fiero377ci

ok i found a 350 that came out of a dual motor boat, it runs backwards would this be a drop in and go for my brothers 82 4 speed. im so gonna get him good, i told him "found ya a motor, its got at least 400 horse lol"
the reason im feeling real mean is b/c he junked my 70 c10, 82 s10 set up for chevy, cheetah shifter, etc etc, 87 fiero, 89 rs vert, sure it needed floors and all but still. so all b/c im off in the navy he figures he can get away with it. well illl be nice and get him a motor for that lol

camaronewbie

I'm pretty sure GM never produced a "reverse rotation" boat engine. There are a few weird reverse engines in the world that were produced, but not from GM (Volvo-Penta and other marine-specific engines). The reverse marine engine from GM is a myth. ALL SBC are all the same.

Turbok9

If this came out of a twin powered I/O or inboard, it may not be reverse rotation depending on where you got the info. Usually the reverse rotation of the screw (propeller) is handled by the outdrive on an I/O or the gearbox on an inboard, not by the engine itself. The whole purpose is to eliminate torque steer at the screw, and it's cheaper and easier to do it with the outdrive or gearbox than building a unique motor. Although, they do exist.

Now... why do you want to drive around backwards again??

Apeiron

Mercruiser made tons of reverse-rotation SBCs.

camaronewbie

OK - didn't know - thought I'd read alot of posts here over the years stating that all SBC rotated the same.

So what makes it spin backwards?

five7kid

iTrader: (14)

The starter.

Of course, the cam and distributor are modified to keep it running.

camaronewbie

I figured must be cam/timing changes.

Starter ... yeah, that's one of those things that's so simple that I didn't even think about I'm always trying to make things more complicated that what they are.

Turbok9

You can actually start and run most manual tranny carbed cars with the engine running in reverse rotation.... just pop the clutch while she's rolling backwards with the tranny in reverse. It'll run like crap as the timing will be retarded rather than advanced for most, but 9 out of 10 will start and run.

Gotta make surethe throttle plate is open.

Apeiron

Not too likely unless your car is a 2 stroke diesel.

Turbok9

Try it sometime. Why would it not run? Diesel? What makes you think the plugs won't fire on a gas engine? Even with without alt current you have a battery. Distributor doesn't care, it's just closing circuits as it spins backwards, as it does forward. Air flow and vac are the same. The exaust stroke is still the exaust stroke etc....

We did this a few years ago with an old Toyota Celica on a bet. Ran for a couple seconds and wasn't drivable, but it ran.

Apeiron

Airflow and vacuum are hardly the same on a four-stroke engine running backwards.

EastBoundNDown

Exactly. Four stroke engine go suck, squeeze, bang, blow. Think about that process, and you'll realize why it can't happen in reverse. Only 2-strokes will run backwards. Four strokes need a reconfigured cam that puts things in the right order.

GMan 3MT

iTrader: (4)

Wait, what? Maybe I'm misunderstanding you. With the car off, I've popped the clutch with the tranny in reverse many times when rolling off the trailer to start it. The engine is NOT turning backwards. Maybe if you're rolling backwards and drop the clutch in 3rd (or another forward gear).

sofakingdom

iTrader: (1)

I have NEVER IN ALL MY DAYS seen a Merc motor that ran in reverse.

Anybody that's ever worked on an outdrive will know why. In those, there is no functional difference whatsoever between forward and reverse; you just put a different prop on them.

For that matter, the same thing applies to inboards; the Velvet Drive or V-Drive, and the prop, takes care of it.

Virtually ALL boat motors made in the last 75 years or so are normal rotation because of the way boat transmissions are made.

Before jumping to that HIGHLY UNLIKELY conclusion, I'd make sure about that.

Turbok9

Heh. If the car is in reverse it has to go forward. If the car is in 1st it has to go backwards.

As for airflow and vacuum and suck blow etc, the pistons go up down up down and suck and blow yes. And the plugs fire at the just the opposite side of the cobustion stroke. They draw in air the same way they do running properly and expel it the same way. Up down not round and round. Think about it. The timing of the plug firing is simply retarded, which is why it'll run like crap. It isn't blowing out air on the intake and sucking air on the exhaust, LOL. It's still taking air in the intake and out the exaust valves as it should, the timing is simply off, and on an engine where the timing is measured in just a few degrees, it's not far off. It's like a non-interference engine that's jumped a few teeth on the timing chain, but not quite enough to kill it.

Which is why, to make a reverse run engine run well, you need a 'reversed' cam and flip the ignition timing. The reason they don't use 'em for marine use like people think is because marine engines break. Lot cheaper on maintenance and parts and easier to produce if you really on the outdrive gearing.

On that note, I have seen reverse run Mercruiser 470's, and that's all it was was a 470 with a wacky cam and some other minor changes. Not FROM Merc, mind you, but modded for Rat motors. Same heads, same crank, same etc etc etc. Basically the cam and ignition timing simply reverse the sequence of valve and spark, which seems like a major deal, until you realize that all that means is timing each event to the proper side of each up or down stroke. IE if your firing order is 1-2-3-4 than running backwards of course it's 4-3-2-1, and that is what it does with a stock cam / ignition except the timing is on the wrong side of the stroke. So yes, older carbed engines can fire like this. Everyone here I'm sure that has done any major engine work has had the experience of watching a grossly out of time engine struggle and sputter and shake... same thing.
Bet none of you running around waving your arms over your head saying it's impossible or 'not likely' have grabbed an older carburated car, propped the throttle plate open, and tried it yet...

Turbok9

Different prop?

OK so I have a standard rotation outdrive and I put a reverse pitch prop on it? What? That would make the prop PULL the boat rather than push it.

Yes, there ARE reverse outdrives, heck, even the Alpha One comes in counter rotation and they are quite common on twin engine boats. Do you work on outdrives? I hope not, unless you are inland and away from the ocean where you find most twin screw boats.... And yes, a counter rotation drive uses a reverse pitch prop.

Don't believe me? Go to sterndrives.com and look for 'em.

Apeiron

No they don't. Spin it in reverse and it sucks from the exhaust and blows into the intake.

You can not make a four-stroke engine run opposite to its designed direction.

Apeiron

Think twin-engine, twin-prop. They counter-rotate.

fiero377ci

so were trying to figure if it actually runs reverse or if its in the trans. my buddy whos 70 swears it does in fact run reverse i guess if it dosnt my retard brother will have a good running motor. i already called the junkyard he took em to and told them they were all stolen, there not crushed yet so hes putting them aside. i told him ill make my brother pay him back, and if he dosn't then press charges. but i told him hes wrong for takin them w no titles in the first place. he said he took them b/c he knows my dad so well. my brother has dropped c4 on every bridge he ever had lol

Turbok9

OK you guys are no fun. I was hoping somebody would actually try it. Some times it's fun to be a (insert explitive here).

:-D

sofakingdom

iTrader: (1)

No the Alpha One DOES NOT "come in reverse rotation". All you do to make one "reverse", is hook the shifter cable up the other way. Then of course put a prop that goes the other way on it.

Yes I know about twin-engine twin-prop boats. BTDT.

http://www.sterndrive.info/alpha-one...ing_lower.html

The way an outdrive works is, there's a shifting dog (part # 53 in the dwg) that sildes along the prop shaft, with one-way teeth that mate up against either of 2 "ring" gears that are driven by the "pinion" on the vertical shaft. The 2 "ring" gears, being on opposite sides of the "pinion", rotate opoosite ways when viewd from the same end. If the dog is up against the one "ring" gear, the shaft goes one way, and you put a right-hand prop on the shaft to go forward; if it's up against the other, it goes the other way, and you put a LH prop on the shaft to make it go forward. Boats are simply set up with their shifter cables pushing the linkage one way or the other, depending on which direction the shaft needs to rotate for "forward".

It's just WAY too simple. For basically ZERO cost and NO parts being different AT ALL, they get the job done; no need to worry about cams, distributors, starters, water pumps, oil pumps, power steering pumps, and whatever all else, that would have to go backwards if the engine turned the other way. Boat motors don't run backwards. That whole idea is just ignorant, one of those ancient myths that might have been true in some cases at one time, but no longer is; but JUST WON'T DIE anyway. Perpetuated by people who have never worked on boats.

http://www.perfprotech.com/store/app...ift-adjust.pdf

Here's how the shift cables work.

five7kid

iTrader: (14)

Googled "reverse rotation chev engine". Some of the hits:
http://www.chevy350motor.com/Chevy_3...50lmlb-2r.html

http://www.youtube.com/watch?v=eFQm951wb0M

http://www.fastengineparts.com/produ...ew.php?id=1708

http://speedtalk.com/forum/viewtopic...t=7160&start=0

http://www.correctcraftfan.com/forum...verse-rotation
(Interesting discussion about the cam)

Way back when, the U.S. Army had an armored personnel carrier, the M114, that was powered by a Chevy 283. It was reverse rotation. It also had a round bellhousing. And a sealed ignition system. I only saw one of them (they had been phased out by the time I was in the Army).

sofakingdom

iTrader: (1)

Note that those aren't for outdrives.

Turbok9

Keep perusing the site dude. Alpha's are NOT bi-directional. Running them in reverse at WOT over a period of hours will eventually tear them designed to run at WOT under load in one direction. Will it work? Maybe, depending on how brutal you and the sea are on the drives... but I'd NEVER head out into big water with an RH Alpha running as a LH unit.

From the same site... http://www.sterndrives.com/mercruisersterndrives.html
Look for the bit about "Not all drives can counter rotate".

Sorry gotta go. Gotta put new impellers in my Grady. ;-) Nope, never work on lower units...

fiero377ci

so what im getting is that they were never made. if its a guarantee to be a standard rotation its goin in another dime me thinks.

91phoenix

iTrader: (5)

I have heard of a few reverse rotation chevys in a mid type engine boat with a staged pump jet drive. However most of those staged pump jets were running a chrysler motor. Yes there is such an animal but they went out of favor in the early 70's. There may have been a few lingerers but not many in the boats.

t-top havoc

iTrader: (3)

Gotta love your brother!! LOL!!
Thank You For Your Service!!!

sofakingdom

iTrader: (1)

Yeah there are VERY VERY FEW such things left in the world... way too much trouble and expense to fool around with altering the motor when it's SO EASY to make the transmission do the job.

As shown in the drawings and instructions I posted, as well as by parts lists that only show 1 part # for each part and don't even mention direction of rotation, there's no such thing as a "RH" or "LH" outdrive in modern times except after it's mounted on a boat. Anybody THAT WORKS ON BOATS would know that.

And, as also shown in the link the above poster put up to try to prove .... something .... Iunno, that he doesn't know what he's talking about, I guess .... here's the quote from right above that:

(looking at it from the point of view of the drive, i.e. the flywheel end of the crank)

And that same link further down talks about how on drives that DO counter-rotate, the LH and RH drives are IDENTICAL, just the shifter cables are set up different.

Which, as anyone familiar with Merc outdrives would know evidently unlike the guy that posted it, the inability of older drives to rotate in reverse under power for extended periods of time is a consequence of how the gears in the lower unit were cut.

So yeah, to the OP, I wouldn't be too terribly concerned about the possibility of a backwards-rotating motor. While maybe not impossible, the probability of running across such a thing is EXTREMELY remote.

All of which reminds me, it's about time of the year to get up off my lazy butt and go outside and take the lower unit off of my Merc outdrive and change out the water pump.... fortunately it doesn't need new gears in the lower unit AGAIN, I've gone through an uncomfortable # of those in days gone by. Jut some routine maintenance.

five7kid

iTrader: (14)

I was only addressing the speculation that there never was such a thing as a reverse rotation SBC, not what they may have been put in.

I've never owned a hole in the water into which money is poured, so I don't much keep up with what's going on in that cult.

sofakingdom

iTrader: (1)

Yup, that would be it...

Although, I wasn't offended by your comments, it was those others that were rather un-called-for.

Turbok9

A Bravo drive and an Alpha drive are two very different beasties. Reading is fundamental. Yay.

Not saying you'd do this sort of thing, but you sound just like the guys who like to talk about how there is no diffence between a marine and an automotive fuel pump or coil. They talk and believe and convince others the best they can until someone listens to them and gets killed because their boat burst into flames nine miles out to see...

You know when you rebuild the internals on an Alpha you allow for 1/16th" to 1/8th" play in the shaft right? You know of the LH drive you don't... in order for that to happen the lower unit is slightly difeerent. Why? Because when you are essentially running the boat in reverse, you are driving the prop shaft from below on what is intended to be the reverse gear originally. Nothing to do with how the gears are cut, Alpha drives are not 'older drives', Bravo drives are not 'newer' drives. Bravo drives are for bigger boats and higher power needs, and are a larger, bulkier, stronger drive. Two different animals.

Oh forget it. You obviously aren't going to listen... that's obvious by the last post you made... You are offended? Whatever. This from the guy who makes comments like "anyone who works on outdrives would know" and "evidently unlike the guy that posted it,".... Pretty funny and ironic I'd say. Anyway, have fun with your drive... Although you may have a tough time finding a "water pump" inside your lower unit, since all it is is a rubber impeller with a plastic housing...

boatingbound

I service 2 Searay 32' twin engine boats in the marina where i live and they both have ports engines that rotate opposite of the starboard both are 350 chev 1 is a 1986 and the other an 1989

novaderrik

read the first few posts, skipped to the bottom to post.. so this might have been covered already...

a reverse rotation small block uses a gear drive with no idler to turn the camshaft the opposite direction as the crank.. in other words, the cam, distributor, and oil pump all run in the "proper" direction, with only the crank, rods, and pistons turning "backwards".. you can use a reverse rotation marine engine in a car by putting a regular timing chain in it and bolting up a regular starter.

sofakingdom

iTrader: (1)

So, n00b REGISTERS, just to resurrect this from the dead and post this... yeah.

Which of course is exactly opposite from MERC'S OWN MANUALS. (or, the aftermarket replacements, which was the only one I could find a blowup of, that I posted up there)

Merc never supplied an outdrive motor with a gear drive. The motors all run the same way.

I don't believe it.

I'm lazy, or I'd go outside and tear down my own outdrive (for not the first time I assure you) and take pics that show how it works.

bigal55

iTrader: (1)

So what you're saying is the firing order (determined by the distributor and cam) would remain the same if the engine were turned backwards?

Joe Tag

iTrader: (4)

The only way it would work is a special ground cam. If you run the crank in reverse, the firing order would be reversed( not just determined by cam and dizzy, piston position has a lot to do with it)
Not to mention, the drive gears would be too large to fit in the timing cover without an idler.
Edit: now that I think about it, you would have the oil pump turning in reverse too. You would need reverse cut drive gears for the dizzy to turn the pump the right way, or a specialty pump.This is wrong on so many levels, I cant wrap my head around it.

novaderrik

google found me this:

http://www.promarengine.com/marine.asp

454, standard rotation:



454, reverse rotation:



small blocks will be the same way, only slightly smaller..

the cam turns the same direction in both engines, which means that the distributor and oil pump also turn in the same direction in both engines... and due to the crank being ground the way it is, the firing order would be reversed..

Joe Tag

iTrader: (4)

http://www.ebay.com/itm/Mercruiser-r...-/300949000847
Apparently, the gears are still available. I stand corrected. I pictured them being larger because the timing gear does not have much room in a standard rotation. No longer a myth, seems to be a solid fact. Listing says it was off a 1987 merc.

Joe Tag

iTrader: (4)

But wait..... there's more. Here's a reverse cut distributor gear. So apparently I wasn't so far off. They do it both ways, chain and gear drive.
http://www.ebay.com/itm/COMP-Cams-Re...-/271258122064

Atilla the Fun

If the car has a really old 4-speed, get under the car and change the shift linkage around, so first and reverse are switched.

More-Gears

You maybe right but, GM (and Ford before) has contracts with major marine engine builders to do just the opposite.
Sorry, don't mean to step in any toes here but,

Gear to Cams are made everyday without a Dog bone and work awesome backward or forward (LH or RH)!
So, a reverse cam grind is very common and would allow the engine to run backwards or forwards too
I like the gear to gear, rather than a noisy dog bone.

More-Gears

You maybe right but, GM (and Ford before) has contracts with major marine engine builders to do just the opposite.
Sorry, don't mean to step in any toes here but,

Gear to Cams are made everyday without a Dog bone and work awesome backward or forward (LH or RH)!
So, a reverse cam grind is very common and would allow the engine to run backwards or forwards too
I like the gear to gear, rather than a noisy dog bone.
Great Idea! Wish I could of F-d up My brother the same way!! Yup, he's done worse!