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Old 18-02-2011, 09:51   #16
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The technology has been revised in snowmachines, or at least it had before the advent of mandated 4-stroke engines. The reverse "gear" on several machines was a button which simply caused the engine to run backwards. Wonderful technology, and I never heard of a failure. And I thought it was a new idea....
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Old 18-02-2011, 10:05   #17
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The OP is referring to a Chevy V8 "designed" to run backwards.

I worked at a Chevy dealer when a teenager, in the parts department. I recall the 427 truck motor in particular had a camshaft specifically for a reversed engine.

A reverse design cam, and a reversed rotation starter is all it takes to make a v8 that runs "backwards".

Can't say about the transmission, but the rear axle on these trucks were "flipped over" to compensate.

Pretty rare truck not around anymore. But I could see counter rotating engines in a twin engine power boat as reasonable, as described by delmarrey in his post.
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Old 18-02-2011, 10:22   #18
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the cam is the brains/logic of a motor... on a 4 stroke the 'strokes' are the steps in which need to happen correctly, in the right TIME for the motor to work.

stroke 1 is INTAKE, suck air and fuel in
stroke 2 is compression
Stroke 3 is ignition/expansion
stroke 4 is exhaust

if you reversed things then you would be blowing air out the exhaust valve, then a spark would happen but not able to ignite plain air, then... you get the idea

you cant run an engine backwards unless you change a ton of stuff... starting with the cam shaft, then the ignition system...etc...

two strokes and other engines maybe different... but probably not...
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Old 18-02-2011, 10:30   #19
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Two strokes: No camshaft. No problem. Spark timing will be wrong in reverse. Chainsaws and motorbikes will be hard to control....

On a four stroke one presumably cuts the camshaft's distributor/oil pump drive gear the opposite way. Maybe the coolant pump needs a change?
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Old 18-02-2011, 10:48   #20
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Having dealt with and tuned LH motors, the things that are different are the cam, the oil pump, water pump, starter, the firing order and lifter adjustment is backwards. The alternator and water pump">raw water pump doesn't matter either way.

I almost bought a 50' Chriscraft once but found out the LH diesel had been rebuilt due to the same problem as to OP, wrong starter.
So one motor had 200 hours and the other had 3000 hours. This one didn't pump in a bunch water, it hydraulic-ed the cylinders and cracked the liners.
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Old 18-02-2011, 10:49   #21
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Because of rotational thrust, there are other changes. So the cam would bear on the same thrust face as normal.

The distributor drive gear, not the entire assembly. It would be like a mirror image of the standard gear.

The water pump impeller.

Probably the oil pump as well.

Firing order probably wouldn't be 1,8,4,3,6,5,7,2, I'm guessing, 1,2,7,5,6,3,4,8.

So more than I stated earlier, didn't really think in the amount of detail needed.

Ooops, delmarrey beat me to it. I'm going sailing anyway, later.
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Old 19-02-2011, 21:45   #22
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anybody have one that will get up on plane in reverse.
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Old 19-02-2011, 23:02   #23
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anybody have one that will get up on plane in reverse.
Heh. But those open transom sailboats can sometimes fill the cockpit in reverse.
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Old 25-02-2011, 11:56   #24
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Re: Honest, it Wasn't Me

Two-stroke outboards can be fun for this... I know of at least one that, when hot, would restart almost instantly before the starter motor had fully engaged. It'd run a bit rough and the cooling flow would be absent, but people often wouldn't notice until they tried to back away from the dock... and the boat ran right up on shore.
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