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Thread: Possible bent valves

  1. #1
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    Vl

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    Default Possible bent valves

    Hey guys
    I just finishing putting a head on a vl from a diff block and I think I was a tooth out on the timing when I first started it. I quickly corrected it but the car is missing. I did the old paper on exhaust trick and it sucks in the paper before it blows it out. Also the exhaust manifold has large amount of steam or smoke coming from it and it almost smells like burning oil after about a minute okf running. Also note, I was on tdc and I had the cam timing mark properly set before I started.
    I'm not a dullard, I'm actually a mechanic by trade so I was sure I did everything proper, I was rushing it so that's why I properly didn't count the teeth properly.
    I'm going to to a compression test tomorrow to see if it is bent valves but I just wanted some opinions first.
    Those are all the symptoms I can think off, also the car hasn't run for about 8 months but I've ruled that out as I've thoroughly cleaned most parts for carbon build up.
    What do you guys think?

  2. #2
    detox_nath83's Avatar
    detox_nath83 is offline Another VL Driver
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    Firstly the rb30 is a free spinner meaning if u snap the timing belt or whatever the pistons can't hit the valves to damage them. I would think warped head or wrong torque sequence or setting. Did u get the head machined b4 u put it on?New head gasket?

    Also a valve might not be seated correctly causing your suck in the exhaust from deposits

  3. #3
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    the head didn't need machineing and wasn't warped.
    its not the valves, its something else. I've five the process of elimination with so many thing but I can't get it. the only problem is its missfiring off its tits. the funny thing is it want missfiring as much till after I did a decomp test. yes, I double checked the leads and spark plugs. I think this is beyond me and needs a tune.
    unless anyone has any other theories.

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    If a head has been on another engine as soon as u undo the head it will warp ever so slightly. All heads should b machined before installing on an engine.. U would know this being a mechanic.

    Misfiring.. Could b crank angle sensor failing as this controls spark pattern

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    its has a new CAS, cap and rotor button. now coil too. AFM is fine before you ask. new leads and plugs. new fuel pumps + filter.
    i used a straight edge to see if the head had warped when it was removed. it was as straight as a boner.
    ive taken all the correct steps along the way, but clearly ive missed something.

  6. #6
    PaRaDoX's Avatar
    PaRaDoX is offline Not a chev.....
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    Quote Originally Posted by Vl_lover View Post
    its has a new CAS, cap and rotor button. now coil too. AFM is fine before you ask. new leads and plugs. new fuel pumps + filter.
    i used a straight edge to see if the head had warped when it was removed. it was as straight as a boner.
    ive taken all the correct steps along the way, but clearly ive missed something.
    1 tooth is not enough to bend a valve aswell (plently of RB30's slip a tooth from time to time), I believe the term you're looking for is non-interferance. How to tell the difference is the non-interferance engines usually have recesses in the pistons for the valves.

    First things first. Do a compression test as this will show any valve issues if its a N/A VL it should be round 8.4-8.5:1 which should give a result of around 150psi. As someone else said you may have a warped head or a faulty headgasket.

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  8. #8
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    i am a mechanice. i only asked if it was valves because i could be ####ed taking the head apart again, but BECAUSE i am a mechanic i managed to solve the issue, i forgot one thing. the O rings on my after market injectors. they were letting air seep in to the channel where the injectors fire causing it to run very rough.
    Bare in mind i took this car apart 8 months ago and i seem to have forgot to put the injector O rings back on when i had them cleaned.

    All is good now thanks anyway

  9. #9
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    thanks paradox, a comp test is the first thing i did, they were all 150+-. My bottom end is non interfearnace, i know that much because it has after market pistons which are flat surface, not dished or raised like the N/A or turbo pistons.
    thanks though

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