Rob,
It's call the "Jo block" method or Gage block. (Hardly anyone calls them Johansen blocks anymore).
The procedure entails using a depth gauge base on your dial indicator, resting on a pair of identical gage blocks, which in turn rest on the edge of the cylinder.
- The indicator, base and gage blocks are placed on a flat surface like a surface plate or piece of glass
- The indicator is moved down so that there is slight preload on the tip (needle moves off zero) and then the screw holding the indicator is tightened
- The gauge scale is turned to set zero opposite the indicator position
- With the indicator zeroed, the entire stack is picked up and moved to the top of the cylinder. The gage blocks rest on the cylinder edge
- Holding the stack tightly, the crank is rotated to bring the piston to TDC.
- At TDC, the indicator point will be depressed and the indicator will read the sum of dome height and deck height. Subtract the dome height to get the deck height
Here is a photo of when I used this method to measure deck. Note that you need an indicator with a stroke greater than your anticipated dome height. A 25mm travel indicator would be fine.
