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Cast or 4340 408 stroker crank

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Hi new guy here , am building a 408 stroked clevo and tossing up between a cast or 4340 crank. I have chi 208 3v heads and single plane manifold,  will put a hyd roller 240@.50 .612 lift and a 850 DP . Will go into a xy sedan with a toploader. Will only be a weekend streeter . Is 4340 warrented or would the cast be safice

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Hi new guy here , am building a 408 stroked clevo and tossing up between a cast or 4340 crank. I have chi 208 3v heads and single plane manifold,  will put a hyd roller 240@.50 .612 lift and a 850 DP . Will go into a xy sedan with a toploader. Will only be a weekend streeter . Is 4340 warrented or would the cast be safice


Cast cranks are much tougher than people will give them credit for. A stock Clevo 4MA will spin to 7500 no probs if everything's balanced and prepped right. If you can get hold of a neutral balance one, even better. If it's just a weekend cruiser, that might not even be an issue.

Being a stroker, it will be all about the mid-range torque, not the top end, so even less reason to go steel.

Steel cranks are really only for serious, sustained rpm. Total overkill for what you're building.

Sent from my CPH1607 using Tapatalk

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With 408 & 240 @.050'' cam, peak HP would be around the 6000-6200ish rpm mark so fine for cast crank,

I would upgrade to 4340 if regularly reving over 6800rpm,

 

Tho wounding if CHI dual plane, airgap type manifold would be more suited for RPM range of engine,

would make more low & mid range torque with dual plane over single plane.

 

I could feel the difference when I changed from hi rise single plane to dual plane, picked up heap more low to mid torque (but was a 302🤔lol)

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Your right about their dual plane , maybe down the track.  Have modeled this build off the nulon xy engine,  it uses a single plane. That's why I went that way. Have read the cast cranks take a bit to balance,  have you had any experience with them? Cheers 

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Balanced is balanced, no matter what material it's made of.....  Some companies grind material off the webs, some drill holes, (and/or fill with weights.)

Just make sure you balance the WHOLE rotating assembly together. Flywheel/flexplate + crank + rods +pistons + harmonic balancer etc, etc.

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All depends on the rev range you want.  As others have said, 5,500 -6,000 rpm is fine on a balanced stock crank. Clevo's weak points are the oiling system, the 5/16 rocker studs, and standard valves will pop their heads off at 6 grand. Strokers are torque makers, and the lower the rev range the longer everything will last.

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