Engine Assembly: Main Bearing Clearance

My crank was just machined but I still wanted to check all the bearing clearances just in case. I do not own micrometers or bore gauges so I had to settle for Plastigage. I've read that it is not that accurate but should be enough in my case as the machinist should have measured everything.

Before installing the bearings, I cleaned them and their bores. Then I cleaned the crank journals and finally pushed the bearings in place. After carefully setting the crankshaft to the block, I installed and torqued all but number one cap. For some reason Tom Monroes book says that before doing the measurements, all other caps must be installed. They should not touch the crank and so should not make any difference but I followed the instructions anyway.

I had a strip of green Plastigage that measures clearances from 0.001 to 0.003 inches. I cut a piece of it and carefully set in on the first journal.

Then I installed the main cap, tapped it in its groove and torqued the lubricated bolts to 65 ft-lbs. After removing the cap again, I checked how much the Plastigage had deformed with the supplied scale.

Bearing 1 clearance

Result was about 0.002 inches. Finally I cleaned the bearing surfaces and installed the cap again. Then it was time to repeat all the steps four more times.

Bearing 2 clearance

Bearing 3 clearance

Bearing 4 clearance

Bearing 5 clearance

Every bearing had maybe a bit under 0.002 inches of clearance. The acceptable range is 0.0005 to 0.0024 inches so I should be fine.