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Engine rotation ID

T

thelasthour

Member
This is always confusing for m

This is always confusing for me and some mechanics so here goes. My props spin away from each other in forward gear like they should. My transmissions are the rare breed that reverse the normal engine rotation (velvet 71c i think) So what rotation is my starboard engine? My starboard engine model # is 50572-06 ser # 661545. My port engine model # is 50573-06 ser # 660263. My second question is what are the correct oil filters for these models (sierra please). Am i correct that I would purchase a starter that is "opposite rotation" of my engine?

Steve
 
"Steve,

I have a spare RH S

"Steve,

I have a spare RH Starter as a result of this same situation and eventually I was told....LOOK at the rotation from the flywheel....Clockwise or Counterclockwise ....DONE !"
 
"So if my prop is going clockw

"So if my prop is going clockwise, and my trans is reversing it then my engine is counterclockwise, and counter rotation and my port motor is standard rotation. Is that right?
Steve"
 
"hmmmm, verify you have a 1.91

"hmmmm, verify you have a 1.91:1 reduction ratio. That is the only 71c that reverses (in forward).
If that is the case, AND the starboard prop is CW as viewed from the back, then the Starboard engine is "standard rotation" ie; LH, and has a timing chain, not a gear."
 
"Dave,
I thought the gea

"Dave,
I thought the gear reduction was 1.88-1 which i think is the predecessor to 1.91-1 (my memory is failing me) but I'm POSITIVE that the transmissions reverse the engine rotation, because when we did the repower, the shop put them in backwards the first time since they did not expect the gear to do that."
 
"Steve; Yes, both the 1.88 an

"Steve; Yes, both the 1.88 and the 1.91 reverse. I think the 1.88 is a later design, my notes show only the the 1.91 as having the old style bearing retainer, the 1.88 from the start had the newer design housing."
 
"Steve:

DD is spot on.

T

"Steve:

DD is spot on.

The 50572 is the LH 350 and the '573 is the RH, per the crusader owner's manual's "decoder ring". Both were build with in-line gears.

You should be able to find your filter here:
http://www.marineengine.com/parts/sierra_marine/catalog.html?[url]http://www.marineen gine.com/parts/sierra_marine/crusader.html[/url]

If the link doesn't work, go to the top of this page and click on "boat engine parts". then Crusader and then oil filters. My older Big blocks use the "long ford" style, on the remote adapter."
 
"Steve:

Since one of your t

"Steve:

Since one of your trannies reverses the rotation internally, then both of your engines are 'normal' rotation. This is true for all outdrive boats and every Vee-drive I've seen to date (though there may be an oddball out there).

Consider yourself lucky, for reverse rotators are getting hard to find.

Jeff"
 
"Jeff, by design both his tran

"Jeff, by design both his trannies reverse engine rotation so starboard motor is normal left hand rotation and port motor is odd ball right hand rotation, as DD and MM posted."
 
""So if my prop is going c

""So if my prop is going clockwise, and my trans is reversing it then my engine is counterclockwise, and counter rotation and my port motor is standard rotation. Is that right?"

Counter clockwise rotation is standard rotation, clockwise is reverse rotation."
 
"Steve, its not a matter of be

"Steve, its not a matter of being logical, its just the way a few of the old BW transmissions were designed. The input to your transmission is a rotating shaft spinning one way, and the output of the transmission is a rotating shaft spinning in the opposite direction of the input shaft--that's just life with the old BW 1.91:1 and 1.88:1 drives.

If you are still confused consider that three experts plus myself have declared the following for your boat:

Starboard Motor: standard left hand (CCW) rotation
Port Motor: reverse right hand (CW) rotation

The reason your mechanic got confused and installed the props on the wrong side is because most in line transmissions don't reverse the engine rotation, so to get clockwise prop rotation the starboard motor would normally be reverse right hand (CW) rotation and vice versa."
 
Oh brother! There's alway

Oh brother! There's always one out there!

Is this a Vee drive? Can't fathom any reason to install trannies that BOTH reverse the rotation.

Jeff
 
"It is the nature of the beast

"It is the nature of the beast and there is more than one out there.

These aren't "full power reversing gears"; they just happen to have input and output shafts rotations that are opposite, due to the internals. So, if you want counter-rotating props (good choice) and you need that gear ratio, you just swap engines from their 'traditional' locations.

Not everybody is 'happy' with the newer designs and prefer the 'proven' technology....BW inline gears have been around a long time and have a great track records. Not everybody can afford them either."
 
"If you think this is confusin

"If you think this is confusing, try figuring out which type an old Chris Craft SB Chevy is with the drive coming off the front (damper pulley) end of the motor!

Jeff"
 
""BW inline gears have bee

""BW inline gears have been around a long time and have a great track records. "

Yep; mine are 35 years old, work and look fine. I am continually impressed at the durability of the internals. They use heavy castings, gears, etc. The bronze/steel clutches appear to not shed material, and get wasted only when slipped during low oil pressure events. And even then, they warp and not otherwise send bits into the fluid. I recently read on a offshore race forum how they are still used to deliver over 1000HP to outdrives, with minor tweeks. I will say that any water that is ingested is tough to remove. Fluid movement thru the large pistion/cylinder assembly is slight; even 4 to 5 changes will not get all the water out."
 
"Mechanically the old BW drive

"Mechanically the old BW drives have proven themselves very robust. Many, many boats were made with the 1.91:1 and 1.88:1 gears in the 1980's from Chris Crafts to Egg Harbors to Trojans and most are running well 25 years later, a testimony to their durability. There are a dozen boats at my marina with these old gears whirring away with nary a problem other than the occasional fluid leak at the rear seal, etc. I am happy to hear DD report that that the castings are heavily made because I'm more concerned with the castings rusting away than with a failure of an internal component.

Just have to make sure the oil cooler is in good shape and the fluid gets changed..."
 
"..."Just have to make sur

"..."Just have to make sure the oil cooler is in good shape and the fluid gets changed..."

Right! And be DAMN sure there's enough oil in them. The entire trans takes a shockingly small amount of oil (mine take just over 2 quarts). If they are a cup low, they can slip! And when they slip, they burn up.

The safest (and factory recommended) way to check the oil level is this: When fully warmed up, have someone pull the dipstick immediately after shutting the engine down. Is MUST be at the FULL mark. If not add fluid. Then, after waiting overnight, note where the level is on the stick (cold). Use that level--regardless of what it is--to determine the fluid level.


Jeff

Note: An average car or truck trans uses 7 to 15 quarts of oil."
 
Re: "Steve,

I have a spare RH S

On forward flywheel engines you have to look from the front of the engine which is aft and look towards the flywheel. Standard rotation is CCW and opposite rotation is CW, meaning that you need a CW starter for port engine and a CCW starter for starboard. I would love to hear a rebuttal.

Thetumbleweed
 
Re: "If you think this is confusin

Man jeff you shur got that right got mine prity well figured out now and I think the guy that built it is still lafing. At us.
 
Re: "Steve,

I have a spare RH S

You are right that's the way my sm chev q's are also fyi the dist gears are cu the same and turn the same way. But the firering order if different to make it worce if you look at a cc book and it shows a lefthand fireing order that not the engines rotashion its the left side engine in the boat ae port engine. Oh and for more cc fun try and figure out the cooling systems don't know how many thay messed up opps made but good luck finding old parts in the scrap row now I know why thay don't make them enymore.
 
Re: "If you think this is confusin

fastjeff said:
"If you think this is confusing, try figuring out which type an old Chris Craft SB Chevy is with the drive coming off the front (damper pulley) end of the motor!

Jeff"
Click to expand...

You got that right iv got a couple that's why thay call them chris crap. My local marines won't even talk abot them at the bar.
 
Re: "If you think this is confusin

FYI, this thread is over one year old.... last post to the original question, by Jeff, 02-11-2010 .

But this cracks me up!
In January of this year, Thetumbleweed posts:
Thetumbleweed said:
On forward flywheel engines you have to look from the front of the engine which is aft and look towards the flywheel. Standard rotation is CCW and opposite rotation is CW............. I would love to hear a rebuttal.
Thetumbleweed
Click to expand...
This began with him on 01-20-2011, and in his own ChrisCraft thread (re; ChrisCraft's method for determining engine rotation). This was after ample examples, images and explanations. It was apparent that he only wanted hear what he had as a preconceived notion. He got upset, and cut and ran on 01-25-2011, leaving Chris, Glen, and myself with several not so pleasant comments.

I just now see that he was simultaneously posting incorrect info to this thread as well.
And as per his closing comment, it's almost as though he was looking to rattle a cage or two. :mad:

Oh well!

.
 
Last edited:
Re: "If you think this is confusin

Yea I know but I still check in on it is a good topic for the q engine installs by cc thay are a pain to figure out since v got a pair I'm working on now I think it was you that told me that the dist gears are ct different but mine are not how ever thay are I my 427! For Lh and Rh iv got the starboard running now but I can't find a starter for the port yet do you know if the motor part of the starter is interchangable with the different noses all I can find is the ones that bolt stright in mine bolt up from the bottom.??
 
Chris, apparently so! LOL We all tried to explain it to him!

Glen, I think that we touched on this, but if two distributors (one for RH and one for LH engines) are using the same gear and gear cut....., then it can only mean that the camshaft on the RH engine is being "two gear" driven..... which would turn the camshaft in the Std direction.
As for the starter motor.... eeek! Not sure what to suggest.
Are these Ford style Bendix drives..... or soleniod lever/arm style starter motors?
If solenoid arm........ and if you were to find the correct pinion and sprague clutch, could you not have a reverse motor built or rebuilt?
If Bendix drive, you now not only need a reverse armature, the Bendix must also work in reverse..... (I believe that they also use an internal sprague clutch).

Richard, at Seamanufacturing, is pretty darn sharp at Marine starters and alternators. It may be worth giving him a phone call.
 
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