Hi Steve,
I use Plastigage to check clearances, it is a sort of wax strip, round in section of a certain diameter, you lay I it on the journal with a spot of grease to hold in place, then fit the cap, do not turn, remove cap and with the guage card that comes with it, you measure how much the strip has squashed out, that gives you the clearance. Here is a web link, there are others, but I do recommended it.
http://www.carcraft.com/techfaq/116_0701_plastigage_vs_micrometer/
regards, Richard