is this plug rich or lean? its the trailing plug

 

Trailing is hard to read because it has a small hole for the flame, so tends to look rich. That one looks lean to me but the leadings are the ones to look at.

 

It doesn't matter, because it's the wrong plug for the engine.

Mazda specifically designated the NGK BR7EQ14 or BR8EQ14 plugs for our cars because they will survive the high duty cycle of a rotary ignition system.

Link: https://www.racingbeat.com/RX7-1975-1985/Ignition/11530.html?id=WKXdDLmP

 

Yes get rid of those!!!

As Duck says. run the OEM spec NGK's. NGK Part Number is NGK 2329... get them from Rockauto, local parts store etc.

And new NGK cables, cap and rotor if they are old!

 

Looks like maybe an rx8 plug to me, should be fine as long as its NGK

 

I was about to say the same. It appears to be an rx-8 plug. As for rich/lean.. from what I can tell it looks normal?

 

I run RX8 plugs in mine but I have a strong ignition. Not sure the OEM ignition has the oomph to drive the RX8 plugs well.

 

Rx8 plugs were designed to be fired using High Energy Capacitive Discharge with coil on plug design. The 35 year old ignition systems in our 1st Gen cars is neither, and will quickly lead to fouled plugs, poor performance and crappy fuel mileage - hence my original post on this.