I fit the new thrusts into the block [not cap] and then measure the total clearance.[dial indicator ]
If it is less than .006-7" then remove the thrusts and and measure the thickness of each thrust[ micrometer .try to keep them the same thickness] and lightly lap the steel back on a flat surface. I use wet and dry on a surface plate[ flat piece of glass will do] Check that the surface is flat.
I use some bearing blue on the crank face and re fit the thrusts and check total clearance. Work out how much more needs to be removed to get the correct clearance. Then rotate the crank. Remove thrusts and see how much of the bronze face is in contact with the crank. Some times it might be just bearing in a localised area if the thrust is not flat.
I then scrape the bronze face at point of contact and repeat the process until it has a good surface contact. Make sure you do not take too much off and end up with too much clearance. If you can not scrape then use some glass paper and CAREFULLY remove the high spots. Do not use wet or dry as it will leave particals is the surface and cause wear.
At this stage you should have a flat uniform bearing surface and thickness of the thrust.
If the clearance is still not enough then take it off the back of the thrust.
Once the block thrusts are OK then repeat with the cap thrusts until you have the clearance on the cap thrusts .006" to .007" more than the block thrusts. IE the total clearance of block thrusts is 6to7 thou plus differencial clearance 6 to 7 thou . This will give a total clearance on the cap of 12 to 14 thou. on the cap thrusts.
This way the block side will take the load before the cap and when the crank flexes [ie bends either side of the bearing] the cap will then start to take some load as well.
Clear as mud
