Twin Screw Engine Rotation...

Engines, Shafts, Steering, Struts, Rudders, etc.
RBrown
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Re: Twin Screw Engine Rotation...

Postby RBrown » Tue Jan 31, 2017 6:47 pm

I replaced both distributors on our 454 Crusaders with Delco EST kits two years ago. I have one reverse rotation engine and I thought that I needed two different distributors. I looked at the original distributors and they had two different model numbers. The difference in the model number indicated that one was that one was for a reverse rotation engine. After several years of on and off research I found out that both engines use the same distributors. The difference is that one engine has a timing chain and the other has a timing gear set. If you go the the Marine Parts Source website you can find your engine and look up the exploded parts diagrams for your engine. My diagrams had part numbers for LH & RH engines. The distributors had the same part number.

I am very happy with the EST distributors. The engines start better and idle much smoother. I must have had the old points distributors set and operating optimally since there is no measurable gain in performance of fuel economy.

Rob
Last edited by RBrown on Tue Jan 31, 2017 11:36 pm, edited 1 time in total.
1986 39' Marinette Double Cabin
Misty Blue
350 HP. Crusaders
Home Port: New Buffalo, MI.

EWRice
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Re: Twin Screw Engine Rotation...

Postby EWRice » Tue Jan 31, 2017 7:35 pm

The cams do spin clockwise in both engines by means of chain in one and gear to gear on the other as stated, however, I believe the cams are different between the two. I will have to double check my sources on this.
Muskegon Lake
1972 32' Express flybridge
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

Leviathon
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Re: Twin Screw Engine Rotation...

Postby Leviathon » Tue Jan 31, 2017 9:42 pm

I think the cams are different. The gear on the reverse rotation engine camshaft is ground so that the distributor still turns the same way. Also on the tranny, model is important. I am working on 2 crusaders to replace my tired 360 Chryslers, and the trannys turn opposite the input shaft. So, starboard engine is standard rotation, tranny is reverse rotation. Port engine is reverse rotation and tranny turns prop standard rotation. I am interested to see how everything is going to line up going from Chrysler to Crusader in the engine compartment.
Steve and Mary Levi
1973 32' Marinette Fisherman
Twin Chrysler 360's
El Ohssa
St. Joseph, Michigan

EWRice
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Re: Twin Screw Engine Rotation...

Postby EWRice » Tue Jan 31, 2017 10:04 pm

Just checked the book. RH is different than LH cams. Distributor gear is b the same on both.
Muskegon Lake
1972 32' Express flybridge
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

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carl
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Re: Twin Screw Engine Rotation...

Postby carl » Tue Jan 31, 2017 10:52 pm

Lots of great information coming in here which helps point me in the right direction as I get familiar with my twin screw Crusaders. Thank You.
1990 Marinette 32' Sedan Fly Bridge "IKOI"
Twin Crusader 350's (Closed Loop Cooling)
Bow to Stern Full On Restoration in Progress
Chickamauga Lake, Tennessee
A boat is always safe at shore, but that's not what its built for...

TinLizzy
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Re: Twin Screw Engine Rotation...

Postby TinLizzy » Tue Jan 31, 2017 11:01 pm

It is also possible that someone could have two of the same direction engines and full reversing transmissions, i.e. zf hurth transmissions. Meaning that the transmissions can take full power all day long in either direction. I do not know if there is a velvet drive that does that.
Rodney
1975 28 Express-Twin 318 Raw Water cooled
Portage Canal Waterway-Lake Superior

RBrown
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Re: Twin Screw Engine Rotation...

Postby RBrown » Tue Jan 31, 2017 11:40 pm

Oops. Thanks for setting me straight on the cams. I don't know what I was thinking. I went back and removed my comments about the cams.

Rob
1986 39' Marinette Double Cabin
Misty Blue
350 HP. Crusaders
Home Port: New Buffalo, MI.

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carl
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Re: Twin Screw Engine Rotation...

Postby carl » Wed Feb 01, 2017 5:29 am

www.marinepartssource.com This is an excellent link you shared with me, looks like the source for everything I will need, cleared up a lot of questions for me. Thank You
1990 Marinette 32' Sedan Fly Bridge "IKOI"
Twin Crusader 350's (Closed Loop Cooling)
Bow to Stern Full On Restoration in Progress
Chickamauga Lake, Tennessee
A boat is always safe at shore, but that's not what its built for...

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john26
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Re: Twin Screw Engine Rotation...

Postby john26 » Wed Feb 01, 2017 10:52 am

Hi to everyone.Maybe a little off subject but, what rotation is normal for a single screw looking from flywheel end?I should know this..My motor is listed on ID plate as a 255R so does the R possibly indicate reverse rotation or maybe reman.Ford 255 Mercruisers were only made for a couple of years 73-74 ish..very little info available.
Thanks for any help..
John
1966 Marinette 26 Flybridge single 351w
1990 Sea Ray 160
1992 Reef Runner
1984 Oday 23

Fastjeff
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Re: Twin Screw Engine Rotation...

Postby Fastjeff » Wed Feb 01, 2017 11:10 am

Usually reverse rotating.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington