1. Head should be removed to do properly .. and supported level.

2. http://www.beecroft-science.co.uk/20...roductList=328
Dont think you will buy a lot cheaper. Last one I used was a 200Ml, but was plenty big enough, reckon a 100 would be OK.

3. Stuff I do ...
Grease the bores a little to seal ring gaps, etc.
Perspex plate greased onto the head surface (to seal off) with a small filling
hole in the centre.
Make sure valves aren't leaking (or seal/wipe off with grease)
Use Paraffin to measure up, not water. You want something like this with low
surface tension!