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Camshaft for 350

Old 08-17-2011, 07:51 AM
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Default Camshaft for 350

I am in the process of replacing the 350/260 engine in my scorpion 230. The engine I am replacing it with was built by a local machine shop, I was told it would have a conservative 350+ hp.(@ 5000RPM) I was just wondering on your take on it. The engine has 9:1 compression 4 bolt stock bottom, (heads) 2.02/1.60 valves with 3 angle blended bowls unshrouded valves and a 30 deg. backcut on valves, cleaned up runners, gasket matched and pinned studs. Weiend stealth air gap intake ( has roughed up runners for better fuel atomization) gasket matched with 2 inch spacer and a holley 600 spread bore carb with stub stack. The cam specs are 262/272 adv duration, 204/214 @ .050, lift 420/442 and a lobe seperation of 112. Stock omc exhaust (for now) with warmed over and smoothed runners and thru hulls. I am concerned with cam. Is it enough to get me to the 350+ hp mark and with a ls of 112 will this give me probs. with water reversion. A lot of the cams I read about are at 114. Any input would be greatly appreciated. Thanks
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Old 08-17-2011, 08:20 AM
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IMHO your cam should work pretty good as far as in a boat but as far as making 350 hp with that cam and stock exhaust manifolds I highly doubt your going to be anywhere close to that unless you have some really killer heads, I'm thinking more like 275-280, RM builder might chime in with his wisdom, Smitty
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Old 08-17-2011, 09:39 AM
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I hope I have more than a 15 hp gain over a stock 260 hp merc with 8.5:1 low rise cast intake and carb with a stock heads (76cc 1.94/1.50 single angle valve job) and a cam of 202/214 dur and 395/404 lift. I have alot of time and money into it. Thanks
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Old 08-17-2011, 11:16 AM
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Go with the lt4 hot cam from gm, it will wake it up and you can run it with stock exhaust
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Old 08-17-2011, 11:45 AM
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The camshaft you chose is less powerfull/smaller than the stock marine camshaft.
You will need at least 218/224 degrees of duration @.050 lift to get close to 350 horsepower.
The camshaft used in the 350/350 horsepower 1969 Corvette engine had 224/224 degrees of duration @ .050 lift.
For best performance install a camshaft with 110 degrees of LSA (lobe sep angle).
Dennis Moore
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Old 08-17-2011, 12:11 PM
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I won't have to worry about water reversion with that cam. I thought I had to stay around a 112 or 114 LSA to avoid this.
Again thanks for all the great info.
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Old 08-17-2011, 04:55 PM
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Originally Posted by Dennis Moore View Post
The camshaft you chose is less powerfull/smaller than the stock marine camshaft.
You will need at least 218/224 degrees of duration @.050 lift to get close to 350 horsepower.
The camshaft used in the 350/350 horsepower 1969 Corvette engine had 224/224 degrees of duration @ .050 lift.
For best performance install a camshaft with 110 degrees of LSA (lobe sep angle).
Dennis Moore
I agree, cam is REAL small and I would be surprised if it made 300 hp especially with stock manifolds. In the old days I would have bought a cam from Ultradyne for it with numbers like this (IF exhaust was going to be upgraded but stock heads were kept))
276/286 112 .454/.454 221/230 Biggest cam for stock-style spring. Excellent in 350-400 size engines. Largest cam with power brakes. 1500-6000
I really liked that grind and ran it in motors with mild compression with good luck, that cam with 882 heads ran away from my zz4 350/350 hp crate engine in the same vehicle
Today however I would just call RMBUILDER and buy what he reccomends as he optimizes these set-ups. If your motors already done and ready to go in though I would say just run it and enjoy your boat, it just won't make quite ass much as you were hoping for, Smitty
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Old 08-17-2011, 10:04 PM
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Thanks for all the info. How do I get a hold of RMBUILDER
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Old 08-17-2011, 10:26 PM
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Comp Cams makes a small block (and BBC) "Maximum Marine Camshaft".....it is the maximum camshaft reccomended for marine use, Im assuming without risking reversion....you may want to check it out.
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Old 08-18-2011, 12:03 AM
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Originally Posted by pipes View Post
Thanks for all the info. How do I get a hold of RMBUILDER
He's actually in Rochester, 585-654-8583
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