Mark Maras

@siteunseen Which one are you driving to Z Con?

I'd worry about old fuel first as well as your driving priorities.

It was 180ish psi last year. Something changed. Assuming the cam wasn't changed nor the cam timing, I'm guessing the valve lash is too tight too @jalexquijano Time to check the valve lash again if you're sure the 100 psi compression test was done accurately. Yes you have to. Valves that aren't closing all the way will be burned toast in a very short time. On the plus side, IF, the 100 psi was correct jumping it back up to 180 will feel like you slapped a turbo on it. After checking the valve lash do the compression test with the engine warm. Start with #1 and go thru all six, then test all six again to verify the first test results. A written explanation of the 100 psi compression test procedure might help explain the low numbers.

How is it doing these days when idling in traffic? Still overheating or loading up the plugs? Easy enough to add a hose but what "situation" is the mechanic trying to solve with the extended air intake? The compression test looks wonky to me. First, I've never seen identical compression in all cylinders in any engine. Second, If they're all at 100 psi, IMO, they're all low. My engine tested around 160 psi (+ or - 5 psi.) the last time I checked. is it possible the valves were set too tight?

keep in mind that "I just wish I could do the work myself" was the first step for all of us. If you have the space and time, go for it. Many of the Zs here have been rescued from becoming a parts car, most by owners who started off not knowing how to do the work and learning as the job progressed. Take it one step at a time and ask questions. You can do it.

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.

@Redwing

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.

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.

No open casket. Just an urn with a Z on it. The cremation will take place at the time of the accident.

Kathy and I will be there too.

I had to deal with Chinese steel products for around two decades. We normally bought steel wire from Tree Island Steel in Richmond, Canada and the quality was always excellent. Then about once a year the current knot head in corporate purchasing would buy a few hundred tons of Chinese wire at a discount and distribute the wire to the manufacturing branches with no prior notice. Surprise! Production plummeted when we tried to use the Chinese wire. The inconsistency was beyond belief. I was not popular with Corporate when I sent it back year after year. Might explain why everyone was smiling (including me) when I retired.

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..

When the door card is removed, feel around the bottom of the door on the inside to see if there are any stray fasteners that have come loose and migrated there. It was a common problem on my 71.

@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.

@jalexquijano Rotor and cap being new doesn't tell me what brand they are. Many new parts are a P.O.S. I do agree guessing won't solve the problem. Swap the #4 plug wire with another one or measure the resistance in all of the wires using a volt-ohm meter so we can eliminate that possibility.

Others have reported that the old standard tan color is not attainable with the fuel formulas currently in use. I can only assume that a much lighter tan color is what we're shooting for.

If the compression is good in #4 (as I recall, it is) and it's getting a decent quantity of fuel, (it is) the gremlin in #4 has to lie in the dist. cap, rotor, plug wire or plug. Multiple plugs have fouled so it has to be in the cap, rotor or plug wire. @jalexquijano What brand cap and rotor are you running? We changed my son's RX7 cheap replacement cap and rotor (the old ones still looked? good) to Bosch parts. Instant improvement in performance and it helped the original 12A thru another DEQ inspection in Oregon. The one thing I did notice when installing the rotor was the precision fit as compared to the old one. Not one degree of sloppy fit. Something to consider.

@jalexquijano Try some different weight oils in the carbs. It would be an easy, fun experiment. (until one drops a piston or dome, VOE, be careful) I ran Marvel Mystery Oil in mine for a few years and then switched to ATF. Both worked fine with no noticeable difference in performance. Try a light weight oil as well as a heavy weight and tell us what you find. Jalex deserves the credit. He tried to solve this problem for quite a while (possibly from day one) and never threw in the towel. My small part in this was to keep Jalex FOCUSED on what WE theorized was a float level problem. I don't think any of us are totally convinced that Jalex's floats are absolutely correct but they must be close. Jalex asked a question earlier and knows these carbs well enough now ☺️ that he and I are curious what effect raising the floats 1 mm and raising the nozzles 1 turn (1 mm, 2 1/2 turns down) would have. I don't know for sure. I believe the nozzles are around 3 1/2 turns down at this time. Opinions and theories are welcome from all.

After running it through the gears at WOT and the engine won't rev to high RPMs under a load, will it rev to 6 grand in neutral? I'd let the engine idle, shut it off and pull the domes and pistons. Then pull the choke lever back and determine the fuel level in the nozzles. You should be able to see the fuel level with the nozzles pulled down. After determining the fuel levels, reassemble the carbs and run it hard until it cuts out. Shut it off immediately and pull the domes and pistons again. Pull the choke lever back to drop the nozzles and see if the fuel level is substantially lower than before. That should prove or disprove that fuel starvation is the problem.

You want it to run best under normal driving conditions which, I'm assuming, is a daily driver. It sounds to me like it's running pretty darned good. No need to go out and run the engine hard just to check the plugs. You can, however, go out and run it hard to have fun. As long as you share your fun with us. Pics are nice, videos are better. I'd like to hear it run.

They don't look too bad although #4 is still the odd one. I think I'd try swapping #4 plug wire with another wire to see if the problem moves with the wire. What is your over all impression of the way it's running? Any problems idling for long periods of time? If I was running your engine build, I would expect to have to blip the throttle now and then to clear the plugs at idle. Backfiring in the intake or exhaust? Misfiring at any RPM?

A little more info would help. Is the problem ongoing? I'd start with a complete tune-up. Did you fill your tank at the same gas station after the previous successful fuel treatment. They could have water in the bottom of their tanks. My Dad would never stop at a gas station that had a tanker sitting in the lot. He said filling the underground tanks would stir up the water sitting in the bottom of the tanks and allow it to be pumped into a vehicles tank.

@jalexquijano Is there much difference in spark plug color when you compare #s 1-3 vs 4-6? Let's try to figure out if one carb is running richer than the other.

Unless one owns a multi task CO2 extinguisher that will also chill beer.