Camshaft Question
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Camshaft Question

  1. #1
    Old Timer LeE ss13's Avatar
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    Default Camshaft Question

    APBA created a new Flatbottom Circle Boat class to accommodate non-capsule boats. It is called Super Comp. You have two motor choices. Option I is a $7,500 LS3 CT525 Circle Track crate motor. Option II, take your Super Stock 427 BBC and use a 650 Holley 0-80541-1 and a cam with no more that .550 lift and a duration of 230 @ .050 or less. Is there any advantage to changing the lobe centers? 112, 114? Also, is 110 octane fuel going to be good enough with 12 1/2+ compression? Is moving the cam timing any help? Total ignition timing change? Wadayathink?
    Last edited by LeE ss13; 11-05-2017 at 02:28 PM.
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    Quote Originally Posted by LeE ss13 View Post
    APBA created a new Flatbottom Circle Boat class to accommodate non-capsule boats. It is called Super Comp. You have two motor choices. Option I is a $7,500 LS3 CT525 Circle Track crate motor. Option II, take your Super Stock 427 BBC and use a 650 Holley 0-80541-1 and a cam with no more that .550 lift and a duration of 230 @ .050 or less. Is there any advantage to changing the lobe centers? 112, 114? Also, is 110 octane fuel going to be good enough with 12 1/2+ compression? Is moving the cam timing any help? Total ignition timing change? Wadayathink?
    With the tiny carb and short duration cam, maybe it just makes sense to use the crate engine, but can't say that without seeing specs on that engine. I don't think you gain power on that short cam by opening lobe centers, I think most circle track stuff will be tighter than that. I think the 110 octane is fine for that compression range.
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    Old Timer LeE ss13's Avatar
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    LS3 Specs

    Part Number: 19331563

    Engine Type: LS-Series Gen-IV Small-Block V-8

    Displacement (cu. in.): 376 (6.2L)

    Bore x Stroke (in.): 4.065 x 3.62 (103.25 x 92mm)

    Block (P/N 12623967): Cast-aluminum with six-bolt, cross-bolted main caps

    Crankshaft (P/N 12597569): Nodular iron

    Connecting Rods (P/N 12607475): Powdered metal

    Pistons (P/N 19207287): Hypereutectic aluminum

    Camshaft Type (P/N 88958770): Hydraulic roller

    Valve Lift (in.): .525 intake / .525 exhaust

    Camshaft Duration (@.050 in.): 226° intake / 236° exhaust

    Cylinder Heads (P/N 12629063): LS3 rectangle port; aluminum “as-cast” with 68-cc chambers

    Valve Size (in.): 2.165 intake / 1.590 exhaust

    Compression Ratio: 10.7:1

    Rocker Arms (P/N 12569167 int): Investment-cast, roller trunnion

    Rocker Arms (P/N 10214664 exh): Investment-cast, roller trunnion

    Rocker Arm Ratio: 1.7:1

    Recommended Fuel: 92 octane

    Maximum Recommended rpm: 6700

    Reluctor Wheel: 58X

    Balanced: Internal
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    Hmm,, iron crank, powdered metal rods, hypereutectic pistons,, $7500
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    Old Timer LeE ss13's Avatar
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    Circle Track engine builders said that when Nascar shoved the LS motor onto their classes, the LS motors got to use an 830 cfm carb to their 390s. The LS guys tried to spin them 7500 plus and found them kicking out connecting rods. In the APBA version, they will be able to use a 750 cfm carb.
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    Quote Originally Posted by LeE ss13 View Post
    APBA created a new Flatbottom Circle Boat class to accommodate non-capsule boats. It is called Super Comp. You have two motor choices. Option I is a $7,500 LS3 CT525 Circle Track crate motor. Option II, take your Super Stock 427 BBC and use a 650 Holley 0-80541-1 and a cam with no more that .550 lift and a duration of 230 @ .050 or less. Is there any advantage to changing the lobe centers? 112, 114? Also, is 110 octane fuel going to be good enough with 12 1/2+ compression? Is moving the cam timing any help? Total ignition timing change? Wadayathink?

    A lot can be done with the BBC combination based on the rules.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW
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