Replaced Counter Rotating Engine with Standard... Suggestions?

[Texun]

Here's the saga from the beginning....

We recently purchased the '81 360 Express knowing and deal compensating for the cost to be incurred to replace the port engine. Plans were to wait until post season and rebuild / replace the engine.

Well, I ran across a really good deal on a donor boat with an almost new 454 I/O setup. The mechanic I have used for years made a mistake when checking rotation of the engine. Seems that it's pretty standard for newer models to handle the rotation in the gear box vs. the older technology of counter rotation engines. I have no clue as this is my first rodeo with twin screws. Needless to say, learning a lot REALLY fast.

Since the bell housings and starters were different due to the I/O vs. direct drive inboards, these parts along with the transmission were used from my original setup.

After roughly $6,000 for engine and labor to make the exchange, the marina swapping the engines can't seem to get the engine started. Appears the starter from my old engine is spinning the engine the wrong direction, and therefore reversing the intake and exhaust functions.

The suggestion was made to install the opposite rotation starter and rh prop to counter the rotation. I am not particularly fond of this suggestion as I am assuming there would be a torque and therefore list issue as throttle is increased with both standard rotating props.

Another suggestion was to switch out the gearbox for counter rotation. This seemed feasible and most likely the least costly way to get the proper rotation.

Other than that, the mechanic that originally checked the engine and errored on rotation will rebuild the original motor over the next couple of months and we will swap out for the motor that now sits in the boat.

Suggestions / recommendations?

 

[Crazyhorse]

Swap the cam for a boat cam...

 

[Jimmy Buoy]

Both my engines are standard rotation. From what I understand, to have the props counter rotate one transmission is in "reverse" while the other is in "forward" to have both props thrusting in the same direction at the same time.

Can you not setup your transmission cable to select "reverse" even though your helm control would be indicating "forward"? I don't think the tranny's would care which direction they are spinning and the gear ratios should be very close in either forward or reverse. What gear ratios are listed on your transmissions for forward/reverse?

Keep in mind that I have no training/experience with this issue - just thinkin out loud.:huh:

 

[Redhook98]

In order to "reverse" one drive, you will have to install the oil pump on the opposite side of the transmission. If you decide to simply put it in reverse, you will blow a pump very very quickly. You should never exceed appx 1500-1800 RPMs in reverse. In an I/O configuration, you could do that, but not in a hydraulic transmission. Go for the tranny rebuild with the oil pump in the correct position (and thus reversing the direction of the tranny correctly) and get the correct starter.

 

[Redhook98]

Swap the cam for a boat cam...

Or do that....... Thats the only real difference between counter-rotating motors. (and firing order).

 

[Happy Hour IV]

1988 454's. I am not so sure the cams are different. One engine has gears for camshaft drive and the other has a chain so the camshafts turn differently relative to the crankshaft. If you do anything to get the crank to change direction you may have to look at belt driven accessories. The alternator may have uni-directional cooling fins. Water pump impeller may be an issue. Freshwater pump may also be a problem.

 

[SCORPIO]

My '89 300 DA has two standard rotation engines AND two standard rotation outdrives, so both props are turning the same direction. I have no problems with this setup, although I have never owned a boat with counter rotating props, so I have nothing for comparison. I'd try it before dumping a ton of money into a reverse rotation OD. Wait until you need drive work then address the problem.
JMHO

 

[Redhook98]

My '89 300 DA has two standard rotation engines AND two standard rotation outdrives, so both props are turning the same direction. I have no problems with this setup, although I have never owned a boat with counter rotating props, so I have nothing for comparison. I'd try it before dumping a ton of money into a reverse rotation OD. Wait until you need drive work then address the problem.
JMHO

Your Alpha 1's are a little different. He can not just run his transmission in reverse like you can. It will blow the oil pump. He either has to make the engine into a reverse rotation, or rework the transmission so that it goes the other way in forward.

I have friends here with your exact boat. They also have Alpha 1's that turn the same way. He has no problems with it either. Your also turning much smaller props and you can compensate for the walk by turning the drives. Not so with inboards.

 

[tmikesh81]

1988 454's. I am not so sure the cams are different. One engine has gears for camshaft drive and the other has a chain so the camshafts turn differently relative to the crankshaft. If you do anything to get the crank to change direction you may have to look at belt driven accessories. The alternator may have uni-directional cooling fins. Water pump impeller may be an issue. Freshwater pump may also be a problem.

The cams are different.. they are reverse ground for the backwards firing order.. the gears are on the backwards engine.. to change direction of the cam so it will rotate the same as the standard engine.. and so the distribitor spins the same way as the standard.. and oil pump...

 

[SCORPIO]

My Aplhas don't run in reverse, both props spin in the same direction. What I was getting at is that not all twin engine boats have counter-rotating props. He may want to try the boat with both props spinning the same way and see how he likes it.

 

[Redhook98]

My Aplhas don't run in reverse, both props spin in the same direction. What I was getting at is that not all twin engine boats have counter-rotating props. He may want to try the boat with both props spinning the same way and see how he likes it.

What I said was that you CAN run yours in reverse to get counter-rotating drives if you wanted. It is simply a matter of switching props and repositioning your shift cable.

What I was saying about HIS boat is that he can not even try to run in his current config because his engine and drive do not match up. The tranny can not support the direction of his motor without being modified. He has to change the engine rotation, or the tranny rotation.

Sure, go ahead and try to run 2 inboards in the same rotation. You will walk sideways, hard, as soon as you put it in gear. Like I was saying, 2 inboards turning the same direction do not react the same as 2 I/O's. They are different animals.

 

[Texun]

Thanks everyone!!!!

Went back to my mechanic. He has agreed to stand behind his call on the engine. He has offered rebuild the original engine, and we'll share the workload of swapping them out.

I expected there was no "easy" solution, or one that seemed relatively inexpensive but one can always hope...

Main thing to me is to get it back to a state of functioning correctly and all options seemed were adding more wrongs to the existing mess... So I am taking him up and we'll be working on it over the next month... Wish us luck!!!

Thanks again,
Tex

 

[Hampton]

We're starting to see more and more people standing behind their work. I think it' a sign of the times. During the fake boom years, people would say "Screw you, I've got plenty of customers." Now that we're back to reality, people's reputation will begin to matter again. I hope those that stayed true succeed and the others fail.

 

[Redhook98]

We're starting to see more and more people standing behind their work. I think it' a sign of the times. During the fake boom years, people would say "Screw you, I've got plenty of customers." Now that we're back to reality, people's reputation will begin to matter again. I hope those that stayed true succeed and the others fail.

I agree 100% :smt038

 

[SCORPIO]

I'm think I'm confused, I thought the boat in question was running outdrives. If this is an inboard with a transmission, then Redhook98 is correct, my bad.

 

[stuckinforward]

for future reference and the memory bank, backward engines do run a gear on the camshaft thus spinning the opposite of crank rotation and a different firing order, unlike the chain which spins with crank rotation, and the most important part of all are, the PISTONS MUST be flipped because of an offset, if not you will get a knock from the engine. pull out a good Merc manual when attempting to use a backwards as a normal....sorry for butting in but, dont make the same mistake i made, its always free the second time!

 

[sprink56]

If you have Velvet Drives or Borg Warners...forget the reverse idea...the reverse gears are not designed for the strain. An easy fix would be to install a Hurth/ZF tranny set up. I think they are completely reversible in that you simply turn them around and swap the linkage arm to the opposite side....so I've been told. Worth looking into.:thumbsup:

 

[stuckinforward]

good point, the inline Borgs 10-17's and 10-18's use a planetary for reverse and if you attempt to use reverse as forward you will burn the planets, these planet gears turn approximately 4 times engine speed, so if you are doing 4000 rpm that means the planets are spinning 12000 and will blow or burn up within minutes. nowadays, utilized are full power transmissions, 5000 series, ZF hurth, Twin Disc and it also eliminates counter rotating engines. these transmissions use close to identical clutch packs and can be used as forward in both selector ranges and it is just a matter of swapping the cables around, every manufacturer got away from counter engines, and ford is completely out of the marine market

 

[Jimmy Buoy]

Both my engines are standard rotation. From what I understand, to have the props counter rotate one transmission is in "reverse" while the other is in "forward" to have both props thrusting in the same direction at the same time.

Can you not setup your transmission cable to select "reverse" even though your helm control would be indicating "forward"? I don't think the tranny's would care which direction they are spinning and the gear ratios should be very close in either forward or reverse. What gear ratios are listed on your transmissions for forward/reverse?

Keep in mind that I have no training/experience with this issue - just thinkin out loud.:huh:

Guess I should have added that I have ZF Trannies...

 

[ShamuToo]

Or do that....... Thats the only real difference between counter-rotating motors. (and firing order).

Sorry but you're way wrong. The motor turns the opposite way because of the opposite rotation cam, but you have to replace the timing chain and gears in a standard rotation for a gear to gear set up for the opposite rotation. The crank with turn opposite but the cam still turns in the standard rotation. The cam timing is what makes the valves open in the correct order for the crank to turn opposite. Then the pistons have to have the indicator notches facing the back of the engine instead of the front for the opposite rotation. This is due to the fact that the wrist pin holes are offset in the direction of the rotation to counter balance the thrust of the piston against the cylinder wall created by the spinning mass of the cranl, rods and piston. Reverse the rotation, and you have to reverse the intalled orientation of the pistons. This cannot be done with a piston that has been running in the hole already, but requires boring and replacing the pistons. Belt driven raw water pumps are an issue also.

Go you can get a reverse rotaion gearbox if the gear ratio can be matched. If they are BW 71 or 72C's. Then see if you can replace with the CR suffix. (the R stands for reverse.)