Hi, I have got a 360 bare block that I'm starting to think is or was a reverse rotation marine one, the bore size is +.025", that is weird enough, the stamped # on the front of the block is 5 or 6 numbers stamped vertically instead of just under the deck. What has pointed me to marine is the bore wear, what little of it there is, is on the minor thrust side of the bore. Anyone had experience with this stuff ,and if so are there any other differences that would preclude using it as normal rotation ? Thanks .
Marine 360?
- Thread starter raymond
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Sure sounds like it. As for the bare block, there are no differences that would stop you from using it. The crankshaft is an entirely different animal.
dodge71demon
Well-Known Member
I've been wrong many times before but I believe the crank is the same except that it may not be drilled for a pilot bushing the main difference on the short block is in the camshaft so the block is the same for marine or automotive use check it out real good was it used in salt water or froze due to no antifreeze
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well if it is a marine Reverse rotation crank it is different than a standard rotation one . a R R crank is ground different on the rear main journal , using one in a standard rotation will result in a constant oil leak at the rear seal .
OK I kind of went through this with a 440. Crank is the same needs to be re polished or the rear seal will leak, camshaft is opposite what it should be so that needs to be changed, distrib needs to be changed. Oil pan and exhaust manifolds are different as well as the water pump. Hope it helps.
You could be the fastest guy in reverse.... 
No idea mine was standard bore but as I said a 440. Tell you what it can run!
Aggree. I heard an engine builder mention that the knurling at the rear main on the crank would actually draw the oil out, instead of keeping it inside the rear main, if you changed the rotation.
Also with marine engine look for major rust in cooling jackets. If it was raw water cooled salt or plain water (lake water) was run and eats the jackets away from the inside. Just a heads up. All the boats I’ve stripped for Mopar engines (they were popular on the 70’s) the Reverse rotation engine cranks some were different and a few were same as stock rotation. You had to run number to figure it out. All the high end boats I dug thru to get the engines, had different cranks. The cheaper brand boats had standard rotation cranks. Possibly due to balance was smoother at 2800 rpm - cruise on plane speed. Not high rpm at all.
RIBOATSERVICES
Well-Known Member
Hellrats
Just another dumbass
I thought boat engines were standard rotation unless it had two engines. Then the second engine went the other way. So one went clockwise and the second one went counter-clockwise. Interesting.
RIBOATSERVICES
Well-Known Member
You are correct.
The older Correct Craft boats were reverse rotation. One engine, think ski boats. Not sure why.
Mainly if the raw water is salt water, it is much worse. Makes the cast iron crumble from the water jackets outwards.
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67Dart273
Well-Known Member
Single engine boats ARE NOT ALWAYS standard rotation. I have not gotten a good answer on this. Frankly, I think it's more "we had some reverse engines left over." Way back in my auto parts days, a boat owner sent an inboard into a rebuilder, and it came back, they had not checked, had been changed to standard rotation. Obviously the generator, starter, and water pump were still reverse!!!
The issue is most certainly the crank knurling, and of course the cam can be changed. On a small block, a long special fitting and distributor is used, to counteract the opposite thrust of the dist. drive gear.
The issue is most certainly the crank knurling, and of course the cam can be changed. On a small block, a long special fitting and distributor is used, to counteract the opposite thrust of the dist. drive gear.
That adapter is on the RB reverse also.
67Dart273
Well-Known Member
^^You are right I'd forgotten.......here's the RB version
Distributor help for chrysler 440 marine engine reverse rotation
SB
Distributor help for chrysler 440 marine engine reverse rotation
SB
Daves69
Well-Known Member
Crank oil seal serrations opposite angle on a reverse. Image is a sb reverse from eba......
Free manual download if it helps for the LM318-LM360.........
Engine Data And Specifications - Chrysler LM 318 Service Manual [Page 8] | ManualsLib
I believe a block is a block. Curious, does it have "LM" stamped on it by chance?
Free manual download if it helps for the LM318-LM360.........
Engine Data And Specifications - Chrysler LM 318 Service Manual [Page 8] | ManualsLib
Thanks for that info, it's just a bare block and the only ID I can find on it is '18970' stamped on the front of it.
This ^^^^^ is correct. It was what I was referring to in my first post.
The crankshaft is not the same. The rear main seal area is marked with backwards hash marks compared to a standard rotation crank. You cannot simply "polish" it and go. It requires a standard rotation crank.
That can certainly work, but it makes them more prone to leak.
That's what I did so far so good.
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