Dial Bore Guage

[shaun]

I've bought the Tavia dial bore guage from summit a while back, http://store.summitracing.com/partdetail.asp?autofilter=1&part=TAV%2D09250&N=700+%2D111741+115&autoview=sku
I've read 1 sheet directions but i want to make sure i'm using this thing right and see if anybody has any advice/tricks/tips. One thing i noticed today when using my dial bore guage was that i got a diffrent reading if i applyed pressure on the side that didnt compress to the bearing. I'm not applying a ton of preasure but i am putting enough to keep it pressed up tight. I got diffrent readings than i did when i just held the shaft and let it float. So.. whats the proper way to take measurements with this guage?
Right now, i mic the journal, zero the dial bore guage out in the mic, and then measure the bearing in the rod/main that has been torqued.
http://static.summitracing.com/global/images/prod/large/sum-900041_w.jpg

[Moneypitt]

What you are experiencing is calibration and use differences. When setting in the mic, (calabrating) you are not exerting pressure, so the measurment should be done the same way. It is somewhat of a "feel", kinda like setting valve lash, you have to get the "feel" for it......and make it repeat a couple of times...........MP