Originally Posted by tabetha

The most sure fire quickest way is after taking the plugs out to change or clean them during service just put car in 4th and move till 1 tappet of each cylinder in turn is pressed down then adjust the other one in that cylinder.
The endura is indeed a refined version of valencia, when adjusting the rockers pull up on the rocker with your fingers at the same time as inserting the feeler gauge, these suffer terribly with wear, this way you get a true gap.
If the rocker shaft is badly worn it can be taken out spun 180 degrees and reinstalled upside down so unworn side is on bottom instead of worn side of shaft.
tabetha