383 buildup questions plus a cam choice
#21
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I've been looking over cams and was wondering if anyone had any thoughts on running the Nitrous HP cams - NX276HR specificially - it's got a long exhuast duration which I would think would help with a restrictive exhaust setup, and a wide lobe center that should help with reversion....
SPECS::
Basic Operating RPM Range: 2,000-6,000
Duration at 050 inch Lift: 224 int./236 exh.
Advertised Duration: 276 int./288 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.502 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.520 in.
Lobe Separation (degrees): 113
SPECS::
Basic Operating RPM Range: 2,000-6,000
Duration at 050 inch Lift: 224 int./236 exh.
Advertised Duration: 276 int./288 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.502 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.520 in.
Lobe Separation (degrees): 113
For ex... My AFR heads have a very good I/E ratio and the best power is usually made with cams with only 1-2* favoring the exhaust. Ex 224/226. Except in a marine application our manifolds don't flow as well as long tube headers and a little more exhaust duration is needed.
#22
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I have a question since were on the subject of a 383 conversion. How much can you get out of a 350 block? Is 383 the most you can get without honing anything?
#23
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A couple questions - the Sportsman II heads - did you run them "out of the box" or did you buy them bare and add components (valves mainly)
What type/brand of piston did you use?
Are you getting any detonation with the compression you're running? Mine should be real close as I've got -18cc pistons and 64cc heads (82cc vs 84cc volume in the chamber+piston)
I've been looking over cams and was wondering if anyone had any thoughts on running the Nitrous HP cams - NX276HR specificially - it's got a long exhuast duration which I would think would help with a restrictive exhaust setup, and a wide lobe center that should help with reversion....
SPECS::
Basic Operating RPM Range: 2,000-6,000
Duration at 050 inch Lift: 224 int./236 exh.
Advertised Duration: 276 int./288 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.502 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.520 in.
Lobe Separation (degrees): 113
What type/brand of piston did you use?
Are you getting any detonation with the compression you're running? Mine should be real close as I've got -18cc pistons and 64cc heads (82cc vs 84cc volume in the chamber+piston)
I've been looking over cams and was wondering if anyone had any thoughts on running the Nitrous HP cams - NX276HR specificially - it's got a long exhuast duration which I would think would help with a restrictive exhaust setup, and a wide lobe center that should help with reversion....
SPECS::
Basic Operating RPM Range: 2,000-6,000
Duration at 050 inch Lift: 224 int./236 exh.
Advertised Duration: 276 int./288 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.502 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.520 in.
Lobe Separation (degrees): 113
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#24
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#25
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You can take a 350 block out to 396ci using a .030" bore and a 3.875" stroke. That's about the biggest I would want to go.
A few have stuffed a 4.000" stroke crank in to get over 400ci but it does not leave much compression height on the pistons for a marine application.
#26
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dont do all that work to the engine then leave stock exhaust even if you have to go through the prop.......I switched to polished Revolution Marines and on bone stock 350 carb engines and saw immeadiate noticeable torque increase right out of the hole and another 500 or so rpm on top.....they are a direct replacement for stock.......plus I took 100 lbs a side off the back of the boat, 200 lbs total!!.......I would think you would see even more gains on your hopped up engine.......doug
Last edited by pullmytrigger; 12-09-2007 at 10:25 AM.
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dont do all that work to the engine then leave stock exhaust even if you have to go through the prop.......I switched to polished Revolution Marines and on bone stock 350 carb engines and saw immeadiate noticeable torque increase right out of the hole and another 500 or so rpm on top.....they are a direct replacement for stock.......plus I took 100 lbs a side off the back of the boat, 200 lbs total!!.......I would think you would see even more gains on your hopped up engine.......doug
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Next question is on oil pan... I'm thinking about running a 'diamond stripper' screen style windage tray and getting one of those cheap "drag" style 7-quart pan and pickup combos - figuring the extra capacity should help keep oil temps down a little and the windage screen to keep the oil in the pan - Oil pump will probably be a melling M55HV and a matching steel sleeved shaft. anyone have a better "budget" oiling setup without going dry-sump
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#28
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Next question is on oil pan... I'm thinking about running a 'diamond stripper' screen style windage tray and getting one of those cheap "drag" style 7-quart pan and pickup combos - figuring the extra capacity should help keep oil temps down a little and the windage screen to keep the oil in the pan - Oil pump will probably be a melling M55HV and a matching steel sleeved shaft. anyone have a better "budget" oiling setup without going dry-sump
OR is this overkill and I should just run the stock pan setup?
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On my new 385ci build i'm using a Hamburger 7qt marine pan with built in windage tray and a blueprinted M55A HO pump.
#29
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I used Milodon 7qt part # Mil-30902 $169.95 and MEL-M55HV pump. We also ran a 454Mag oil powersteering cooler and amsoil 20/50 series 2000, After a hard run oil temp only 210deg.
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