On my race engines, I don't trust Plastigauge. I torque up the rod and main bearings with the crankshaft removed, and measure the actual inside diameter, down into the .0001" range, then measure the crank journal and subtract the difference to get the clearance. Then I polish each crank journal individually to get an exact clearance on all the bearings.
Jerry
I have no doubt YOU possess the skills to use measuring tools correctly but in supervising a bunch of machinists who constantly swear thier tools are used and calibrated properly CMM inspection continually proves otherwise. For the average person plastigauge eliminates human error and is readily available to anyone at low cost.
I agree. If you're checking with an inside caliper or some other precision measuring device, you have to make sure it has been calibrated recently, with traceability to the National Bureau of Standards, and measured in a minimum of 3 locations in each cap and connecting rod. Then I hope you're also checking it with plastigauge and comparing.
I don't really know why you don't trust plastigauge. I use it on my race engines whenever I need to build or rebuild one. I have never had a failure of any of my built engines thus far (knock on wood), although I have experienced a failure in a crate motor.
