Using a stretch guage - advice needed

[2cams70]

Hi Guys,
As this is my first serious engine build I decided to splash out on an ARP stretch guage. Reading the included instructions they say "You always use .200" - .400" preload on the guage and tighten the set screw and lock nut on the adjusting screw". Surely this is an error, 0.200 to 0.400" seems like a heck of a lot of preload. Should it be 0.020" - 0.040" or maybe 0.002" - 0.004"?

Any other things I need to know to get an accurate result with this gadget? - I'm using the ARP lube of course.

[nmauduit]

I don't want to crash into opened doors as we says here (i.e. what I'm about to say may be obvious to you), but my guess is preload would mean you don't want to be using the gauge towards the end of its scale, since the tip is spring loaded it always rest at the end of travel : you want to make sure that the tip will be within the proper scale portion for the whole measurement.

[rgh0]

Yes I normally set the gauge to be around mid range in its travel before I start tightening the bolts.

cheers
Rohan