Twin Screw Engine Rotation...

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

Post by RBrown »

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...

Post by EWRice »

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
"AL13"
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...

Post by Leviathon »

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
SBC Crusaders
El Ohssa
St. Joseph, Michigan
EWRice
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Re: Twin Screw Engine Rotation...

Post by EWRice »

Just checked the book. RH is different than LH cams. Distributor gear is b the same on both.
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson
carl
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Re: Twin Screw Engine Rotation...

Post by carl »

BigM
Last edited by carl on Wed Jul 10, 2019 10:53 am, edited 1 time in total.
TinLizzy
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Location: Lake Superior-Michigan's U.P.

Re: Twin Screw Engine Rotation...

Post by TinLizzy »

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 350 Chevy's, SOLD
1990 32 Express--Twin Mercruiser 454 with Bravo I outdrives
Portage Canal Waterway-Upper Peninsula,Lake Superior
RBrown
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Re: Twin Screw Engine Rotation...

Post by RBrown »

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.
carl
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Joined: Sun Feb 08, 2015 5:58 pm

Re: Twin Screw Engine Rotation...

Post by carl »

BigM
Last edited by carl on Wed Jul 10, 2019 10:52 am, edited 1 time in total.
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john26
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Re: Twin Screw Engine Rotation...

Post by john26 »

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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Location: Rock Halll, MD

Re: Twin Screw Engine Rotation...

Post by Fastjeff »

Usually reverse rotating.

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