How to Change Rocker Box Gaskets on the Harley Evolution

Written by don davis
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How to Change Rocker Box Gaskets on the Harley Evolution
This Harley has a Blockhead engine. (I will be back shortly image by A. Leonardo from

The Evolution engine was a significant upgrade over the preceding Shovelhead power plants. Part of the redesign was the replacement of the spade-shaped Shovelhead rocker covers with rocker covers that looked like a stack of blocks. Harley cheerfully nicknamed its new engine the Blockhead. Unfortunately, the Blockhead's rocker covers leaked. The covers were redesigned four times. The earliest rocker box gaskets, and the worst, were made of cork -- they were nicknamed "glue and screws." Later generations of these gaskets were made of rubber. Although you can replace these gaskets without pulling off the gas tank, experienced mechanics usually do so.

Skill level:

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Things you need

  • Allen wrenches
  • Screwdrivers
  • Gas storage can
  • Box wrenches
  • Socket wrenches
  • Gasket scraper
  • Gasket adhesive
  • Service manual
  • Torque wrench

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  1. 1

    Park your Harley in a well-ventilated area. Turn the petcock to off. Allow the engine to cool down completely.

  2. 2

    Loosen the fender tab bolt on the back of the seat with an Allen wrench. Remove the bolt and washer. Pull the back of the seat up and back to remove it.

  3. 3

    Disconnect the negative battery cable from its terminal with a box wrench.

  4. 4

    Remove the console bracket bolt or bolts. Use a box wrench on consoles attached to the bracket with a single acorn bolt. Use an Allen wrench on consoles attached to the bracket with two or three Allen bolts.

  5. 5

    Loosen the worm clamp that connects the fuel line to the petcock with a flathead screwdriver. Remove the fuel line from the petcock.

  6. 6

    Drain your fuel tank through your petcock into a large gasoline storage can. If you have a split gas tank, you must also disconnect the crossover hose and the fuel venting hoses on the bottom of the tanks.

  7. 7

    Remove the front and rear mounting bolts, washers and nuts, using a box wrench on the nuts and a socket wrench on the bolt heads.

  8. 8

    Unplug the fuel gauge connector under the gas tank on later Evolution models.

  9. 9

    Lift the tank straight up and off the motorcycle and set it aside.

  10. 10

    Remove the Allen bolts that fasten the rocker cover to the engine. Remove the cover. Work on one rocker cover at a time, beginning with the front cover.

  11. 11

    Remove the metal gasket, which is called an inner rocker cover or a D-ring. Remove the old gasket. Some gaskets will need to be scraped off.

  12. 12

    Examine the used gasket and rocker housing. Gaskets for housings with only a partial shelf gasket use adhesive. Housings with a shelf to fully support the gasket do not need adhesive.

  13. 13

    Position the gasket on the rocker arm assembly using adhesive if needed. Replace the thin metal inner rocker cover and the rocker cover.

  14. 14

    Replace and tighten the rocker cover bolts according to the specifications in the shop manual for your Evolution. Generally, these bolts are tightened to about 10 foot-pounds of torque.

  15. 15

    Replace the gas tank and reattach the pigtail connection for the fuel gauge. Reconnect the fuel line to the petcock using a worm clamp and flathead screwdriver.

  16. 16

    Reattach the console to the console bracket. Refill the gas tank. Reconnect the battery cable and replace the seat.

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