Uneven mag drop

[wolftimj]

Chasing a problem on a new Lycoming overhaul IO-360A3B6D (roller tappets). Almost a year on it and just past 200 hours. It has a problem with one mag, or one side, dropping significantly more than the other at run up. The mag that cam with it was found to have almost no point gap so it was changed for another freshly overhauled unit. It runs better but still not an even drop. 8 new champion fine wire plugs, no change. Things left to check seem obvious enough; the harness. Any other ideas?

Tim Wolf

[Barry]

The timing of one mag could be a little off. How much is the difference ?

[fantom]

Quote: wolftimj

Any other ideas?

[N201MKTurbo]

When I do the internal tining on my dual mag it usually takes me an hour or so to get them even. If you just do it by the book with the factory holding clamp it is hard to get them dead even. I usually rotate the mag by hand and make fine adjustments of the points until both lights come on at exactly the same time. baring any plug/ harness problem this usually gets the mag drop difference to zero.

Do you have a misfile on any plugs?