bought a coil once, side of the packaging said "do not mount horizontally" I thought "whatever" and put it on my OEM coil mount bracket. within a week, I noticed oil pooling on the intake under the coil, and wondered where that oil came from. wiped it up.

about a month later the coil was shot.

bought a new one that was more expensive, but was able to be mounted in any position, and it lasted till I pulled the engine out for restoration