Lycoming Oil Sump Clearance on the RV 10 Engine Mount

A concern that comes up with different variations of the Lycoming IO 540 is will the oil sump clear the lower cross tube on the Van's Aircraft motor mount? The tube in question is pictured to the right and is the one that runs between where the two lower vibration mounts bolt on. This has become a big enough issue that Van's wrote a service letter on it: RV-10 Engine mount/Engine interference.

As you may recall the Lycoming IO 540 C4B5 I'm working with is from a Piper Aztec. The good news is there is no interference issues with this engine. The clearance was right at 3/8". I'm not sure if all C4B5 use the same oil sump, but the right engine on a 1974 Aztec works just fine:)

If there is interference there are two fixes I have heard about primarily through the Matronics RV 10 e group and these are: 1. get a different sump or 2. cut out the tube and weld in a new one that is bent to clear the oil sump. I'm just glad it was a non issue for me! If you are not familiar with the Matronics RV-10 Aircraft group check it out. It is a great resource: Matronics sign up