In the pictures, I see the engines mounted sideways. Talking to a lot of guys that built twins before, the back and forth motion of the pistons can set up a vibration that can cause one, or both the engines to quit on you!?! With both the twins I built, I mounted the engines so that they were mounted straight up and down. I never had an engine out on my twins. I will post a pic of my RCM trainer in a day or two when I have time. Cheers! 🙂