Head Clearance Measuring Tools?
After working for over 20 years as a tool and die maker, I'd stay away from the calipers. They work great when you hold them perfectly square to the surface you are checking and take your reading while in that position. Not always an easy task when holding an engine or head in oyur other hand. A set of depth micrometers will provide a far more consistant and accurate measurement for a beginner using precision measuring tool. I haven't looked at the set at Sears but I think they would do a very good job.
Trying to split thousands on any dial or vernier calipers is really not giving a very good measurement because they just aren't that accurate. I have a very nice set of 0-12" digital calipers made by Mitutoyo that displays .0005 accuracy. I would use them to measure a deck height if I wanted to get closer than .002. It is rare to see a set of depth micrometers that are graduated less than .001. On depth mics I will guesstimate tenths knowing that it is only a guesstimate.
Always try to read your mics in the measuring postion. You wouldn't believe how often you can bump the spindle and change the reading when going from the measuring position to bringing them up to your face to read them. I don't recommend using locks either as you can move the spindle while engaging the the lock as well.
Most people I have trained in the shop don't believe me so I have to prove it to them. If you want accurate measurements your won't be sorry my way.
I am a hack in many respects, mostly flying, but when it comes to my work I am a perfectionist!
basmntdweller