jerosejr

Maybe everybody's right and noone has to pay the bet!!!
My info from the New Orleans bunch and JK at Runsnew is that the 71/72 series can be set to accept standard rotation and output reverse rotation but only on the 1.91 and 2.11 ratios. My ratio is 1.52. However, I would still have to go purchase two new trans to get these ratios since you can,t CHEAPLY change the ratio.

JK does present some middle ground though.

I might be better off buying two standard rot 502's. (this saves money on the long block , the dist, and create a more modern setup for the MPI and overall setup.). Buy two 1.91 trans and convert one to opposite. (this spends money). and still keep my engine beds, 454 engine mounts, shafts, and alignment since I'm using the same size 71/72 BW trans(this saves a lot of money for boatyard expense)

Mbam

The rotation is NOT selectable, it is built into the reduction section. All ratios except the 1.88/1.91 turn the same as the input direction. The 1.88/1.91 turns opposite.

VeeCat

Are telling me all the twin inboard boats built in America for the last 25 years all have a right an left hand rotation gas engine?
Where are all these left hand rotation engines and mercuiser repair manuals?
Transmission Raises.................ALL-IN

VeeCat

What year and Make of motor are presently in the boat Mercruiser Bluewater Inboard, Crusader, Chrysler, even Chris*Craft motors, ect?

What Make is the Boat?

Is it straight Inboard or Vee-drive?

Make a call to BorgWarner with the ratio/reduction and serial number or possibly Mercruiser if that is motor make.

Transmission Calls and ALL-IN..................

Mbam

That is pretty much the case prior to the late 80's/ early 90's. Not sure when Velvet Drive came out with the 5000 series (which is reversible), but looking at my Merc stuff 1994 is the first listing for the Hurth (which is also reversible) on a small block, and 1989 for a big block.

jerosejr

Veecat... you lose
Yes Up until about 10 years ago, counter rotation in an inboard or vdrive situation was achieved with c/r engines.
I don't know about sterndrive but I suspect that sterndrive and outboard achieved c/r in the gear packs long before inboards.

My boat is a 1973 Cary, 33 feet, twin 454 cr. velvet drive 1.51.
(when u go to thunderboatalley.com, my hull is the opening pic with Big Donzi at the wheel...in other words, the FIRST cigarette boat !!! thank you)

New Info from Velvet drive:

The 1.91 amd 2.11 trans were built from the factory to accept either rotation and output the opposite rotation. As mentioned above, you could select to accept left or right and output the opposite by indexing the pump.
However, this presents another proplem.... what do u do about your standard rotation engine.

I think NOBODY wins

Mbam

jerosejr,

you CANNOT select the output rotation on this style transmission - period.

The pump will only pump oil in 1 direction, the pump indexing allows you to select which crankshaft direction it will be. This in no way changes the out put direction. It simply will not work if it does not match the engine rotation.

To me this is not about winning or losing, just bothers me to see inaccurate information.

jerosejr

Mbam
Concerning the 1.88 and 1.91 trans ONLY:

You are saying that you had to order from the factory whichever rotation you needed and what came from the factory was not reversible with a pump indexing.

If that true I'll buy it, but it still doesn't change the fact that if you had two of these 1.91 trans you would face a problem now with your other engine turning the prop the wrong (inboard) way.

BW explains that if you want two standard engines you would have to do this:

Starboard: use a standard rot engine, buy a 1.91 that accepts standard and converts to opposite. This swings the prop out.

Port: use a standard rot engine, buy a 2.11 or 1.51 that accepts standard and outputs standard. Then have your props tuned slightly different. (what a crock)

This is straight from BW.

Mbam

Yep, you got it. Not sure what you mean order the rotation you need, all the 1.88 / 1.91 reverse engine rotation at the output.

I agree, it does not sit right with me to have different ratios, but it will work OK once you adjust the prop.

VeeCat

Back again,
It sounds like from your call to Velvet drive that on a 1.88/1.91you hypothetically order a right hand and left hand out put transmission and index each for standard rotation. This on what they currently build.
Your Magnum is over thirty years old
not twenty
I did some transmission work (parts changing) including indexing on some Mercruiser Blue water Inboard/Vee drives in 1984. The trannys were marked Borg/warner Velvet drive and painted black by Mercruiser. I attended Mercruiser School and at that time you could index and change the rotation. At that time all Mercruiser motors including I/O and Inboard were standard rotation. Only one direction the engines turned period. Who Builds a left hand engine today?
Now.......
In the Oldin Days it was quite common to see left and right hand engines Old Chris's, Old Hercules, ect. I believe that the last one I remember that was a left hand was on a 42' 1972 Chris Craft Commander with 427's. The engines had freeze damage and we bought the last set (left and right) on Chris motor plant shelves in about 1990 or so.
Your tranny's may not be switchable as the Mercruiser version was in the early 80's. I only know back to the era.
I do know that most marine gas engines produced today are not running backwards. If any are.
I still believe that transmissions are your best choice if you are repowering your Magnum. I have sold millions of dollars worth of boats thru the years and will tell you a backward running motor will not be a plus at the resale table. Standard Merc EFI 502's are a big plus in your corner.
Bam,
Not doubting your knowledge at all. I have looked at a lot of Crusaders that the tranny serial number plate starts with LH or RH-???, indicating that there is a left hand and right hand tranny.
Magnum Man (neat boats)
At the very least
I can get you whatever new tranny Merc currently sells at cost plus freight from Dallas to you.
VeeCat