REVERSED, but it does permit the transmission to be used behind an opposite rotating engine."

So at least you won't need to buy a new prop.

Hi Fishy
I think you are under the right impression and Bob's 2001 is not quite right

If you put in a LH engine, you have to reorient the pump and use a LH propeller.

If you tried to use a LH engine with the pump set up for a RH rotation you will have a boat that runs in neutral and nothing else.

The 1:1 rotates the same direction as the engine and can't be made to rotate the opposite of your engine rotation (unless you slap it into reverse)

You will need a new LH prop

KENO

Hey Bob
I'm just going on experience, it won't work.I've tried it.

The way I read what you have quoted, it says that you can reindex your pump so that the same transmission can be used behind either a LH or RH engine. The middle part of the quote says that "it does not cause output shaft rotation to be reversed"

The last part says it permits the transmission to be used behind an opposite rotating engine.

So you can take that transmission from a RH engine reorient it and have it work behind the LH engine, but it will turn the same direction as the engine.

Wouldn't things be a lot easier if you could reverse the direction of shaft rotation. We'd all be happier not having to deal with these RH rotation engines.

KENO

I also have a std rotation engine in a boat that was originally reverse rotation. The pump was indexed to match the direction of the input shaft and a new opposite rotation propeller was used. The 1:1 transmissions always turn the direction of the input in forward and the opposite direction in reverse or they don't turn at all. So if you change the direction of the engine you need to change the pump orientation and you need to buy a new prop. Bob is just a little confused about the implications of the statement "IT SHOULD BE REALIZED THAT THAT INDEXING THE PUMP FOR OPPOSITE ROTATION DOES NOT CAUSE OUTPUT SHAFT ROTATION TO BE REVERSED".   It means nothing more than that the output shaft rotation will be the same as the input shaft rotation in forward gear, no matter what the direction of the pump. They say specifically that you need to run the transmission in the forward position to move the boat forward and the reverse position to move the boat backward. Page 25 of the installation manual covers matching the prop, engine, and transmission pretty extensively.
-Joe.   

Thanks everyone; I just confirmed from a local marine transmission shop that the 71c/72c 1:1 transmissions always rotate the shaft in the same direction as the engine. When used in dual counter-rotating applications, it's the engine that is made to turn in reverse. That statement in the manual is not real clear on this.

I also was concerned about the size / length of the 350 fitting into the opening in the deck. The PO appears to have cut a small (1") notch in the front of mine to be able to take off the belt, so it's a tight fit. Does anyone know if the 350 is longer or shorter than a 351? Thanks again.

Captan,
    Don't know how much difference there is, it was like this when I got it. The previous owner had replaced the original engine with a std rotation napa rebuilt engine and knew just enough to be dangerous and indexed the pump and put on a matching prop. When I got it the cheepo engine was on its way out and when I replaced it I had yet to find this forum and had no idea what way the engine rotated to begin with so I scratch built another std rotation engine.   
     Hopefully this summer up in New England I will get to experience some other similar boats that rotate the "correct" way and see if there is any significant difference in list or steering feel. You can get just about any part in either rotation, the only parts that you can safely get through automotive channels that are rotation dependent are the crankshaft/seals and camshaft, and while the automotive parts are easier and cheaper to obtain they are not so much so that it would warrant buying a new prop and starter so you could use them.
    I guess if you were talking about a built up engine the savings to go with a std rotation motor might be worth it?

KENO wrote: Hi Fishy I think you are under the right impression and Bob's 2001 is not quite right If you put in a LH engine, you have to reorient the pump and use a LH propeller. If you tried to use a LH engine with the pump set up for a RH rotation you will have a boat that runs in neutral and nothing else. The 1:1 rotates the same direction as the engine and can't be made to rotate the opposite of your engine rotation (unless you slap it into reverse) You will need a new LH prop KENO

After much perusal of the shop manual I have come to the conclusion that the trans turns same as engine. Therefore you were right and I was wrong. I thought I was wrong once before but I was mistaken. Never been lost either, just powerful confused for a while.

If you prefer RH props enough you can get a reverse transmission. My PCM tranny is a reverse type.. I have '89 with a PCM LH engine with RH prop. The model number is PLDPR-R12/PP which stands for Pleasurecraft, LH engine, 351/255HP, Pleasurecraft, Reverse, RH prop, 1.23 gear reduction, Power Plus trans.

Although I am getting used to the RH prop that I have now, I actually prefer LH props because I am used to LH props. My last boat of 7 years had a chev with a LH prop (not a correct craft). Docking was very easy because the back of the boat sucked into the dock on the drivers side when throwing it in reverse.

Let us know how the chev conversion goes, Good luck.

We had a 65 Mustang with a 260 which a PO had converted to standard (engine had RH stamp on front cover). At cruising speed with just driver it listed significantly to starboard. Finally figured out the cause, eventually installed a RR 289, problem gone. Still have this 260 if anyone's interested. Complete, good running LH longblock minus oilpan, very cheap.

I had a 69 Century Buccanner,original rh rotation 318,froze broke badly,boat sat for several years and i came across a nearly new ski centurian road wrecked,I bought this boat for cheap moved running gear to century,This was lh 351,boat did run a bit laid over but it was a deep vee hull,one good ice chest of cold beer always compensated very well.And I prefer LH rotation cause your on the right side to catch yourself when docking.I also know it to be true that reversing the pump and changing the prop is all ya need to do behind the motor.If I had the chance I would embrace a rorational directional change in any boat i had to left hand.The bad news is I'd have to build a reverse rotation motot to do this to my 92 SN

Of course all this is just my opinion,

Good Luck Munday

I have a 1986 FN , FWC 351 with the prop guard , 2600 RPM = 23 mph and fish the gulf out of Tarpon Springs , troll for grouper with down riggers , 30 miles out and troll all day burn 23 gallons. Want to go diesel someday.