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420A 7100 rpms

Posted by Jonnychance, May 15, 2019

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  1. Jonnychance

    Jonnychance Probationary Member

    23
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    Joined Jul 2, 2017
    Cashmere, Washington
    I barely went over the rev limiter to abt 7100-7200 is my okay it's just drives perfectly fine
     
  2. o0GuitarKid0o

    o0GuitarKid0o Proven Member

    750
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    Joined Dec 12, 2013
    Winnipeg ,MB, MB, Canada
    If its stock keep it below the rev limit but if you have aftermarket valve springs and built motor to handle more rpm than giver .

    The Thing you gott be careful with is valve float
    Research it
     

    Street Build 566  7

    1991 Plymouth Laser RS Turbo
    fwd · automatic · 1G DSM
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  3. BLACK'98DSM

    BLACK'98DSM Proven Member

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    Hoover, Alabama
    Don't worry if it drives fine but never ever do that again.
    Unless you want broken stuff
     

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  4. rabenne

    rabenne Proven Member

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    Kenosha, Wisconsin
    You hit the limiter? Or went over it?
     

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  5. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    You have 24 hours of driving left before she blows up. It's now a ticking time bomb. j/k ROFL
     

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  6. curt-s

    curt-s Proven Member

    747
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    Winterville, MB, Canada
    It is hard to answer that question because, while a new motor could do 7000rpm (provided it was capable of that), the same motor 10 years later might let go. too many variables, parts, age..
    hell even the exact same two parts new can vary -- one handles something, the other not so much.

    generally, if you have revved too high, it does not take too long to show itself. but, at the same time, perhaps the high oil pressure induced by the high rpm dislodged something which is now reducing flow to a bearing surface.. and that ticking time bomb analogy becomes more friction than fiction (teehee).

    only time will tell. keep an ear out for strange noises.
     

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  7. Canadian_CD9A

    Canadian_CD9A Proven Member

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    Winnipeg, MB, Canada
    I bounce my engine off the 7500 RPM limiter all the time in autocross, so I highly doubt any damage was done; the limit would be lower if there was a risk at that RPM. Stock valve train (with stock cams) will go 8,000 or more, but the connecting rod bolts probably aren't safe past 8,000.
     
    Mello likes this.
  8. Jonnychance

    Jonnychance Probationary Member

    23
    0
    Joined Jul 2, 2017
    Cashmere, Washington
    Okay thanks guys yeah I drive the completely stock 420a motor and it sees 5000 to 6000 rpms daily shld I install new valve components or other parts?
     
  9. ThunderChild

    ThunderChild Supporting VIP

    2,524
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    Joined Jan 5, 2012
    Rathdrum, Idaho
    My vote is keep it stock and don't thrash it too hard unless you want to rebuild/fully build sooner or have a second car.

    420a's in stock form are nice little driver's if maintained well and not wrung for everything they're worth, but past that you start noticing shortcomings relatively quick.
     

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  10. Canadian_CD9A

    Canadian_CD9A Proven Member

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    Winnipeg, MB, Canada
    Oh, 420A. Don't do reliability mods, it's cheaper to just throw a junkyard engine in if yours blows up.
     

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