I can try this test. Distributor cap and rotor are not ngk believe me. Its some aftermarker brand cap and rotor i bought 2 years ago.

Attempting to coax our 12A rotary 81 RX7 thru another DEQ check we bought a Bosch cap and rotor for it. The previous cap and rotor were "some aftermarket brand" too. The DEQ exhaust readings were substantially cleaner after those two Bosch parts went in. If you do change the cap and rotor, move #4 plug to another hole or put in a good clean plug from your ever growing stash of plugs..

On 5/30/2018 at 4:22 PM, Mark Maras said:

@jalexquijano Valve stems and valves? I don't recall anyone talking about them. All I'm asking is remove #4 spark plug wire and use #3 or #5 in it's place. Use #4 wire on #3 or #5, whichever one will reach. I would also swap #4 plug with #1 or #6 plug to remove the dirty plug from the test area. No money and only a few minutes to do it.

 Oh yeah, and I'd still like to know what brand your dist. cap and rotor are. NGK wires are a good choice.

Okay. As a recent update, after 2 weeks of not driving my 240z due to business trip to Athens, i decided to crank the engine yesterday, with the choke pulled to 3/4 for 45 secs and once the engine warmed i took to 100 mph at the highway. No backfire at the intake or at the exhaust even when releasing the gas pedal at 2nd gear going down hill. Nice aceleration. I took some pictures of plugs 4 and 2 for your ready reference. Do you think they look good? Or should i open the floats again in order to attempt to get the 1/16th below the nozzle at 2.5 turns clockwise? The actual measurements are the following: 3.75 turns clockwise for the front carb and 3.65 turns clockwise for the rear carb. 

Looks good and sounds like your earlier issues are resolved.  Now, just enjoy the ride.

Dennis

 The plugs look pretty good. #4 still looks like the ground electrode has a bit more carbon than #2. You report that the engine is running good. Congratulations on a job well done. Re-adjusting the floats and mixture screws all depends on your curiosity level. You could end up making it worse and have to return to the current settings. That would be OK too. At least you'd know for sure.  Personally, I'd drive it until I either didn't care about re-adjusting them or until my curiosity drove me to try raising the floats and mixture screws. Nice that you have the option.  If you do re-adjust the floats and mixture screws, be sure and report back on your findings. The more you screw with them the more you'll learn. 

 Did you replace the generic cap and rotor with quality parts? I still think that may be the problem with #4.

Which one should i buy? Bosch brand only?

 I'm sure there are other quality brands out there. Perhaps others can advise on those. I haven't bought caps and rotors often enough to know which brands are best. I do know the Bosch cap and rotor made a significant improvement in performance and may have been the deciding factor in getting the RX7  thru DEQ again. A bit expensive when compared to other brands. I did notice the Bosch rotor precisely fits the dizzy shaft. It looks like the rotor was machined to fit the shaft. I've seen a few degrees of slop in cheap rotors. I'll never go cheap again.

I'm partial to the ones that have brass contacts, I think they conduct better.

https://www.rockauto.com/en/parts/standard+motor+products,JH66,distributor+cap,7120

https://www.rockauto.com/en/moreinfo.php?pk=46494&cc=1209169&jsn=366

Me too on the brass, they last longer.

Jalex if you have upgraded to the E12-80 ZX dizzy they're a little bigger in size so don't forget that when ordering.

I have the original old hitachi dizzy

20 hours ago, Mark Maras said:

 I'm sure there are other quality brands out there. Perhaps others can advise on those. I haven't bought caps and rotors often enough to know which brands are best. I do know the Bosch cap and rotor made a significant improvement in performance and may have been the deciding factor in getting the RX7  thru DEQ again. A bit expensive when compared to other brands. I did notice the Bosch rotor precisely fits the dizzy shaft. It looks like the rotor was machined to fit the shaft. I've seen a few degrees of slop in cheap rotors. I'll never go cheap again.

Should i purchase these ones? They dont have brass terminals.

 I'd buy them. I like the idea of brass contacts too but in reality there is only one "contact" point in the center of the rotor. The precise placement of the rotor and the precise air gap between the rotor and the plug wire  "contacts" are the critical factors IMO.