Mark Maras

Before you change to SM needles, check the float levels. The symptoms sound like low fuel levels in the bowls to me. The float levels are the primary mixture adjustment. The nozzles are the fine-tuned adjustment. @siteunseen I remember you altering the ramp angle on the float tang. Could that be the problem here?

If they still made affordable cars that are fun to drive (Miata for example), young people would learn to drive well and love it. Sadly, our oldest son and our daughter both started with a Camry and a Corolla. They still drive boring cars. The good news? I came to my senses and started our youngest son with an 81 RX7. He likes fun, fast, small cars to this day, and loves to drive.

I'd mark a ring gear tooth and the input flange. Then count the number of flange turns it takes to turn the ring gear one full turn.

Try 0000 steel wool on the water spots.

I had a 521 pickup that had corrosion on every electrical connection I could see. I disassembled each connection (grounds too), wire-brushed them, and sprayed them with Caig DeOxit. Everything that had previously worked intermittently or was dim, worked like new.

@jalexquijano Yes, carb cleaner and a brass brush will be fine. Don't change to new plugs of a different heat range yet. Let's concentrate on one change at a time. Raise both nozzles 1/4 turn, drive it for a few days, and report back with plug pics and a performance report. I'm still curious if you're using anti-seize on the plug threads and what color it is, silver or copper.

When it starts to run out of power at 4k, step on the throttle, and ease the choke on. If it's lean you'll feel the improved performance. It will also verify the lack of power is a lean condition.

@jalexquijano I wouldn't adjust the floats yet. IMO the plugs should be a bit lighter colored. I'd reduce the number of turns down (raise the nozzles) in 1/4 turn increments and drive it for a few days then look at the plugs again. If and when you reach a point when the engine isn't pulling as strong as it did before the previous nozzle adjustment, accelerate up a hill, and ease the choke on, If the engine is running lean you'll feel the instant power surge with the added choke. The choke is just lowering the nozzle the same as the mixture adjustment screw.

I shudder when I think of the number of spark plugs you've bought over the last eight years but unless you can get them clean (snow-white porcelain) a new set will get a fresh reading (Deja Vu) and hopefully narrow this down to the fuel-air mixture or oil. Did the plugs start to load up when you were waiting for your roasted chicken lunch?

Can you pin down "periodically"? Maybe a smell, RPMs, road surfaces, speed, any accessories turned on, hot fuses, or insect access points?

I'd clean the plugs before the test. You're looking for high resistance in one or more plug wire circuits. Measure from inside the cap to the center electrode on the sparkplug. Please post the results. Although I used liberal amounts of silver anti-seize on sparkplug threads for over 50 years without a problem, I always had that nagging feeling that one could use too much and screw up the electrical continuity between the plug and head. I recently discovered that the nagging feeling was correct. I guess I never used too much. Gundee is correct. Use the copper-colored anti-seize on sparkplug threads and likely it's good for everything else too. I just bought my first can.

And I want to know if you're using anti-seize on the sparkplug threads.

When centering the needles, screw the nozzles all the way up to the top. If the needle encounters resistance at closed throttle and you can't get it perfect, lower the nozzles to the running position (2 1/2 turns down) and it's likely they'll be fine.

@jalexquijano Modified test plan. Perform the test as described above except don't unplug the plug wire from the cap. Remove the cap with the wires intact and measure the resistance from inside the cap to the positive electrode on the plug.

@jalexquijano Thanks for the needle pics. It appears the needles are set to the same depth. I can't be sure about the float levels without some sort of measurement but they appear to be the same height😊. Let's assume, for now, that they're correct or close enough. Last year, when #4 was fouling, I had convinced myself that the problem was somewhere in the rotor, cap, wire, or plug connection because all parts were new and of good quality. Now the problem seems to have spread to 3 cylinders. One question. Are you using anti-seize on the plug threads? As I recall you have a multi-meter. Unplug the #1 plug wire from the plug and cap. Remove the #1 plug from the head and plug the wire into it. Measure the resistance from the cap end of the wire to the spark plug center electrode. Log it on paper and reassemble #1. Now go through the other cylinders and log those too. I can't tell you what they should be. What we're looking for is a glaring difference.

We need to confirm the needles are installed in the pistons to the same depth. Measure from the piston bottoms to the tips of the needles. No need to unlock them and change their height if they're the same.

@jalexquijano As mentioned above, check that both needles are installed to the same depth. If they're not, it would explain needing an extra turn down on one carb. The other possibility is one or both floats aren't adjusted properly.

@jalexquijanoIMO, it looks like the rear carb is too rich, and the front carb may be too lean. Both nozzles down 3 1/2 turns. I'm left with the float level(s) being wrong. @siteunseenCan the difference in the later lids be a possibility here? I've only dealt with the early lids with identical float hinge bosses.

I'd try BP6ESs.

Obviously, the plugs are still dark. Two questions. Did the plugs clean up well and is this all new fouling? How well did it run at 2 1/2 turns down?

If the floats are correct and I believe they are, 2 1/2 turns down should be close. I seem to recall yours being 3 to 3 1/2 turns down.

Replace or clean them. If the engine is running stronger with the wire change, the carboned-up plugs may (hopefully) be too much fuel. How many turns down are the carb nozzles?

@jalexquijanoI agree, time for new plugs. How many turns down are the carb nozzles now and how much better did it run?

@jalexquijano

@NocturnalEmber What was different when you said "slightly different positioning"?