The DB 610 engines did have considerable problems in development. Some of the problems were involved with vibration and resonance. The firing order was changed to suit the needs of the engines in the coupled version. Interestingly, the firing order was changed with the same crankshaft. This was possible because it is possible to swop the phases of two of the three planes in a three plane crank of a V12 4-stroke. So, the 1,8,5,10,3,7,6,11,2,9,4,12 firing of a standard DB 605 was changed to 1,11,2,9,4,7,6,8,5,10,3,12 order of a DB 610, the cylinders being numbered 1 to 6 on the right bank from the front and 7 to 12 on the left bank from the front. You can see that the 1,7,6 and 12 maintain their order but, the 8,5,10,3 and 11,2,9,4 groups swop their firing positions and so exchange their firing stroke for their inlet stroke. To do this, the camshafts, the magneto wiring harness and the fuel injection pump plumbing was all changed to suit the different arrangement. Of course, there were effects on the intake air flow distribution but, these must have been acceptable. Interestingly, the timing of the firing is offset at 30 degrees between the two engine components of the double engine, which means that firing impulses to the reduction gear are evened-out at every 30 degrees.
When the He 177 program was scrapped, many spare DB 610 engines were split to use the LH "X" component engine as a DB 605 A. These engines retained the 610 firing order and components and had a large stenciled Red paint warning to groundcrew about their 610 firing order etc.
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