Join Date: Aug 1998
Location: Waldorf Md. USA
I dont know how a "mechanic" could determine if the crankshaft was not balanced properly. The only way to do this is on a crankshaft balancer with bobweights clamped to the crankshaft.
As far as the size range on the crank journals, there is a range of allowable sizes. Most crankshaft grinders try to grind the crankshaft in the middle of the range. This will generally give you ideal clearances if everything else in the motor is correct. Ask your "mechanic" exactly what size the crankshaft is and post his answer, I would like to see it. Like Glenn said...has he actually measured the clearances ? If so, how ? Ask him these questions and see what type of answers you get. If he has not actually measured the clearances, then he does not need to be assembling an engine for you in my opinion.
I am a bit biased, and probably leaning towards the machine shop's side, but there are many things that can make a crankshaft tight, your "engine builder" should know how to check these things. He should be able to explain to you exactly how he checked them and what his results were. I am not going to give any clues, he should be able to give you the answers.
If you don't trust the machine shop as to the size of the crank, get a second opinion. Mistakes can happen. Most machine shops will probably check a crank for you no charge, I know I do most of the time.
Let us know what you find out,
Advanced Automotive Machine
1971 Chevelle "Heavy Chevy" original owner
1973 Z-28 ..one family car...Brother bought it new in 73