ok heres my story : we pulled the motor out of a boat two years ago and ive decided that im going to build it up for car use. since it came out of a twin engined boat,it rotates in the opposite direction of a car motor.would i be able to use the crank or would that not work? ps this may sound like a dumb question,but im young s i am dumb when it comes to this kind of **** thanks in advance,troy
It is doubtful that you'd be able to run it if everything on the motor is running backwards. Everything should run and function okay, however, the problem you're going to run into is whenever you attempt to hook it up to a transmission - unless, of course, if you can find a transmission that spins the opposite way. However, it might be an interesting setup if you could pick up an identical motor and run them side by side in the same frame! You could then theoretically run a gear to gear setup that'd allow it to spin backwards but still function correctly. Now, something like that would be cool!
What model of engine is it? I think on most of those reverse rotation engines the difference in cams is the biggie. Once you know exactly what engine you have check and see if the crankshaft for the marine version is different than the automotive or industrial version. You would probably have to check with someone who refinishes crankshafts for that. The cam would definetly be different and probably the dirstibutor.
It's a wierd question and one that i've never thought about. I think that you could run it clockwise with new rings and barings, plus the correct starter motor set up. I hope some one with more knowlege than me can confirm or refute this. Mm, what about oil and water pumps and cam?
With the prospect of being severly flamed...wouldn't the crank be the same ,regardless of rotation ...isn't it the the cam design/rotation and distributor rotation that determines direction of engine rotation... just curious, now that the question has been asked Stan
smokey yunick used to change the direction of his nascar motors, to get around the rotation problem he flipped the rear axle over
If you are only using the crank, and have it in hand, I'd take it to a machine shop and check it against a automotive unit. I'll bet that they are the same. It would be the cam and possibly the distributor that would have to be sequenced differently. And possibly the oil pump too. But the crank pistons and rods would probably spin in either direction with no changes. That's my guess.
I'm familiar with the Ford FE (390, 427, etc.) marine engines. The only difference in crankshaft in these reverse rotation engines is that the rear seal surface on the crank has the oil control helix groves going in the opposite direction to to automotive engine cranks. These reverse rotation cranks work perfectly in cars if you have the crank grinder remove the 45 degree slits in the main seal area. Those slits are hold-overs from the rope seal era and are not needed with the modern neoprene rear main seals. Steve
The difference is the the cam. Cranks, blocks etc. are the same. Don't know about the oil pump. I've been running a standard rotation marine SBC in my 54 Ford. They come with all kinds of goodies like a windage tray high volume oil pump, HD timing gears and great bottom end torque. Mine was $100 at the junkyard and had zero wear, and has about 35K on it now.
I may not be correct,but how does the crank know any different? The stroke isn't different. Have it balanced,install a correct balancer and flywheel. The big difference to a reverse rotation engine,would surely be the camshaft. Where's Squirrel,we need confirmation. Jeez,i got interrupted while i was typing,man everyone was fast on the response.
I was going to suggest this as well. If the boat motor is in good condition, I'd try to make it work, otherwise start with a car motor core and rebuild
First thing I would do is make sure it does rotate in reverse direction. I have a 330 horse Crusader marine 454 in my 57. It turned in the normal direction. It was one of a pair......
Only one I ever saw was an early hemi - like Michiganer said - the only difference was the backwards angle of the knurls on the rear crank seal.
All V-8 cranks are laid out the same.(with the exception of 180 deg. cranks) The diff is in the cam. You can shuffle the firing order and rotation with the cam. The oil pump,water pump and dist. are different,every thing else should be the same on a CC rotation engine.
I have much experience with Big Block Chevy offshore racing boat engine building. Many of you have hit on "quirks" that are easily fixed for normal use in automotive applications. The first is of course the camshaft and distributor gear. The cam is likely gear driven as well.The next is the rear main seal issue already mentioned with the oil control grooves in the ooposite direction, if not changed, will result in severe oil leak. And also the starter drive selection will also need to be addressed. You didn't mention clearly your intention for use. It was ***umed, I imagine, that you are going to keep the engine for use in the reverse rotation mode, but could also be changed for standard rotation with little trouble. Keeping it reverse rotation,as also mentioned by others would require trannies to match(automatic or straight shift)made to also turn in the opposite direction as the rear end as well. Probably not a real practical choice, but it is feasible. Just depends on what you want and how much work you want to go through....
Pistons may look symetrical, but in reality, the pins are slightly offset. Ever notice the little arrows on top that point to the front? This eliminates piston slap or piston rock. Not distructive but noisy. In a reverse rotation marine motor the arrows usually point to the back. If you simply swap out the cam and starter and run it the normal way you will most certainly have piston slap.
Bib, you stole my thoughts and beat me too it! You got it right about the pistons. Also, don't just flip the pistons, rods around as the rods may be relieved for the large crank fillet. Pistons will need to be swapped around. Timing gear, distributor gear, cam need to be swapped out if running backwards. Rear oil seal and front timing seal needs changed or flipped the other direction for the correct rotation. Water pump? Not sure there. Good luck!
One other point - the crank may have been polished for reverse rotation. There are microscopic edges that are "trailing" when rotated that way so if you want to change the crank back to "normal" rotation it should be repolished. I'm playing with a Honda B18 engine that rotates CCW in normal mode and I'm having it repolished for CW rotation. The guys ar Crane and Honda said I'll tear up the bearings if I don't polish it for the proper rotation.
Make sure its rev rotation first , My last boat had 2 SBC and the rev rotation of the props was performed by the transmissions. Both motors were normal rotation
I just did a reverse rotation 350 chevy and the only difference is the pistons are on the rods with the Notch that points to the front actually pointing towards the flywheel and the camshaft is a gear to gear drive. So the crank runs backwards and the cam turns in normal rotation. The oil pump must turn in normal rotation to make pressure. If you change the cam and put a normal chain set in it it should run. Remember to use a car starter and put the plug wires in the right firing order. You can change the pistons around or leave them on backwards, Smokey Yunick says it will make more torque that way. It may be a little noisey.
Water pump? Most serpentine belt waterpumps run opposite to "V" belt drive waterpumps. Gear-to-gear (not Pete Jackson type drives) rotate cams opposite to crank rotation. Sprocket & Chain rotate cams in same direction. Also, check that your fan blades pull air through the rad, not try to push air forward through the rad. Why DID Smokey run a reverse rotation engine? To keep the left front tire gripping the track surface while cornering on the oval track. He could get "on the hammer" much sooner in the corners than his compe***ors. FWIW>
Never heard of such a thing? Ive polished ****ed up journals in the engine and never had a problem .. Did pay any atteniton to rotation either.. you sure these guys arent just taking your money? Dave
I have seen this before on SBC reverse marince engines and can tell you that if the crank is knurled at the crank seal, the knurling will have been reversed for the reverse rotation engine. Trying to run it standard rotation will act line a little pump and pump the oil through the seal instead of away from it.
After talking to the guys at Honda, I talked to two machine shops and they agreed that the crank should be polished in the direction it will rotate. I didn't have any reason to not believe them.
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