I’ve seen it twice in my lifetime where the factory timing chain was not marked correctly and the timing was off. In both cases, it was retarted. One was on one of my 340s I installed in a truck. It had no low end torque but ran like a scalded dog after 3500 rpm. I built it before I knew anything about decreeing a cam. I degreed it when I pulled the motor and installed it in a car. With the marks lined up properly, it was 8 degrees retarded. Then a friend was building a 340 and noticed the piston was way down the hole when he was lining up the timing marks on the chain. He called me to degree it and it was off one tooth and 16 degrees! That 340 had always been a dog. I used that knowledge when I built my jr dragster motors. I retarded my big 7.90 motors ( 3 x 3.5) 4 degrees. It kept them from spinning the tires at the hit but they ran 88 mph at the stripe. They would pull hard on the big end. I sold one motor to a friend and he sent it off for a rebuild. It slowed down 4 mph!