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Home›Repair guides›Hercules›Installing And Timing Roosa DM Pump

Hercules G4800 — Installing And Timing Roosa DM Pump

Adjustments · Fuel injection pump

For the Hercules G4800, from the Hercules service manual.

Procedure

  1. Spot vibration damper at proper degree mark before TDC No. 1 compression.
  2. Install new O-ring seal on pump attaching flange.
  3. Remove timing hole cover; rotate pump until timing marks register.
  4. Install pump to drive gear, aligning keyway.
  5. Install lockwasher and nuts on attaching studs.
  6. Install flat washer and nut on pump shaft; torque to 150 ft lbs.
  7. Recheck timing.
  8. Install drive gear cover plate and timing hole cover.

Tools required

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Torque pump shaft nut to 150 ft lbs
  • Timing setting 20 deg B.T.D.C.

Source: Hercules service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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