Cylinder Head Overhaul

Cylinder Head Overhaul

Valve Spring Compressor:

1. Using the valve spring compressor 18G106A or a suitable alternative, remove the valves, springs and umbrella seals, retain them in sequence for refitting. Discard the umbrella seals fitted to the inlet valves only.

Cleaning Combustion Chambers & Valves:

2. Clean the combustion chambers with a soft wire brush.
3. Clean the valves.
4. Clean the valve guide bores.
5. Regrind or fit new valves as necessary.

Valve Faces:

6. If a valve must be ground to a knife-edge to obtain a true seat, fit a new valve.
7. The correct angle for the valve seating face is 45° ±1/4.
8. The correct angle for the seat is 46° ±1/4 degrees and the seat witness should be towards the outer edge.
9. Check the valve guides and fit replacements as necessary. Valve Guide

10. Check the valve seats and fit replacements as necessary. Valve Seat

Re-Assemble valves to cylinder head

Valve Spring & Components:

1. Before fitting the valves and springs, the height of each valve above the head must be checked. Insert each valve in turn, in its guide and while holding the head firmly against the seat, measure the height of the stem above the valve spring seat surface. This dimension must not exceed 47.63 mm (1.875 in). if necessary fit a new valve or grind the end of the valve stem.
2. Lubricate the valve stems and assemble the valves, fit new umbrella seals and springs, fit the caps, compress the springs and caps using spring compressor 18G106A and secure the springs in place with the collets. Note that the umbrella seals are only fitted to the inlet valves.