454 reverse rotation? can it go on the road? - Chevelle Tech
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post #1 of 15 (permalink) Old Oct 1st, 08, 7:18 PM Thread Starter
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454 reverse rotation? can it go on the road?

we got our hands on a 454, 3999289 [454.......71-79...2 or 4 bolt, some "CE" replacement blocks had four bolt main caps]

suffix code"4XB" [1984-Marine-454-230hp- LE-8 ]

It is a marine engine, We are not sure if it is reverse rotation, and we plan on spinning the motor by hand while paying attention to the order of opening intake valves to figure out if it is or not.

But, if it is, can it run on the street. Obviously we would put a normal starter on it and spin it the correct standard direction. Also would swap out the cam. But will the crank spin either way? I think ive noticed in the past that the counter weights on a crank arent perfectly symmetrical, which makes me worry.

also thought id add on the intake, where it says "firing order", and lists the order, it has been ground off. Thing is, i dont know if it said the standard chevy firing order and that was gorund off, or if it read the reverse order
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post #2 of 15 (permalink) Old Oct 1st, 08, 7:33 PM
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Re: 454 reverse rotation? can it go on the road?

I can't remember for sure but I think the reverse rotation engine will have timing gears to turn the camshaft the opposite direction instead of a timing chain.
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post #3 of 15 (permalink) Old Oct 1st, 08, 7:34 PM
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Re: 454 reverse rotation? can it go on the road?

I have one in my car, cam must be changed as well as the rear main seal!!!!!!!!!!!!!
The seal has sipes in it that direct oil "in" as the crank rotates so the seals are made LH & RH
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post #4 of 15 (permalink) Old Oct 1st, 08, 7:37 PM
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Re: 454 reverse rotation? can it go on the road?

Marine engines could be set up to spin the opposite direction--but--more often the reversed propeller rotation is done with gearing not engine rotation.

Having the firing order ground off of the manifold does give a guy reason to think, though.

I'd be looking at the rear main seal and the sealing surface of the crank shaft; the seal is probably different than what is used on a regular-rotation engine in that the tiny molded-in "hash marks" on the seal will be in the reverse direction from a regular seal.

I'd expect a reverse-rotation engine to use a two-gear timing gear set rather than a two-sprocket and chain system--but that isn't a certainty.

The big question: is the water jacket of the block and heads totally corroded from lack of antifreeze and possible saltwater use?
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post #5 of 15 (permalink) Old Oct 1st, 08, 11:22 PM
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Re: 454 reverse rotation? can it go on the road?

Everything is the same on BBC reverse rotation engines, EXCEPT the cam (two gear drive, so it turns opposite), crankshaft seals and starter. All other parts, including the crankshaft are the same as "normal" rotation engines. It is common for the firing order to be ground off the intake manifold, as the intake is the same for normal and reverse rotation engines.

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post #6 of 15 (permalink) Old Oct 2nd, 08, 1:05 AM
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Re: 454 reverse rotation? can it go on the road?

It would be a good idea to have the crank polished in the correct direction, although if it has many hours on it that shouldn't be an issue.

When a crank is polished, it is done so in a specific direction to lay the surface texture (like microscopic fish scales) so it goes with the direction of crank rotation. Anyone who's installed a freshly polished crank with relatively tight bearing clearances and then rotated the crank has found that the crank spins easily clockwise but will feel like it locks up when spun backwards. (a bad thing to do regardless) This becomes less of an issue with forged cranks, and even less so with H bearings and looser clearances.
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post #7 of 15 (permalink) Old Oct 2nd, 08, 1:06 AM
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Re: 454 reverse rotation? can it go on the road?

Quote:
Originally Posted by engineguy View Post
Everything is the same on BBC reverse rotation engines, EXCEPT the cam (two gear drive, so it turns opposite),
I'm having some trouble picturing the cam timing events vs. crankshaft position.

If the crankshaft spins the opposite direction...and the cam drive uses two gears...does the camshaft have to be different? It's spinning the normal direction. Similarly, the distributor and oil pump should spin the normal direction, too, and without special gears on the back of the cam and at the bottom of the distributor.

The firing order would certainly be different; and the major and minor thrust surfaces switch places--but--I'm thinking that all 8 of the pistons come "up" at the appropriate time to match the valve timing.

Pistons would have the pin offset in the "wrong" direction for quietness; but supposedly reversing the offset slightly improves power output, so not everyone would object. And of course not all pistons have a pin offset; those that don't would be just as happy with the crank going either direction.

Am I thinking clearly about this???
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post #8 of 15 (permalink) Old Oct 2nd, 08, 1:32 AM
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Re: 454 reverse rotation? can it go on the road?

Cam spins in the normal direction because of the two gears, but the lobes are in different places to match the different firing order. Crank seals are different as mentioned. Starter was always removed by the installer by the time I got the engine, but it make sense that it would have to turn the other direction to move the crank that way.
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post #9 of 15 (permalink) Old Oct 2nd, 08, 10:04 AM
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Re: 454 reverse rotation? can it go on the road?

"If the crankshaft spins the opposite direction...and the cam drive uses two gears...does the camshaft have to be different? It's spinning the normal direction."

Due to the two gear drive, the cam is rotating in the opposite direction. Therefore a special cam needs to be used, otherwise the opening and closing ramps would not be correct, as well as opening/closing valve events.

Bill
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post #10 of 15 (permalink) Old Oct 2nd, 08, 10:13 AM
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Talking Re: 454 reverse rotation? can it go on the road?

You will have to use Oil made for reverse rotation engines, I can get you sum but its not sold over the counter. You will also need a reverse rotation berring on your camshaft and an reverse offset rotaion bering on the crankshaft to off set the reverse rotation of the marine engine to make it spin the correct or opsite rotation of the reverse its now spinning!
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post #11 of 15 (permalink) Old Oct 2nd, 08, 10:25 AM
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Re: 454 reverse rotation? can it go on the road?

Ken,
It is perfectly clear now why you have crazy in front of chevelleman!

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post #12 of 15 (permalink) Old Oct 2nd, 08, 10:44 AM
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Re: 454 reverse rotation? can it go on the road?

The reverse Rotation engine all the diffrent between std rotation engine is the Camshaft and Dist gear and Starter.
The dist gear on the cam is cut backward so the oil pump and firing order still be standard rotation.
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post #13 of 15 (permalink) Old Oct 2nd, 08, 11:30 AM Thread Starter
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Re: 454 reverse rotation? can it go on the road?

Quote:
Originally Posted by crazychevelleman View Post
You will have to use Oil made for reverse rotation engines, I can get you sum but its not sold over the counter. You will also need a reverse rotation berring on your camshaft and an reverse offset rotaion bering on the crankshaft to off set the reverse rotation of the marine engine to make it spin the correct or opsite rotation of the reverse its now spinning!
was that supposed to be funny
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post #14 of 15 (permalink) Old Oct 2nd, 08, 7:12 PM
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Re: 454 reverse rotation? can it go on the road?

Quote:
Originally Posted by Rick T View Post
was that supposed to be funny
Yes, I was in a good joking mood this moring and figured I would throw sum humor in. Seems that you may have been ofended, if so I am verry sorry didnt mean anything personal.
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post #15 of 15 (permalink) Old Oct 2nd, 08, 8:16 PM
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Re: 454 reverse rotation? can it go on the road?

Quote:
Originally Posted by speedracer77 View Post
Cam spins in the normal direction because of the two gears, but the lobes are in different places to match the different firing order.
Yeah, I'll accept that. Thanks.

Quote:
Originally Posted by engineguy View Post
"If the crankshaft spins the opposite direction...and the cam drive uses two gears...does the camshaft have to be different? It's spinning the normal direction."

Due to the two gear drive, the cam is rotating in the opposite direction. Therefore a special cam needs to be used, otherwise the opening and closing ramps would not be correct, as well as opening/closing valve events.
No, the cam isn't spinning in the opposite direction from a "normal" engine.

In a normal "regular rotation" engine, the camshaft and the crankshaft spin the same direction--both turn clockwise viewed from the front.

A two-gear drive spins the camshaft the opposite direction from the crank. So a regular rotation engine would have the crank spinning clockwise just like normal, and the cam spinning counter-clockwise because it turns backwards with a two-gear cam drive system.

But a reverse-rotation engine has the crank spinning counter clockwise, and with a two-gear cam drive--the cam spins clockwise. Just like a "normal" engine. No special gears needed on the back of the cam or on the distributor, because the cam is turning opposite the crank--but the crank is running backwards.
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