FWIW, to me, "blueprinted" means rebuilt to original factory "blueprint" specifications.
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That can be a real misnomer, because most factory engines aren't "blueprinted". Their factory specs are very wide from the high to the low tolerance and simply refitting the engine back to fit that range or those specs isn't blueprinting. In the racing world, blueprinting is many steps beyond what the factory delivered. Blueprinting a race engine means you tighten up the factory specs even more to a much more consistent and a more specified size for all the components, such as. For your bearing clearances for example, the factory specs may allow a range of .0005"- .0035" as acceptable. In a race engine that is blueprinted, you make all the bearing clearances the same exact size, such as .0025". This is also done by making all the journal sizes on the crank the same size on their respective rod or main journals, and making all the rod housing bores the same size with no taper or out of round, and the same for the blocks main housing bores, etc. Then you install the bearings and use precision measuring dial bore gages to verify and confirm these clearances around the entire ID of the bearing surfaces as well as the front to back length of the bearing surfaces. Then the cylinder bores are given the same treatment and all the pistons have the exact same clearances placed on them. Using a torque plate also is required to achieve this level of "blueprinting" status. And then the same is done for the wrist pin fitting, and valve guide honing, etc...So as you can see it's a much more involved process and elevates the cost of the engine over the cost of the plain rebuild by quite a bit. Its common for many rebuilders to use the "blueprint series" or similar moniker to define some level of precision above a stock rebuild that they perform, but whether they actually are skilled enough or have the necessary equipment to perform those elevated levels of precision they are claiming remains to be seen.
