340 crank- standard or reverse rotation?

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leyestone

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Hi, I was told that this 340 crankshaft was a reverse rotation one and was wondering if anyone could help me figure out if it is or not. I've read that the only way to tell is by looking at the direction of the oil guides for the rear main seal, I posted a picture of them. The crankshaft also has some markings that say "R2 R3 R4", I'm thinking maybe the R stands for reverse? Any help would be appreciated
-Leandra

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The only applications I ever heard of for reverse rotation were for marine use with two motors.
Hard to imagine, but I am thinking a boat with two inboard 340s would be a ridiculous amount of fun, and now I want to go water skiing.
 
Boats don't have to be twins to be reversed. You will find some single inboards with reversed. If you have the complete engine, the distributor has a big extended thrust bearing adaptor for the distributor. I can't tell from your photo what I'm looking at......no perspective, but what I see there suggests EDIT LOL reverse rotation
 
I have the motor all taken apart, the guy who sold it to me had pieced it together with a bunch of mismatched parts so I decided to just part it out and buy another. I took the pictures facing what would be the front of the motor, like if I was standing in front of the car looking at it.
 
Did you measure main and journal diameters? The R2-3-4 MAY mean they were under size....not super positive about this, just a thought
 
The cam handles all the reverse rotation duties, and of course the starter followed by the dizzy. The only possible difference in the crank,could be in the areas you pointed out. And yours, at the rear mainseal does look reversed.
I wonder what the firing order would be; 1-3-4-8-6-2-7-5? Sheesk, IDK
I worked at a marine shop for a few years. I saw a lotta reverse rotation inboards. Mostly Gms, under the Mercruiser Banner.A think I saw a teener now and then, but I know I never saw a 340. I wouldda remembered that; wouldn't I?
 
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That's a reverse rotation marine crank, the serrations go the other way on an automotive crank.
 
I wonder what the firing order would be; 1-3-4-8-6-2-7-5?

No it's simply the same firing order read backwards, IE 27563481

Then put the 1 in front as that's what you start with so it's 12756348

This is chev, same thing. NOTE In the marine world, "LH rotation" is "normal car" so "RH rotation" is reversed from automotive

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Thanks for the info, I know next to nothing about the Marine engines and wanted to be sure what it was before posting it up for sale
 
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