Reverse Rotation

The only difference in a conventional engine and a reverse rotation is the cam shaft is ground mirror image to the standard one, requiring a special cam blank to grind it on, the ignition timing is the opposite direction, and the starter is built with either an extra gear to make the engine turn backwards or else the starter is built with reversed polarity.

 

Thanks Max,

You are saying that I can use the crank shaft with a conventional engine? You know the casing no. is the same with a conventional 350 crank shaft.
Could two Crankshafts with same casting number be different?

Thanks for your answer. Please confirm if the Crank shaft is the same.

 

There are lots of things to consider although the crank itself can work either direction. In fact there are will likely be more than one successful firing order option when making the cam. Remember that the distributor in a SBC drives the oil pump so either a custom or external pump will be required. Water pumps are available with either rotation but you need to use the right one. Your alternator will need to be driven in the correct direction or built to operate properly in reverse and even the belt tensioner on a reverse rotation engine must be constructed differently. Power steering and A/C devices could pose a problem too. The gear angle on transmission gears is direction specific, and there are numerous other factors too. Nothing is impossible but you would need a pretty good reason to justify the cost. An exception might be if you are adding a second engine to a multi-engine vehicle and don't need to drive any accessories. Can you give more details?

 

reverse rotation

jmhollis added in some good points that I failed to cover, mainly the oil pump.
Yes, the crank can run in either direction, as there are several different firing orders, that can be chieved with any engine, example is the 302/5.0 Fords which were built with two different firing orders, yet using the same crank throw design.
I am presuming that from your thread, you have a marine engine that you are thinking about putting into an automobile? Or vise versa?
If you are going to put an auto engine into a boat, other than changing the cam, oil pump, and ignition, if this boat previously had the same engine as you are going to put in, then its a bolt up job.
Most boats that have a reverse rotation engine will have them on the port side, and the starboard engine which will have typical rotation, will drive all the accessories such as your charging system, making it simpler to use standard automotive alternators and such.
Marine engines will have a different cooling system to them than an automobile. You will have a water jacketed exhaust manifold which is fed from the engine discharge, and will be exited out the rear of the boat. The coolant for such systems, the pump draws its water directly from the body of water your craft floats in.
As was also noted by jmhollis, if you are anticipating running a reverse rotation engine in an automobile, you will step into a whole new field of problems, such as he mentioned with the electrical charging system, cooling, auxilary drives etc. Then there is also the matter of setting up a rearend to transfer your power.
Years ago, a few brave souls tried reverse rotation engines in Stock Car racing, and what it amounted to was a lot of money spent for absolutely no gain whatsoever.

 

reverse rotation

jmhollis added in some good points that I failed to cover, mainly the oil pump.
Yes, the crank can run in either direction, as there are several different firing orders, that can be chieved with any engine, example is the 302/5.0 Fords which were built with two different firing orders, yet using the same crank throw design.
I am presuming that from your thread, you have a marine engine that you are thinking about putting into an automobile?
If this is the case, then its basically a matter of changing over to a conventional automotive cam, ignition, oil pump, and cooling system, and the intake setup as well. If this a popular engine, such as a SBC, BBC, SBF, or BBF, then vertually all the parts you will need to use it will be easily obtained.
As an afterthought, you will probably have to change oil pans as well, since marine oil pans are generally not condusive to putting into an auto, due to the design.
Most boats that have a reverse rotation engine will generally have them on the port side, and the starboard engine which will have typical rotation, will drive all the accessories such as your charging system, making it simpler to use standard automotive alternators and such.
Marine engines will have a different cooling system on them than an automobile. You will have a water jacketed exhaust manifold which is fed from the engine discharge, and will be exited out the rear of the boat. The coolant for such systems, the pump draws its water directly from the body of water your craft floats in.
As was also noted by jmhollis, if you are anticipating running a reverse rotation engine in an automobile, you will step into a whole new field of problems, such as he mentioned with the electrical charging system, cooling, auxilary drives etc. Then there is also the matter of setting up a rearend to transfer your power.
Years ago, a few brave souls tried reverse rotation engines in Stock Car racing, and what it amounted to was a lot of money spent for absolutely no gain whatsoever.

 

Dear Max and Jim,

Yes I absolutely understand all the factors which you mentioned.

What I'm going to do is that I'm going to build a conventional rotation engine out of this engine.
The marine engine is just an engine with no accessories.
That means that I'm going to put in it an automobile cam, water pump, intake, alternator bracket, Fuel pump, timing chain, oil pump, etc....

So please note that I'm not going to run it as reverse, and that's why I'm concerned about the crank being useable in a conventional rotation engine.

I just need the block, crank, connecting rods. Is it workable?

Thanks for the advises, and have a nice weekend.

Houman

 

As a general note the alternator won't care which way it's turning. An alternator produces 3 phase power that's rectified and the rotor of the alt. contains the field, not the armiture.

 

One of my thoughts on the alternator was airflow. Some alternators have internal cooling fans that don't work properly if reversed due to curvature of the impeller or angle of slots. You are correct about the electrical properties but there could be more to it than that.

 

Yep, use it.

 

I see dual, counter rotating, marine 354 hemis on ebaY quite often. A pair or those with GMC 671 huffers in a T bucket would make a bodacious Sonic Drive-In cruiser don't you think?!?

 

Hemi with Huffer

One of those huffed Hemis would be enough to command lots of respect at the Sonic Drive In nearest to me. All they have there are ricers with $25K engines that might run neck and neck with a stock Mustang 5.0. But then who knows, hear alot of smak talk but no titles or wads of money on the hood with the ricers.

 

I'm not a regular posted here,+ I don't want to step on any toes,...

But,......
You Guys are Seriously Confused about Marine counter-rotating motors.......

The Only thing that turns backwards in a SBC app. is the Crank,+ the accessorries..........

That's Why the cam is driven by a Gear,+ Not a Chain.............

Cam, Dist., + Oil Pump All turn the Same direction as before........

The Cam Is cut different, but it turns the same direction........

 

What do you know - I learn something every day (as hard as I try not to)!

Thanks!!

 

One of my thoughts on the alternator was airflow. Some alternators have internal cooling fans that don't work properly if reversed due to curvature of the impeller or angle of slots. You are correct about the electrical properties but there could be more to it than that.

Good point! I didn't even think about that. Goes to show what great info comes out. Thanks for bringing that up.

 

Be careful.
I would research it a little more.. You could have oiling issues depending on how the crank is drilled.

This is a quote from Melling:
"CRANKSHAFT - Some of the reverse rotation cranks have the oil holes drilled symmetrically opposite. Check this closely."

 

revers rotation

most current marine engines now turn the same. the counter rotation is acomplished by i marine gear runs in reveverse the other forward.this is also the case in diesel engines, cat cummins perkins. only make the one rotation engine. the reason for counter rotarion is for dual engine boats so they run straigt. some turne in. some turn out. cant remember why i am sure some one out ther will know, i to learn a great deal from this sight and apreciate the oportunity. cliff