I bought my Sunnen dial bore gage (.0001") in 1977 for I believe $700. (About the same price as a Hemi convertible.) It seemed like a lot of money but it's the best. It's easy to use and you will really know your clearances. Today they are only $1,000. A few decades later I saved up enough to buy the Sunnen setting fixture. ($2,000.) You will start wanting one of those the day you get your dial bore gage. Don't be afraid to spend a lot of money on the best tools. They last a lifetime. 1977 was over 40 years ago.