Lots of great posts about this from the old experts on the old site. The recommendation usually was to follow the manual. 

Dave

@lou Lou, To answer your original question, The main bearings are removable shells and the rod bearings are poured in place.

Many years I owned an auto parts store and automotive machine shop. My machinist held the opinion that babbit bearings were too soft to get an accurate reading with plastigage. I have never heard this theory from anyone else but he was very capable and knew his business as an automotive machinist so I am passing this info along.

Mike

Thank you gentlemen, I will follow the manual!

Lou

@35mike I have published my opinion on the use of plastigage on the older Chevrolet bearing babbitt many times in VCCA Forums and literature. I wholeheartedly agree with your ex-machinist. Plastigage is only good for an approximation of the gap in those babbitt bearings. 

I also totally agree with the description of fitting the bearings by the manual. It has worked for me in the past 50 years should work for the next 50 as well. Everyone needs to understand that these engines are not manufactured with modern techniques and materials. Therefore, they should not be treated the same as today's engines. Yes, basic processes, machining, techniques can be used but understand that there are critical differences. Use of plastigage is one.

i vote for the old "feel for the drag, tap with the little ball peen" as well.

Even on newer stuff, I'm more inclined to use my micrometers and telescoping gauges.

The only time I would consider modifying the hammer tap method of setting the rods would be if the bearings had been re-poured with a much harder babbit,

in which case they may need to be set to a VERY light tap of the hammer.