Trial fit of a plate for the magnetic base of the dial-gauge, secured to the exposed threads of the two end cylinder-head studs. The plug leads have been moved out of the way, the plugs themselves will also be removed to make turning the engine easier.
Positioned with the dial-gauge plunger resting on the valve-end of a rocker.
The measurements will be taken with the rocker fully up, so the fact the top of that end of the rocker isn't flat and smooth makes no difference, as the dial-gauge won't be moved between measurements.
The strict rule-of-nine point. The actual reading is immaterial, it is how it varies as the cam is rotated round the back of the lobe that is important.
A few degrees one side of the strict rule-of-nine point, and 0.035mm or 1.4 thou greater clearance.
Out of interest a comparison with the valve end of the rocker pushed fully down to indicate the clearance: 0.4mm or 15.7 thou.
The full sequence and a guide as to when when individual valves can be adjusted with my cam:
| Cylinder 1 | Check | Cylinder 3 | Check | Cylinder 4 | Check | Cylinder 2 | Check | ||||
| Intake | 2 opens | Exhaust | 5 opens | 4,6 | Expansion | Compression | |||||
| 2 closes | 5 closes | ||||||||||
| Compression | Intake | 6 opens | Exhaust | 8 opens | 7,1 | Expansion | |||||
| 6 closes | 8 closes | ||||||||||
| Expansion | Compression | Intake | 7 opens | Exhaust | 4 opens | 3, 5 | |||||
| 7 closes | 4 closes | ||||||||||
| Exhaust | 1 opens | 8, 2 | Expansion | Compression | Intake | 3 opens | |||||
| 1 closes | 3 closes |
Detailed position of the reference valves, in the order they appear as the engine is rotated so only two full turns of the engine are needed:
| Order | |
| 1 | 8 halfway down |
| 7 | 8 just fully down |
| 3 | 4 fully down |
| 5 | 4 fully down |
| 8 | 1 just starting to go down |
| 2 | 1 fully down |
| 4 | 5 halfway down |
| 6 | 5 fully down |
Note that valve 5 i.e. cylinder 3 exhaust is the only one that conforms to the strict Rule of Nine system i.e. its nine's-complement 4 (cylinder 2 exhaust) being fully down, some others being close but the rest way out.
The engine is rotated by putting the gearbox in 4th, handbrake off, then using the off-side front wheel to nudge the engine round while looking at the valves. This moves the car forwards bit by bit so if you run out of available space take it out of gear, roll the car back, put it back into gear and carry on. I can do all mine in two goes of about 3 ft each.