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Fast road cam in a marine application (reversion)

Old 11-10-2020, 04:59 PM
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Default Fast road cam in a marine application (reversion)

Hi all
im running a 5.7 Mercruiser v8 in my 22ft speed boat, power is around 250hp and she hits 60mph gps with a 23p prop and Yamaha leg ratio about 1.8
Iím on a budget and been offered a cheap 400hp v8 from a car.
I didnít fancy pulling cam and all the stuff that goes with it, so Iím wondering if a road cam (not sure of the cam spec, but I know itís not a truck or Rev application) would work ok without any water being pulled back with the stock Mercruiser manifolds and risers.
Thanks for your time and input in advance
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Old 11-10-2020, 05:28 PM
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Might, or might not. You need to know cam specs, or it will be a blind guess at best.
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Old 11-10-2020, 09:32 PM
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What Underpsi68 said ... you really need to know more detail. Also some exhaust setups will prevent reversion better than others. As a VERY general rule, lobe separation on a lot of cams chosen with preventing reversion in mind tend to be 112 degrees or more ... BUT there really are more details to be considered. It shouldn't be too hard to get cam specs unless they are custom grinds and paperwork is lost ... good luck!
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Old 11-10-2020, 09:44 PM
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Originally Posted by Morris1019 View Post
Hi all
im running a 5.7 Mercruiser v8 in my 22ft speed boat, power is around 250hp and she hits 60mph gps with a 23p prop and Yamaha leg ratio about 1.8
Iím on a budget and been offered a cheap 400hp v8 from a car.
I didnít fancy pulling cam and all the stuff that goes with it, so Iím wondering if a road cam (not sure of the cam spec, but I know itís not a truck or Rev application) would work ok without any water being pulled back with the stock Mercruiser manifolds and risers.
Thanks for your time and input in advance
This never ends well...
What is wrong with the original 350? Why are you replacing it with an unknown asset?
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Old 11-11-2020, 03:19 AM
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Chances are if its a hot rod engine out of a car, which almost all SBC 400's were, it will revert water.
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Old 11-11-2020, 09:09 AM
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Originally Posted by Griff View Post
Chances are if its a hot rod engine out of a car, which almost all SBC 400's were, it will revert water.
unless i read it wrong the op said a 400hp engine but did not state what cu in the engine is.
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Old 11-11-2020, 01:40 PM
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It’s still a 5.7 350 ci V8 with 400bhp
has modified heads, cam, intake, Holley carb etc.
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Old 11-11-2020, 02:51 PM
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3/4 road cam maybe ?
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Old 11-11-2020, 02:53 PM
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Pssst: I'm just playin' OP. Not ennough info. We need cam part # and/or specs . What size and who's V8. That was not even mentioned, so figured I'd add a laugh or two.
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Old 11-11-2020, 03:10 PM
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A 5.7l with large enough cam to make 400hp is going to revert h20 with stock merc exhaust.
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