Refit the rocker box and pull it down to the head evenly by means of the fixing bolts. See that the push rods engage properly in the sockets in the bottom rockers and are in their correct respective places (exhaust in exhaust rocker and inlet in inlet rocker).
The utmost cleanliness is essential when carrying out this operation and the faces of the rocker box and valve covers must be perfectly clear of all the old jointing compound. Smear the faces of the rocker covers and the outside of the spring covers with jointing compound before refitting. There are numerous brands of jointing compound available, but goldsize is a good substitute. Having tightened down the rocker box and covers tighten up the nuts on the top flange of the push rod cover, and tighten gland nut.