370 high mid to WOT engine rattle
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  1. #1
    Junior Member SANDMANIAC's Avatar
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    370 high mid to WOT engine rattle

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    half a minute ago · #1
    370 high mid to WOT rattle...
    Put together a fresh 370 about a year ago...when it hits the upper mid to WOT there's a rattle that occurs...after several times out, it was taken apart and no sign of piston slap at all...then because of needle clip position issue at Pismo the top-end was bored and new slug was installed with the correct clearances and carb adjustments and again, the same rattle...I swear it sounds like piston slap, but no signs of that at all...all bearings are new, new crank and everything else concerned, no sign of piston to dome contact...timing is at +5 with 110 race fuel, large radiators, Klotz Super Techniplate at 36-1...BDT intake and BDT Werks Expansion Chamber...Has anyone experienced anything like this and/or does anyone have any suggestions??

  2. #2
    Senior Member 2ndmoto's Avatar
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    Sounds like you checked the top end out pretty well. Are you sure it's coming from the top end? Maybe cb, clutch or rotor? Not sure if it's a power valve motor, but I have had some cr pv motors make a little bit of noise.

    Could it be detonating? Sounds like you burned it down because of a needle. Maybe it's right on the edge. Try fattening it up and running it back at stock timing.

    Best regards
    -Jason

  3. #3
    Senior Member matuus's Avatar
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    run my 363 stock timing. no advance.


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  5. #4
    Junior Member SANDMANIAC's Avatar
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    Quote Originally Posted by 2ndmoto View Post
    Sounds like you checked the top end out pretty well. Are you sure it's coming from the top end? Maybe cb, clutch or rotor? Not sure if it's a power valve motor, but I have had some cr pv motors make a little bit of noise.

    Could it be detonating? Sounds like you burned it down because of a needle. Maybe it's right on the edge. Try fattening it up and running it back at stock timing.

    Best regards
    -Jason
    Thanks for the response Jason...it's not "pinging" as detonation would normally do...no powervalve...and about a year ago, due to a to a center clip it did "begin" to melt, but I stopped it in time...this time all variables were taken into consideration and same knocking as when the original motor was ran without issues in the High Desert...I'm at a loss...seriously...lol


 

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