No, they weren't dyno tuned...
I know from talking to some old timers that they used to have engine run "hot test stands" at the end of the big block assembly lines where they would start them and run them for a short time 1 minute give or take to make sure they ran and to prime the oil system... Some people may have twisted that into saying that they were dyno tested...
They said that if the 440 6 pack engines were set too advanced they would shoot flames out of the center carb up to the roof... So sometimes the operators used to advance the distributors on them on purpose to see the "flame show"... You could see it from halfway down the assembly line...
When I was there we used a cold test stands after the long block was assembled and they spun the engine without firing it to prime the oil system and check valve timing events and oil pattern... They would fill it with oil, and could catch a rod with a plugged squirt hole, and see if the valves were opening and closing at the right time, and soft lifters, spark timing, gap on spark plugs (they could catch a closed gap), malfunctioning or improperly installed cam and crank sensors would also be caught... All information was stored in a database linked to the bar code on the valve cover for ID.... It was more advanced than starting an engine on the old style hot test stands... If anything was found wrong, they had cold test repair men that would repair the problem and then it would be retested until it could pass... If it couldn't pass the cold test, it would not be allowed to leave the cold test stand loop and taken off the line to be sent to the tear down department to be torn down and any good parts recycled... Cold test dtands were basically dyno stands the spun the engine over without starting it...
We also audited engines on a regular basis... One of each size engine that we made was put on a hot test stand in the audit department every day and ran for about 30 minutes, then torn down and inspected... Any defects found were rated on a scale of 1 - 10 with 10 being the worst... If we got a 10 demerit in audit, we had to immediately see what failed and report how it happened and how we could prevent it from happening within 24 hours of the failed audit... Then determine if any other engines made since the last audit could have that defect and quarantine them to be inspected to verify that they didn't have that defect before we were allowed to ship them... If not, we had to scrap them and tear them down and recycle any good parts...
Then the dyno lab in the factory would test one of each engine per week on an engine dyno for 10 hours... They had a program to run them at different RPM's some of which were acceleration from idle to max and another part was to do 30 minutes of wide open throttle... After the dyno test, the dyno lab techs would verify the torque on all fasteners on the engine while tearing it down and then inspecting it for wear... The horsepower and torque curves were then distributed to all engineers and managers at the engine plant and the design center every week...
All of the audit and dyno test engines were torn down and some of the parts were recycled and others were scrapped... They used natural gas to run them instead of gas because the natural gas was "dry" and we could recycle the fuel injectors etc after that instead of having to scrap them and treat them as hazardous material if they came in contact with 'wet' gas...
