Yes indeed the Ford I6 and several other American I6's over the years use gears. That's why I pointed out in my post that OHV engines are good candidates for gears because the camshaft center is very near the crankshaft center. That means that one gear on each shaft is all that is necessary.

The way that Detroit has dealt with the noise problem with gear driven cams has been to use nonmetallic gears. This does not make for a super durable setup.

When the shafts are farther apart as in an OHC engine, it will require the use of several idler gears between the driving and driven gears. Again, this results in a build up of the slack in the gears. In the case of a OHC in a V configuration it will take probably 8 gears at the very least and that would be for a SINGLE OHC.

I also fully expect that the Rolls Royce engines you speak of were OHV or flathead engines. There again the shafts are close enough to require only one gear on each shaft.

Have a great day,