Slightly off topic but Even cams can be out
We helped a guy recently, running a weber he had massive stand - off at certain revs [ petrol 'cloud' ouside the carb ]
and torque was way down on what was expected. After a lot of checking, head scratching, measuring and remeasuring
The cam that was ground wrongly with different LCA's on different pairs of lobes...Ultimately meaning the timing was probably only correct on 1 cylinder ??
I have recently known crank journals to be 2 thou tapered which came down to an uncalibrated grinding machine.
Precisely why I haven't used 'that place' for the last 35 years despite them being the nearest, could give you a long list of horrors from the 'that place'. PM me for a forewarning.
Its safe when engine building to assume nothing and check everything twice at least, and that includes your own measurements
Nick has the right idea....that way its their responsiblity, [ be it an engineering shop or engine builder ] to do the engineering and make sure its correct as they build it. By keeping it "in house" makes so much sense for any customer, it may not be the cheapest route but cheap is never usually good. It only needs one small mistake or mismeasurement and an engine and gearbox can be toast. ATDATT [attention to detail all the time] not quite OCD but near.
I was reminded of this recently when running a MINIstox race motor on the engine dyno....mine ran perfectly and another guys was not even fit to run, the flywheel bolt having been over torqued and damaged the crank, his pigeon never ran, mine flew.