Reverse rotation engine question ...
 

IS there anything different about the pistons and rods in a reverse rotation engine ? Or can you take a standard engine and change the cam , timing, etc .and run it . Are the pistons and rods mounted different ?

A friend did this with a motor and lost the bottom end . We are not sure of the condition of the motor prior trying it . It may have just been no good anyway . But ALL of the bottom end bearings are destroyed exactly the same ......

Re: Reverse rotation engine question ...
 

I would think that the tabs that hold the bearings in place would come from the other direction in a reverse engine.

My friend has one in his fishing boat but he bought it replace the reverse engine that fried.

Re: Reverse rotation engine question ...
 

man i thought you were gonna get your boat running!!!!!

Re: Reverse rotation engine question ...
 

I don't think the rods or pistons are different but the timing cover seal is different and the rear main seal is different on some.

Re: Reverse rotation engine question ...
 

I assume we're talking Chevy's here.

The notches on the side of the pistons
face the rear of the block, instead of the front.
(this changes the pin/thrust offset)

hope this helps.

jt

Re: Reverse rotation engine question ...
 

They did a lot of them when I was at Cruise master the Arneson drives in those days required a reverse rotation engine actually I like that setup better than using a gear set to reverse rotation. I guess you could drive a mechanic crazy by slipping a reverse starter on a standard engine.All kidding aside I also heard the Oil should lead the thrust 60 degrees on the crank so a special drilled crank would be needed But the Builder would know best on this point.

Re: Reverse rotation engine question ...
 

This is right,allso the front and rear seals are different,time gear instead of chain.

Re: Reverse rotation engine question ...
 

four weeks ago we reversed the rotation of one of my engines to get rid of the drop boxes. we had a cam ground with the same specks but in reverse rotation and had the cam gear that drives the oil pump and distributor ground with the opposite angle. then you put a distributor gear on that is ground the opposite angle and the oil pump spins the right way, then you change the fireing order and put the starter on the other side of flywheel and away you go, total cost was $340 lunati custom cam, $27 reverse direction distributor gear, and $70 for next day shipping because i hate to wait.

Re: Reverse rotation engine question ...
 

Thanks for all the info !

I need to know this for a fact ....

I have two, off board sources, that are arguing . One says yes ,one says no .

Please let me know the facts if possible . Thank you very much ! Joe

Steve1 . I like that starter idea ! :D
I have a 1000 that runs reverse in my cat with the arnesons . But it has been on the floor for 3 years now . (as "Outer42" knows :( )I can't remember how it is done ...... :(

Thanks !

Re: Reverse rotation engine question ...
 

Hey Bigyellowcat, You didn't change anything in the bottom end ? What about the seals ?
How much time do you have on them now ? Thanks for your reply ! :cool:

Re: Reverse rotation engine question ...
 

Bigyellow, just wondering, what size motors are they ?

Re: Reverse rotation engine question ...
 

boot bring that boat to me,i'll get it going for you!!!!!!!!!!

Re: Reverse rotation engine question ...
 

Ive got an open, reverse, short block in my shed. Ill look at the pistons and crank tonight to see if the pistons are reversed or if the crank oil holes are different.

Re: Reverse rotation engine question ...
 

NICE !! Thanks for the info !

Re: Reverse rotation engine question ...
 

one thing you need to do is polish the crankshaft in the direction of rotation because when polishing the crank it raises the metal and you do not want your oil flow going against the raised metal. Tyler

Re: Reverse rotation engine question ...
 

Merc and most marine builders reverse their crankshaft rotation but maintain normal cam rotation by using a gear rather than chain drive. That way you can use a standard distributor/oil pump setup. Cam is a different grind. The crankshaft p/n for merc is the same on left vs right rotation, so that doesnt seem to be an issue. Pistons and rods are also the same p/n. I've heard about reversing the pistons on older engines, not sure about that though. Only the rear seal is different, yellow instead of blue. Although there are people on this board using the wrong seal without problems. Front seal is the same.
That being said, Bigyellowcat pointed out you can reverse the rotation of both the crank and cam with a few modifications.
I hope formula31 can shed some light on piston direction.
Gary

Re: Reverse rotation engine question ...
 

You can use a non-directional seal on both.Some seals have groves(yellow/blue,rear main) to keep the oil in the pan .

Re: Reverse rotation engine question ...
 

If you reversed the oil pump, what would that do to it's flow?

Re: Reverse rotation engine question ...
 

you cannot reverse the oil pump it needs to still turn the same direction.

Re: Reverse rotation engine question ...
 

I was wondering if that was why his buddy took out his crank bearings...

Re: Reverse rotation engine question ...
 

Hey ,thanks everyone !
Tyler, thats an interesting thought .... Especially since this motor was actually run opposite first and then changed to be standard rotation with no machining done . Just a cam swap etc.

And thanks for the seal info.

Cord, the oil pump can't go the other way . It will pull oil OUT of the bearings instead of pump it in . The cam gear is special as well as the distributer gear ,so that the distributer still turns normal and that is what turns the oil pump . That much I remember .....

This was sort of a donor motor until the original motor was out of the shop . He thought it would last a little while ..... After reading the receipt from what had been done to this engine at one time , it is really scary !! Especially the part about the crank shaft with the question mark after it .........

We may never know but we are wondering if the bottom end had the wrong bearings in it . The crank is standard , maybe it had under size bearings for some reason . I only say this because ,now it comes out that , NOW they remember when putting it together ,that the crank had play in it when trying to turn it with a pry bar ........... I think that " would leave a mark ".........