SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: GAWnCA on October 04, 2007, 07:13:07 AM
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Now I've got a question and it doesn't concern the engine type or make, so I hope this doesn't become a battle over which engine make is better than the other.
When it comes to boats in general, hot boats to be more specific, when comparing "JET" powered to "V" drive powered motors, is there a difference in the machining processes required? And, the kind of components that may be installed? I.E. Heads, pistons, valves, etc.
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The only diffrence other than mounts and water pump would be cam. And the cam would only be if you wanted to fine tune it.
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A marine engine has slightly larger clearances due to the pistons getting hot and the block staying cool.
As far as the V-drive deal your wife will kill you ;D
In most cases a hot jet will not exceed 6,000rpms ut a hot v-drive will spin 7,200 or so. The gears and prop will determan the camshaft used.
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I hope my wife doesn't find out until it's too late. :)
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A marine engine has slightly larger clearances due to the pistons getting hot and the block staying cool.
How much larger? Only in the bore? What about rod journals and main bearings? I'm getting ready to send my 460
to the machine shop and I want to know what to tell them to do, and what to look for before I pay them for it!
Thanks
Skip
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How much larger? Only in the bore? What about rod journals and main bearings? I'm getting ready to send my 460
to the machine shop and I want to know what to tell them to do, and what to look for before I pay them for it!
Thanks
Skip
bearing clearances should also be a smidge larger (+.0004 or so)or at least on the larger side of the automotive clearance range. Cars can run the tighter clearances due to them very rarely seeing 3000rpms let alone 5. Jets, as you know, very rarely go below 3k and often times are above the 4800 to 5k. Although not completely necessary but a real good set of high performance head gaskets are a good idea....at least that's the way I was taught.
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who is doing your machine work=
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who is doing your machine work=
Hopefully Jim Barnes if I stay local with it, do you have any recommendations?
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How much larger? Only in the bore? What about rod journals and main bearings? I'm getting ready to send my 460
to the machine shop and I want to know what to tell them to do, and what to look for before I pay them for it!
Thanks
Skip
skip the general rule is .001 for every inch of journal, i will talk to you more about this at the races.
fyi, mine is .003 mains and .0025 rods
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skip the general rule is .001 for every inch of journal, i will talk to you more about this at the races.
fyi, mine is .003 mains and .0025 rods
Hey Ralph, Don't be shy :) share the wealth of information with all of us. Greg
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parish automotive =sac town
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Brad] 1:39 pm: i'd do it if i had a fuckin boat
[Brad] 1:40 pm: no time to work on it anymore
[bkplesh] 1:41 pm: take it to jim
[cj410] 1:41 pm: why, so omar can pass brad too
LOLOLOLOLOLOLOLOLOLOLOLOLOLOL....THATS FUNNY SHIZZZ RIGHT THERE...and i dont even know jim !!
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If you have to tell the machineshop how to build it CORRECTLY, you are DOOMED!!!! If they can't tell YOU how to do it, RUN!!!! But then again, you may get lucky. You DO believe in luck dontcha? TIMINATOR