Valve Lash

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Nitro Diver, Apr 5, 2017.

  1. Nitro Diver

    Nitro Diver Member

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    I have come across this on a few different engines (Hemi's) with different cam / lifter / rocker setups where the lash on number 6 intake when set at TDC becomes loose around 30 degrees ATDC like the timing on that lobe is retarded for some reason, has anyone else come across this or know the reason for it?
     
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  2. kosky racing

    kosky racing Comp Eliminator

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    Sounds like a wrong cam in right block - raised cam blocks take a 48* standard cam height 45*
     
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  3. Nitro Diver

    Nitro Diver Member

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    Definatly 48* cams, it was the first thing I checked. Its only on number 6 cylinder not the whole bank
     
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  4. Mike Kern

    Mike Kern New Member

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    How loose are we talking here? .005" or .040"? What's the number? Possibly a loose cam/bearing clearance and the cam is being flexed by spring pressure from another cylinder. Think about the spring pressures we run now.
     
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  5. Nitro Madness

    Nitro Madness Super Comp

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    I have had cams that the valve lash measured slightly different depending on where on the base circle you positioned the cam....and always suspected the base circle was not concentric with the center of the cam...hoping one of the cam gurus could chime in here and give us a little more technical answer....but if you have the cam out of the engine - maybe check it up in a lathe and check the base circle on each lode with a dial indicator...or find someone with a Cam Doctor to check each lobe...
    Let us know how this turns out....curious minds wanna know...
     
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  6. blwnaway

    blwnaway Member

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    For years I marked my balancer every 90* to set valves quickly via firing order and got away with it. Now every valve is about .02 off doing it this way and #7 is .03-.04 off.
     
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    Last edited: Apr 6, 2017
  7. Mike Kern

    Mike Kern New Member

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    Intake closing, set/check exhaust...Exhaust opening, set/check intake
     
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  8. talbot35

    talbot35 Member

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    I believe mine does that too
    Right Micky.
     
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  9. jay70cuda

    jay70cuda Member

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    I've had 2 cams doctored and you can't believe how far off they are. Not gonna mention names cuz it's not fair however I've seen the middle cylinder be off up to 6 degrees . Lift and closing points that make no sense. It's lazy machining is all it amounts to. Ask your self when you need a cam in 2 days and they haven't made it yet, how can it get there so fast and be dead nuts?? Cnc, yes but grinding excessevly and heat makes for sloppy cams. And yes it's robbing you of horsepower.
     
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