I just got gave two free SBC motors. All I've got to do is take them out of a boat. A old ChrisCraft. The block #'s are 3970010.
I went to http://www.mortec.com But I'm not sure which one's I've got, I think they would be the industial 327's coming out of a boat, huh???? What do ya think?

 

That is a nice steel. I am not quite sure but I think marine motors spins opposite of street motors. Someone else will have to clarify me on that. Also they may come with aluminum heads which would kick but. Lots of marine stuff is aluminum for weight and corrosion properties. If it is a 327 it may not be a roller block, but that is okay. you could save it and always use it later for a project car.

 

i thought with dual marine motors, that one spins one way and the other spins, well, the other way.

 

where the hell did you hear that they spin backwards?!


lmao.


free motors (that arnt 305s) are cool.....

 

nope.


and if you were to make one spin the other way, wouldnt it make sence to use some form of tranny to do that? lmao.... i mean, who wants to redesign the motor to spin backwards just to spin the propeller the other way

 

As for the spinning backwards, if im not mistaken, you can make it spin the right way by just swapping out the marine cam for a standard cam.

 

i also remember my brother telling me that the marine motors are more likely to have cracked castings due to the fact that they see prolonged high rpm/load use. His solution to this was just to weld the crack and use it anyway.

 

Yea I am prety sure they spin the other way. No joke, wierd huh.

 

heh, wierd... every mercruiser ive ever worked on spun the right way......


and my dads twin diesel also spins the same way.....



now why in the world would you want one set to spin the other way? besides wasting money.






and if someone tells me it has to spin the other way to make the boat go straight...... you're a idiot.

think about it.

 

Volvo made a boat motor that was a Chevy engine, but spun backwards.

I guess they couldn't figure out all they had to do was change to a prop with a different pitch.

 

I am not really sure why but I know some of them do. I think since they are made specifically for marine use there must be some benifit.

 

If they spun opposite directions, then the motors would be fighting eachother..that makes absolutely no sense whatsoever

 

In a single motor marine application the motor can spin clockwise, or counter-clockwise. Depends on the mfg and whatever reasons they wanted too.

However, with dual motor setups one engine spins clockwise, and the other counter clockwise to eliminate the condition known as "prop-walk"

Prop Walk is when the rotation of a single propeller setup will cause the boat to "walk" sideways in its path. A clockwise turning propeller will cause the boat to sidestep in the direction of the prop rotation.

There are prop setups on production boats that use dual propellers on a single axis spining opposite of eachother. This completely cancels out propwalk at the expense of top speed, as well as decreasing time to get on plane.

I've been driving boats since I was 7 years old. My dads boat is so old it has a throttle control at the FEET!!

 

Score. Best answer yet. I am glad that you chimmed in. I knew there was a reason but I think people were starting to think I was crazy.

 

There in one other reason I can think of and thats torque steer. As has been noted before the counter rotating props cancel each other out. I remember when I drove my fathers stern drive tri hull it felt like it had power streering when turning right and power steering with the belt off the pump when turning to the left. This only occured when the boat went from idle to planning out.

Steve

Put a tbi on it and race someone in reverse.

 

With a Stearn drive/Outdrive setup prop rotation has a small effect on the steering bias. The new Counter Rotating assemblies stop this.

Boats are the last haven of the V8 though. No boat is complete without a 350 at the minimum. Imagine a world where the 350sbc is considered a "small" engine. Many boats come with 396's, 427's, and some even Dual 502's with roots type blowers on them!

My uncles friend named his boat "Wasted Wages". The boat is a 37ft long cigarette boat with twin blown 502's in it. His gas tank holds 300 gallons.:hail: :hail: :hail: Top speed somewhere near 120mph.

Now that the whole "reverse rotation" thing has been explained. Lets get back to the topic of what you will do with those 327's? ^_^

 

The motors spin the same as car motors, wether it be gas or deisel engines! I've worked as a engineer for the last 8 years, before that I was a deckhand. I've just finshed going through captains school, at the begining of next month I'll have my 100 ton Masters license. I've worked on river boats, crewboats and off shore tugs all my life. Also worked on motors such as Cats, Detroits, EMDs, Cummins and GM deisel engines all my life, back in '91 before I went offshore to work I worked at a Chevy dealership and I've never seen one turn backwards. On a twin screw boat the reduction gear will have the wheels turn opposite of each other, but not the engines there self. Did anyone go to http://www.mortec.com ? I'm just wondering what they are, I'll be getting them Saterday. Then tearing them down to mesaure the cranks to see what they are. It said they could be 302, 327 or 350, they could be a 2 or 4(I hope) bolt block. But one is going in the RS. I think I'll get a 302 crank for the rebuild since the #'s will match. They both(if both are good) will be machined for a roller cam though. I think a 302 with the Holley TBI will be a screamer! What do ya think! Thanks, Bobby

 

The motors spin the same as car motors, wether it be gas or deisel engines! I've worked as a engineer for the last 8 years, before that I was a deckhand. I've just finshed going through captains school, at the begining of next month I'll have my 100 ton Masters license. I've worked on river boats, crewboats and off shore tugs all my life. Also worked on motors such as Cats, Detroits, EMDs, Cummins and GM deisel engines all my life, back in '91 before I went offshore to work I worked at a Chevy dealership and I've never seen one turn backwards. On a twin screw boat the reduction gear will have the wheels turn opposite of each other, but not the engines there self. Did anyone go to http://www.mortec.com ? I'm just wondering what they are, I'll be getting them Saterday. Then tearing them down to mesaure the cranks to see what they are. It said they could be 302, 327 or 350, they could be a 2 or 4(I hope) bolt block. But one is going in the RS. I think I'll get a 302 crank for the rebuild since the #'s will match. They both(if both are good) will be machined for a roller cam though. I think a 302 with the Holley TBI will be a screamer! What do ya think! Thanks, Bobby

 

EXACTLY.


anyone that says the engine has to turn the other way to turn the prop the otherway will be amazed when i shift my car to "R" and it goes BACKWARDS!!






im a lil harsh somtimes, but comon people.. THINK!

 

No, its true. Some marine engines are built to turn the opposite way. The engine in my dads boat does, we tore that thing down and rebuilt it a few years ago, and we needed a few specific parts because of the direction it spun.

Some marine motors DO spin the opposite way. Its not a requirement, but they do. Don't ask me why, they just do.

 

Alright on some old(steam engines mainly and some of the first EMD's)engines they did have a direct drive. The motor had to come to a stop and then it did turn in reverse. But this is not a normal motor. These was used in some large boats, ships and trains back in the 30's- early 50's. Also on some deisel-electric engines(this is where a fuel engine turns a electric motor, used on large ships) they turn backwards, but the fuel burning motor turns in the normal direction. Thanks, Bobby

 

This is ridiculous. Youguys, (Chevypower, Mr.Dude_1 etc.) DON'T POST when you dont' know what your talking about!!

I have a 1992 Mastercraft Prostar190 with a Ford 351 Windsor inboard... DIRECT DRIVE! The engine runs reverse rotation. Same on ALL Ski Nautique's -even '03's. These are single engined, direct drive inboard ski and wakeboard boats. On these boats, the reason fro the reverse rotation is two fold. 1. you can use a "standard rotation" prop. 2. The prop torque on a reverse rotation engine counteracts the weight of the driver, leveling out the boat at speed (on RH drive boats, which most are). But as "FruityOne" said it depends on the manufacturer, year, etc as to engine rotation direction.

A reverse rotation engine has different
*camshaft
*starter
*distributer gear
*water pump

NOW, As for "stern drives"/ "inboard-outboards"/"mercruisers" -what ever you prefer to call them, those engines always turn clockwise, when viewed from the front. In twin engine applications, it is common and beneficial to have the props spinning in opposite directions! However, this is accomplished in the gear case, not the engine. So it's common in twin I/O applications to have twin, standard rotation engines, but counter rotating props. As FruityOne stated, counter rotating props DO improve handling, steering, and performance/top speed so no "KCobain147", they aren't "fighting each other". They are working together better than if the PROPS are spinning the same direction. And yes, Mr Dude, the boat does go straighter with counter rotating props(without countersteering) which is what allows it to go faster.

On an inboard, direct drive PLEASURE boat with twin engines, one spins forward, one spins backwards to get the props counter rotating. Chevy power, we're not talking about battle ships here. We're talking about small block powered pleasure boats. No "deck hands" needed in these little vessles LOL.

FYI, like FruityOne, I've owned and driven many boats for the past 20 years. Outboards, I/O's, Direct Drive Inboards. Forward rotating engines, and reverse rotating engines. I've seen and worked on all kinds, and I know why they use what they use to build them.

BTW, FruityOne, I used to have a boat w/a gas pedal. It was an '84 Hydrostream V-King. Ever heard of one? 18', 800 lb. hull, 220hp merc outboard, jack plate, dual steering, 26" Cleaver and a 26"chopper prop, trim on the wheel, gas pedal. The thing was a goer. It was BAD. It'd do over 85 mph on good water. I miss it.

 

All this "knowledge" coming from a guy that swore a +94 Caprice could not be bought with an LT1 unless it was an Impala SS. And also swore that you could get a T56 in an Impala SS

Just because YOU never saw one, doesn't mean it doesn't exist.

 

Some winged sprint cars use reverse rotation engines to mainly counter the torque comming out of the corners. Instead of lifting the left(inside curve) tire up, it tries to pull the right side up and improves traction on the left rear!

 

These, "mythical" reverse rotations motors exist. When we rebuilt my dads 1960 Correct Craft Atom Skier (ski boat) we had to get a custom cam made because no one else made it anymore.

1960 AMC Marine 250ci v8 big block. Reverse rotation. Single side draft carb. 138hp and 270lb/ft torque.