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Reverse rotation change

Old 04-17-2010, 07:47 PM
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Default Reverse rotation change

How do I change a reverse rotation '79 305 Checkmate engine to a standard rot for a Searay? The Searay has cracked block.
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Old 04-17-2010, 07:53 PM
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Change the camshaft to standard rotation cam. Replace timing gears with a timing chain set. Reverse the firing order to 18436572. Technically, you should change the crankshaft seals to standard rotation ones, but I've seen it done without changing the seals with no issues.
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Old 04-17-2010, 09:06 PM
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Distrib gear too??
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Old 04-17-2010, 10:49 PM
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Originally Posted by US1 Fountain View Post
Distrib gear too??
No. The camshaft and distributor turn the standard direction in both engines.
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Old 04-17-2010, 11:14 PM
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So a reverse rotation motor uses timing gears instead of a chain?
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Old 04-17-2010, 11:17 PM
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leave it and make the swich with the drive???
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Old 04-18-2010, 04:59 AM
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My understanding is the crankshaft has the oiling holes drilled in a different place for reverse rotation engines. I've never had one open to look at so I'm just going on what I've been told. So it may be possible that you will need another crank.
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Old 04-18-2010, 07:27 AM
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Originally Posted by US1 Fountain View Post
So a reverse rotation motor uses timing gears instead of a chain?
Yes. The camshaft is directly driven with helical cut gears, that's how the camshaft still turns the standard direction. If the camshaft turned backwards, then the ditributor would turn backwards resulting in the oil pump turning backwards... if the oil pump turned backwards, it would blow bubbles in the oil pan rather than pumping oil.

Originally Posted by Reed Jensen View Post
My understanding is the crankshaft has the oiling holes drilled in a different place for reverse rotation engines. I've never had one open to look at so I'm just going on what I've been told. So it may be possible that you will need another crank.
Not true. Somone told you wrong.
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Old 04-18-2010, 09:03 AM
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Just curious, why was a reverse rotation in a checkmate? I didn't even know checkmates had twin IB boats.
Btw, add a new water pump. Early pumps were directional.
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Old 04-18-2010, 12:40 PM
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I'm with rd - why do you think it is counter rotation?
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