Yes - it's a 6 cylinder 0300 - the left mag fires all bottom plugs and
the right mag fires all the top plugs.

Tony


In article .com,
wrote:

My O-200 Continental has the left mag firing all the lower plugs and
the right mag firing the upper plugs. What George says is true of
Lycoming engines where the mags fire 2 and 2. If indeed, the left mag
is firing the lower plugs, it could easily exhibit your problem. Pull
the lower plugs and take a look.
Tim (C-150M)