Perkins — How to adjust the bridge piece and set valve clearance
Adjustments · Valve train
From a Perkins owner's manual covering: 4000 Series, 4006-23 TAG1A, 4006-23 TAG2A, 4006-23 TAG3A. Check it applies to your exact model before use.
Applies to: Perkins 4006-23 TAG1A, Perkins 4006-23 TAG2A, Perkins 4006-23 TAG3A
Before you start
- Disconnect the batteries and any other power that can start the engine.
- The bridge piece must be adjusted before the valve adjustment is made.
- Check that there is a clearance between the bridge piece and the inlet and exhaust rockers.
- When contact is made with the valve, the valve must not move.
Procedure
- Remove the setscrews (A1); remove the rocker cover (A2) and discard the cover joint (A3).
- Rotate the engine to the required position, given in table 2.
- Check that there is clearance on both valves.
- Loosen the lock nuts on each of the bridge pieces (C2).
- Turn the adjuster (C3) out until the fixed side of the bridge piece rests on its valve.
- Hold the top edge of the bridge piece (C1) and turn the adjuster screw (C3) down until it contacts the valve.
- Tighten the lock nut (C2) to 50 Nm (35 lbf ft) 5,1 kgf m without moving the adjuster screw.
- To set valve clearance, loosen the lock nut (D1), put the feeler gauge (D2) between rocker and bridge piece, turn adjuster (D3) to make a slide fit.
- Tighten the lock nut (D1) to 50 Nm (35 lbf ft) 5 kgf m without moving the adjuster screw (D3).
- Check that the valve clearance is correct; fit a new rocker cover joint (E3) and the rocker cover (E2).
- Fit the setscrews (E1) and torque to 4 Nm (2.9 lbf ft) 0,4 kgf m.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Bridge piece lock nut 50 Nm (35 lbf ft) 5,1 kgf m
- Valve clearance lock nut 50 Nm (35 lbf ft) 5 kgf m
- Rocker cover setscrews 4 Nm (2.9 lbf ft) 0,4 kgf m
- Valve clearance 0,4 mm (0.016 in)
Source: Perkins owner's 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.