Here's some replies I received so far (these were Chrysler engineers who were in the thick of all things racing & high-performance back in the day):
Hot test at M&I.Early Cross ram A990 motor.
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For what it’s worth the Spark plug wire boots look like early 64/65 race Hemi that are total different than 66 up street Again the picture is not that clear on my I phone.
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I’ve guessed about this before, I’ve always thought the early gen two engines where built in Marysville at the MCI plant. This looks like 64, carter carbs and K heads. It’s a hot test stand. Probably no load and I have no idea what kind of instrumentation they had on it. I know at Trenton, when Al Nichols worked on their hot test set up, they had lots of pressure and temp channels to make sure all was good to go. And of course, look for oil and coolant leaks.
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I’ll second Greg’s thoughts. I have seen this picture before, as well and the consciences is this is a hot test at M & I, where some of the Hemis were built.
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Couple more updated comments that came in - interesting stuff:M&I stands for Marine and Industrial. They were originally located in Marysville then later they moved to Beaver Dam Wisconsin. The engines that came out of there were always a little suspect. They never had the QC that the real engine plants had. They typically took stock engines from the plants and up fitted them for marine, forklifts, cranes, etc. in the case of the Hemi’s, they started with just the parts and assembled them. Later when the street Hemi came along, they were built at Trenton engine plant.
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At Highland Park there was Room #30 in building 136 where car test engines that were built in the Motor Room were sent to get tested. They were hung from a steel bar attached to a chain. Water and oil and gas and electrical were then hooked up to the engine and the engine was run to check for leaks and any other problems. There was a blue light we would use to check for oil leaks when the lights were shut off in the room. Then someone from the Balance Lab would come in and check the rotating balance of the engine and add weights to the converter if needed. This was all done before the engine was sent to Road Test Garage before the installation of the engine in a car. We used to call it a hot test.
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