Excessive vibration

[mshac]

I do find it very odd that your bird has two new three-blade props, a fresh rear engine, but no engine analyzer? Priorities, my friend. You could determine your problem almost instantly if you had one installed.

IMHO this has nothing to do with the props.

Cold plug from #2 cylinder should be your main clue as to what is actually happening.

The following steps are recommended:

1. Compression test for #2 cylinder - If it checks out OK, go to step 2

2. Clean & inspect fuel injector. DO NOT STICK ANYTHING INTO IT! You may want to swap injectors from another cylinder just to see if the problem follows the injector.

3. So by now you've verified fuel and compression. The last variable is of course spark. From your report, the right mag may be weak. You don't say if they were OH'ed with the engine. Likely time to send them both out for OH.

Following these steps will resolve your issue.

As an aside, one of my V8 work trucks has a bad coil, so only 7 of 8 cylinders make power. Of course, there's roughness from the missing power stroke, but also from the fuel that was supposed to burn in the cylinder exploding in the exhaust pipe instead. Point being a cold cylinder will cause roughness in more ways than one.