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ARP Rocker Arm Adjusting Nuts 3/8" for .620" wide slot

ARP 300-8241


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ON SALE - $21.33 OFF
ARP Rocker Arm Adjusting Nuts 3/8" for .620" wide slot $58.66
Rocker Arm Adjusting Nuts
  • 3/8" for .620" wide slot

  • Specifications:

    For Use with Stud Girdle
    Sold as a set of 16
    Rocker Arm Nut Style
    Rocker Arm Style
    Outside Diameter
    0.62 in.
    Overall Height (in.)
    Manufacturer's Part Number:

    ARP's Perma-Loc Rocker Arm Adjusters are a true 'poly lock' that you wont have to continuously tighten. These rocker arm adjuster are heat-treated all the way through, eliminating the thread “movement” that is common to other adjusters. The threads are machined exactly perpendicular to the bottom of the adjuster, so they seat evenly and applies pressure on a full 360° circle. Set screws are machined flush on the bottom (not pointed) so they will have optimum contact on the rocker arm stud. A compact 12-point head is designed to hold your wrench in position while you lock the set screw with an Allen wrench.


    • Heat-treated premium grade A 8740 chrome moly steel
    • 190,000 psi tensile strength
    • Precision machined threads
    • Locking set screw ground flush with rocker arm stud
    • Exclusive 12-point head
    • Doesn’t require special tools

    Note: Because there are many different style rocker arms made by manufacturers, it is recommended that you verify the physical dimensions and thread requirements.


    300-8241 is rated 5.0 out of 5 by 1.
    Rated 5 out of 5 by from Easy to install , Quality part The ARP items are always a quality part. You pay for what you get, they are expensive but well worth the piece of mind knowing they will last and hold the adjustment I made to my SBC. Two tips to anyone using this type of rocker arm lock down , 1 You will need taller valve cover to clear the top of the adjuster, 2 When locking the Allen bolt use the last 1/8 turn in conjunction with the adjuster to complete lock down procedure. So if fact you will be turning the adjuster as well as the center Allen bolt. I went 1/8 turn short of my [SBC] 3/4 turn from zero lash preset and used the last 1/8 turn to lock the adjuster and Allen bolt together. I hope this helps anyone with their project in the near future.
    Date published: 2018-03-08
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    Some parts are not legal for use in California or other states with similar laws / regulations