rpm drop with single pmag

I installed one pmag on the right side of a O-320. I get the same rpm drop on each side with the pmag and slick. About 60 rpm from 1800. The idle is rough on either side also but smooths out with both sides running. Is this normal for a one slick one pmag configuration?

That is not normal. You should see a very small drop in RPM whe grounding your mag.

How are you testing the P-mag? Grounding the P lead or dropping the power to it?

Do you have the jumper in, forcing it to the A curve?

Did you set the P-mag to TDC when you set its timing?

What sparkplugs are you using? If NGK's, are they solid caps? Did you gap them before installation? Who made the wiring harness?

Did you ground your P-mag to an engine case bolt or your firewall?

Yes to all of Bills questions. The harness was furnished by pmag. Grounded the p lead to test. Grounded pmag to engine case.

This is how much I get with mine or even worse on a IO360-M1B. Interestingly, I drop fewer RPM (around 60) with my Slick mag and it is a YES to all those questions asked by Bill with the exception that I have timed mine 1 or 2 degree pass TDC per recommendation.

Same here. When I had a Pmag on my O-320 E2D I got the same drop (~100 rpm) with the Pmag or the Slick on the other side. Tested by grounding p lead at run up, unit grounded to the engine case, solid terminal NGK BR8ES plugs gapped before install, timing set per instructions at TDC, jumper in, and self-made harness that was tested good by Brad himself. Lots of folks report zero rpm drop on their Pmags, but that was not my experience.

I get zero RPM drop on my Pmags. The EGT rise is the only indication the key switch is functional. That said, I do lean the mixture to max RPM during the run up. Typically, I'll see a 20-30 RPM rise from full rich - Then I check my ignition.

Of course, the EOR run up is just about worthless anyway - done more out of tradition than anything useful. The in flight, LOP mag check is where you really find out if the ignition is healthy.