Merc 454 Reverse and Standard Rotation Question.
 

Ok Guru's, you educated me so well on part numbers, thanks by the way, that I thought I would up the ante.
On My twin 454 mercruiser 370's with borg warner transmissions and TRS drives, where does the reverse rotation occur? Is it in the drives, transmissions or engines? Is there anything special I should do when rebuilding the engines to compensate for the rotation?

Re: Merc 454 Reverse and Standard Rotation Question.
 

In the drive.

Re: Merc 454 Reverse and Standard Rotation Question.
 

Well, USUALLY in the drive, but not always. If you have one standard and one reverse rotation engine it will be obvious by looking under the hatch as they crank over. With opposite rotation TRS gearcases, one will have a small "RH" stamped in the end of the propshaft; the other will be marked "LH". If you have an oppostte rotation engine, then there are some considerable differences, including the cam and starter in the parts catagory. --- Jer

Re: Merc 454 Reverse and Standard Rotation Question.
 

Ok, I checked the prop shafts, and sure enough, there is a LH and RH stamp on each. Does this mean I do not have to worry with the engines and just set them up as standard rotating engines?

Re: Merc 454 Reverse and Standard Rotation Question.
 

Borg Warner trans can not take full power in reverse. The trans has to be set up internally to run backwards on a counter rotating engine. The trans will be connected to the shift cable exactly as a standard rotation setup.

Re: Merc 454 Reverse and Standard Rotation Question.
 

You got 2 LH motors,standard rotation. Both motors will take same parts.

Re: Merc 454 Reverse and Standard Rotation Question.
 

Yep, what he said. And no need to worry about the trannys cause they will both be std. rotation. If you really had opposite rotation engines, the gearoter housing on the B/W would have been indexed for that and you would NOT have been putting full forward power through the planetary gears. Just remember; when the time comes to rebuild the lower gearcases, they take lots or different parts. --- Jer

Re: Merc 454 Reverse and Standard Rotation Question.
 

Thanks for all the valuable info, Maintaining the boat is much easier with you guys backing me up. :cool:

Re: Merc 454 Reverse and Standard Rotation Question.
 

I'm quite sure you don't have a reverse rotation engine. I read in another post of yours about one of your motors was a Gen V and the other a Mark IV. The raw water pump on a Gen V is indexed differently and the in/out are not in the same location as the Mk IV. (I've dealt with this before)

Good luck,

Kurt

Re: Merc 454 Reverse and Standard Rotation Question.
 

yes, to reinterate the opposing direction happens in the lower gears of the drive not the upper gears.

Re: Merc 454 Reverse and Standard Rotation Question.
 

If you are rebuilding a counter rotation engine, the pistons and rods go in backwards compared to the regular motor. I found this out by bringing the rod and piston assy back to the shop, thinking they put them on wrong. Learn something new everyday... BBB :eek:

Re: Merc 454 Reverse and Standard Rotation Question.
 

Oh , BTW all the hi perf. motors are all standard rotation. I don't think they would have made a 370 opposite. but it could be done.

Re: Merc 454 Reverse and Standard Rotation Question.
 

HUH?? I guess I am a bit "backward" but I just can't picture how you can install a piston backwards without having all those funny shapes on the piston dome interfering with valves and head chambers when you crank it over unless you have strictly flattops. Could you explain further? --- Jer

Re: Merc 454 Reverse and Standard Rotation Question.
 

actually the rod is backwards, the piston is installed backwards on the rod. The bearing tangs end up the other way. The valve notches would have to be in the usual place. I should have made this more clear ! Basically the numbered side goes in instead of out. BBB

Re: Merc 454 Reverse and Standard Rotation Question.
 

Not following the rod thing. So rods actually have an in and an out side to them? If so, what is the difference?

Re: Merc 454 Reverse and Standard Rotation Question.
 

One side of the rod is chamfered to clear the crank radius, the rods ALWAYS go on the crank with the chamfer facing the outer ends of the journal. So happens this is with the bearing tangs away from the cam.

If the pistons have the pin offset from the centerline there will be an arrow, notch or some other form of ID to represent the normal front of the engine. I don't remember ever seeing a domed piston with an offset pin. Normally you will see it on a dished OR flat top piston with 4 valve notches so it can be used on both sides of the engine. If it was a domed piston (or single valve relief) you would need 4 rights and 4 lefts.

On a counter rotate you would install the pistons so the notch faced the rear. Assuming a notch piston you would just take the pistons/rods from the right bank and put them on the left & vice versa. If it mattered to you to keep the rod numbering correct, or if they were domed you would have to swap them on the rods.

I had to really strain my memory to remember all this, has been a while since I put an engine together :)

Re: Merc 454 Reverse and Standard Rotation Question.
 

I can't open the motor up beacuse it's in the boat. I know there definately was a difference in assembly.
Thanks, Marc. You always share great advice on here. And steer people in the right direction. BBB

Re: Merc 454 Reverse and Standard Rotation Question.
 

If I may chime in.

Marc pretty good memory.

I dont need to remember because Im staring at one.
Then again my brains toast anyway.

Rods make no difference in the way they go in a counter
or a standard.

Its all about the chamfer facing the radius on the
crank.

Big block billys pistons had to have been offset on the pins.

From my understanding there were two ways of counter
rotation. Custom Ground cam or a gear drive two spin the Camshaft the original way.

The distributer gear is ground different to keep the distributer and oil pump spinning the same way.
The firing order on this custom grind is opposite of STD chevy. 12756348

All reverse rotation engines have that firing order, and in saying that with a belt drive, timing chain, or three-gear(idler) the cam has to be ground specifically for that application so that the cam and crank both turn clockwise (as viewed from behind the engine). In this case the cam gear and distributor gear are ground to turn the distributor and oil pump in the standard direction.
the two-gear timing setup used in stock Merc counter-rotating engines spins the cam in the standard rotation while the crank spins in the opposite direction, allowing a standard distributor gear to be used.

possible differences
1) custom ground cam shaft
2) Distributer gear
3) three gear Idler (no Timing chain)
4) Rear main Seal
5)pistons if offset pins.. look for notches or arrows

Something to think about
Where the oil hole is placed on the journal
of the crank should be in close proximity of where the piston
actualy fires. This would in theory insure a film of oil in between. In a counter rotation the Oil hole is not at its proper clock position.

Cross drilling the crank or atleast adding a radius (chamfer) to the other side of the oil journal which feeds the rod bearing.

Heres a question Marc.
Are the merc. part #,s different from a merc counter crank
compared to a standard rotation crank?

Gerry

Re: Merc 454 Reverse and Standard Rotation Question.
 

Look at the big brain on Gerry!!! :D :drink:

Merry Christmas Gerry...Did you figure out what to do with your setup?

Re: Merc 454 Reverse and Standard Rotation Question.
 

You guys got pretty bogged down in specifics, but the fact that this set-up is an outdrive engine then it is a standard rotation. Only inboards and v-drives used opposite rotation engines. It's much cheaper and easier to do the reversing in the outdrive.
The newer inboards and v-drives use standard rotation engines with a reversing transmission on one side. Other than Marine Power in Louisiana, I don't know of anybody building a new opposite rotation engine these days.

Re: Merc 454 Reverse and Standard Rotation Question.
 

As already stated: "usually, but not always" I serviced a 24' Cig. for years that came direct from the factory with a reverse rotation Mercrusier Cyclone, B/W trans. and RH rotation TRS drive using a LH wheel. Now THAT was one weird set-up! The steering was on the port side also to compensate for torque. So remember; Just when you think you have everything figured out, somebody does something like that to you. Merry Christmas! --- Jer

Re: Merc 454 Reverse and Standard Rotation Question.
 

WHAZ UP?
Merry Christmas right back at ya Craig!!

I have contracted a deal with Tommy at chief.
for some big Dart 18 degree chiefs.
with complete top end.

When I blow these up I will go to turbines :D

Hope all is well

Gerry

Re: Merc 454 Reverse and Standard Rotation Question.
 

Also, the cam gear is pressed on a reverse rotation. The cam and the gearset is the only change from right to left.
Then your fireing order will be different on the left hand. On the Thunderbolt dist. cap is set up for both firing orders if you have the older style mercurisers.

Re: Merc 454 Reverse and Standard Rotation Question.
 

But don't forget that the starter and starter drive clutch/gear are different also with reverse rotating engines. --- Jer

Re: Merc 454 Reverse and Standard Rotation Question.
 

...and people wonder why marine mechanics go psycho sometimes!