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Rockwell hardness of valve lifters

  1. Jul 23, 2010 #1
    Hey guys, I have a set of rocker arms that I converted from a hydraulic to a mechanical adjuster and I am having problems with the adjuster screw im currently using. Whats happening is that when the adjuster screw hits the valve lifter, its digging away at the top of the lifter causing a minor pit to form. The adjuster screw tip also has had some material that has been grinded away.

    I cant find any other adjusting screws in that size except for some steel set screws from mcmaster-carr. I purchased them and will get the ends machined to a round point with hopes to use them. I believe the oem hydraulic rocker arm has a hardened steel tip where it contacts the valve lifter.

    So I was wondering if the machined set screws will prevent more damage to the end of the valve lifter or would I have to harden the set screws?

    The set screws have a rockwell hardness of C45 according to mcmaster-carr. I have no idea what type of material the oem rocker arm is made out of.

    Also, why would both the valve lifter and adjusting screw have damage? Shouldnt it only be one or the other if the hardness was different?

    Thanks in advance for any help guys. Let me know if you guys are confused about anything, ill try to clear it up.
  2. jcsd
  3. Jul 24, 2010 #2

    Ranger Mike

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    been there done that
    you can not use hydraulic cam valve train components on a solid mechanical camshaft. the cam ramp is different as are the components..the hydraulic cam components are designed to work with the presence of motor oil in the lifter and this whole valve train runs a lot less harsher then the solid lifter set up which is straight metal to metal..hence the hydraulic set up is quieter smoother has less vibration...the solid bumstick set up is solid metal all the way thru and is hardened to take the abuse. if you swap out pieces and mix and match parts it will run ..for a little while...then you wipe out a lobe or lifter or maybe even a set of main bearings...do not do it!
  4. Jul 24, 2010 #3
    I understand that it will be more harsh and make more noise but there are a few companies out there that have converted hydraulic rockers to a mechanical design with success so it can be done. They use adjusting screws out of pre existing engines. I took out an adjusting screw out of a honda civic and the tip feels and looks exactly like the tip of my stock hydraulic rocker.

    I could have just bought one of their kits but i am a diy kind of person so I decided to design my own.

    I guess my actual question is, what kind of material is the tip of the stock rocker arm? Is it simply hardened steel? Can i harden the set screws i bought to the same hardness by heating it up and dipping it in oil?
    Last edited: Jul 24, 2010
  5. Jul 25, 2010 #4

    Ranger Mike

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    i think you will find that the manufacturer has already hardened the screws...just about all valve train parts are hardened simply to avoid warranty costs..
  6. Jul 25, 2010 #5


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    I probably wouldn't bother with this. The manufacturer has spent thousands of hours of engine testing alone trying to minimise valvetrain wear. Wear isn't about making everything hard, and it's not always (or even usually) the softer component that wears more rapidly. You could try hardening your new machine screws only to find that you start getting Hertzian cracking or some such under high load conditions.

    Try it by all means but be prepared for some unsavoury lessons learnt.
  7. Jul 27, 2010 #6
    For knowledge by going to the new job.
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