383 question

Discussion in 'Gas Engines' started by gets, Feb 16, 2011.

  1. gets
    Joined: Feb 2011
    Posts: 2
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    Location: North Shore

    gets New Member

    I am a new member to the forum but have been reading the threads researching for my re power. First off I would like to thank everyone for the great information that I've seen here.

    Ok here goes. I am currently restoring/repairing a 30' skeg built lobsterboat (semi-displacement). The boat currently has a sbc 350 with closed cooling(keel cooler) and dry exhaust, not sure of the year. I also have a Sea Ray which I am parting out that has a merc 260 (sbc) that was new in '99 I think with raw water cooling and less than 400 hrs on it. After much thought on how I want to power the boat I have settled on a 383 stroker for the added hp and torque and the fact I should be able to use parts off the other engines. I want to get an approximately 15kt cruise from the boat which shouldn't be a problem with this hull type.

    If I could get this engine:
    383 stroker has 2.02 int. 1.6 exh. valves cast iron heads roller rockers, 10.5-1 compression (pump gas friendly) dynoed @ 436 hp with edlebrock performer and 750 cfm. vac secondary carb have some billet pulleys and brackets,billet valve covers(yes there are 2), Milodon 7qt. oil pan, new harmonic balancer, a used EDLEBROCK open plenum intake. motor has 0 mi.on it the only run time on it was the dyno was a friend of mines motor built for a CAMARO project that never happened. Crank is forged steel Scat #435050, forged steel rods 5.7" have 3/8 cap bolts, Pistons are SPEEDPRO hypereutectic with coated skirts, the cam is COMPCAMS #12-246-3, the roller rockers appear to be PROFORM with 7/16 screw in studs, COMPCAMS hydraulic lifters, springs, rods and guide plates, dual row timing chain, harmonic balancer is a new pro/street and have the plate counterweight for balancing that goes behind the flywheel or flexplate ) unfornatly the previous owner lost most of the paperwork for what he bought but your more than welcome to come check it out the valve covers and oil pan are on loosly for inspection

    for 2k or less would I be better off than rebuilding one of my other blocks. I realize I would have to change some things for better marine performance but don't know if I just put a different cam in or if that will just start a domino effect which will cause me to wind up spending as much as rebuilding one of the other blocks. I think I would want to get that comp ratio down some.

    Any input is greatly appreciated.
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The camshaft is the first thing to look into. On a car, the engine may be set up for max HP at high RPM. This may be OK with a high stall torque converter, but will suck for a boat. It may take forever to plane or simply won't ever get the RPMs high enough to produce the HP. The harmonic balancer may also be a problem unless you find how to match it to the application. I am not familiar with the model, but you may be able to get the info from the manufacturer. The oil pan and pump pickup may not work unless it is setup for a tilted motor as in a boat. On cars it tends to be more horizontal. Also, some deep pans will touch the bottom of the boat. You need to measure that. When you say you want 15kt cruising, does that mean at about 80% power?
     
  3. gets
    Joined: Feb 2011
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    Location: North Shore

    gets New Member

    Somewhere in that general range. I will install a floscan and use that to really know where my optimal cruise is. My main concern with purchasing the 383 is can I just use a new cam to get everything where I want it or will I have to change a lot more. I have some sbc books on the way but I am loving learning about this stuff. And I should probably jump on that motor if it's worth it.
     
  4. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Open plenum intakes do great at high RPM but have less low RPM torque. It is not ideal for hole shot on a boat. If you want high performance, you should look at a complete package. Mixing components without a complete plan is not efficient. In other words, you should design the engine, map a HP and torque curves and then specify the components that will give you that.
     

  5. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    I want to get an approximately 15kt cruise from the boat which shouldn't be a problem with this hull type.

    This might be 15 -20 GPH of fuel burn.

    FF
     
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