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  1. #1
    tom
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    Do I have bent valves?

    I'm trying to figure out whether I have bent valves on my 3.5L m30b35 US spec head. I had the head resurfaced minus 0.75mm (a little more than allowable) to bump up compression and run it with a Euro Motronic. I checked to see that the valves don't interfere initially when I rotated the engine by hand, but a leak down test now shows that my compression was quite low. The engine runs ok, but its lean and hesitates at low RPM. Also slightly loud valve train when cold.

    To check the valves, I pulled the intake manifold off again and poured gasoline into the intake valves side. It held, so I know the intake valves are not bent. Does anyone know whether the exhaust valves stick down into the combustion chambers further than the intake valves when fully open? Seems like the intake valves are wider and since they are angled, the wider valve would protrude further than the smaller diameter valve, given the same amount of opening. Does anyone know which valves would hit the pistons first in case of interference?

    Thanks, Tom


  2. #2
    Big Dog
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    Re: Do I have bent valves?

    did you also install a variable cam timing gear? Decking the head changes the cam timing and will affect the overall performance of the engine. Also make sure it's not one tooth off.

  3. #3
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    Re: Do I have bent valves?

    B35 has variable timing?
    AIM: yaofeng4249
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  4. #4
    tom
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    Re: Do I have bent valves?

    No. I didn't have to do anything. I figure I compensated for the milling by setting up the cam timing by one tooth off, so it's a s it should be now. At TDC cams are pointing straight up. I guess I got lucky that o.75 mm happens to cause about one tooth slack in the timing chain....

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