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882993md

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882993md last won the day on February 19

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About 882993md

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    Rockville, MD
  1. I did bump the pedal and the idle increased by a couple hundred rpm when sitting at a light. I reached down and pulled on the pedal and it moved towards me (maybe 1/16th of an inch?) and the idle returned to normal. I see some slop in that plastic spherical bearing, but I can’t see anyway of replacing it. Howard
  2. SOLVED!!! (And Happy Easter!) I just came back from a 30 minute drive and no more idle surge of any kind. I don’t know if it was the vacuum leak or the floppy unsecured throttle rod (or a combination of both) but the car is a pleasure to drive. I pulled plug 2 and 5 and if wondering if someone may provide feedback. I’m at 2 1/2 turns mixture on both carbs. Howard
  3. Hi everyone: I haven’t had a chance to drive the car due to busy work schedule. However I did take some time to look at the mechanical parts of the throttle links. I checked both throttle return spring‘s on the SU’s and they are new and are very strong. The only thing I could think of is something is mechanically preventing the butterfly’s from returning to resting position, or unwanted air is entering the system. I did find missing pieces on the throttle arm. I believe there should be a spring, washer, and cotter pin? It was mentioned that a vacuum leak may be the cause of the surge to 3000 or 4000 RPM. I don’t have that many vacuum lines on my system. I have new lines coming off the brake booster to the balance pipe. I double checked those connections and they are good and tight. I have the vacuum line from the vacuum advance to the front carb. Hose is in great shape and connections are tight. Finally I have the heater control flap line also going to the front carb. I checked that and found the end had split. Apparently this tube is too small of a diameter to go on that carb. vacuum nipple. I have capped off that nipple for now. I’m going to run to the store for a spring and washer and cotter pin then take her out for another test run. I also turned the mixture screws up back to 2 1/2 turns each. When I was trying to set the the mixture it was about 30° outside. Now that we have some 60° weather the car started easily at 2 1/2 turns. I cleaned the spark plugs and once I have the above parts installed I’ll drive and report back with results in a few hours. Howard
  4. Thank you I'll try this tomorrow Howard
  5. I'll try it tomorrow and report bank Howard
  6. Hi: I've been driving my car and adjusting the jets and checking the spark plugs after my first attempt at tuning the 3 screw SU's. When shifting gears the RPM will sometimes not drop and I have to blip the throttle to get it to go down. I have my idle set at ~750 rpm and timing at 10 degrees. My plugs show I'm running very rich and I'm four turns down on the mixture for each carb. Would the stuck/surging idle be a mixture issue, or would that be a mechanical possibility somewhere in the throttle chain? I did sync the carburetors at idle and at 3,000 rpm. Thank you. Howard '74 260z
  7. I used the clear tube on the rear carb to check the fuel height and it seems I'm actually a little high by 1.5-2mm (I didn't bother adjusting the float at this time). I started the car with choke and the rear carb was backfiring until the car warmed up and I synced them using the (snail type) synchronizer. At roughly 1,040 rpm both carbs were synced to the 12 mark. I tried to get the rpm down to 750 but then the carbs would go out of sync with the front at 5 and the rear at 11. Lift the rear pin-slight decrease in idle to approximately 950rpm Lift the front pin-immediate stall Both jet adjusting nuts at 2.5 turns. I checked plugs 2 and 5 and both were black. I cleaned them but forgot to check them again before calling it the day. I will check tomorrow. Howard
  8. Crazy busy last few days no time to work on the car until today. I did spray carb cleaner on both throttle shaft bushing and no change in engine rpm. Howard
  9. David when I lift the pin for the front it stumbles then recover. When I lift the pin for the rear the engine dies.
  10. ok here are the results. I attempted to get the rear carburetor running (stumbling along) with the front disabled and I couldn't. Even with full choke it will run really rough for a few seconds and quit. I again checked the fuel level at 10 turns down and it now it was way low by 3 to 4 mm . I bent the float tab down (it is now much lower than the front tab) was able to get the fuel right at the opening after two tries. I tried to start it again on just the rear and same result-stumble for a few seconds then quit. I had the mixture at 3 turns for the rear and 2.5 for the front. I enabled the front carburetor and the car started with no problem. I noticed the following with both carbs running: -Rear carburetor is sucking A LOT of air versus the front (sounds like a jet almost) -Rear carburetor was back firing. When I blipped the throttle at the rear it back fired even more. Howard
  11. Just want to make sure I understand... You mean that you increase the idle on the rear carb and the overall idle speed goes up. But even after doing that, if you disable the (FRONT) carb, it shuts down immediately? Yes that is correct How much did you raise the idle? Maybe you just need to go a little more? Depends on how far out of balance the two of them are. Open the rear carb some more, and then close the front one to compensate and bring the idle back down to where you want it? I went up two full revolutions on the #10 screw. What happens if you push on the linkage for each carb independently Does the engine speed come up about the same for each? When I do that the rpm's do increase but I noticed that it's not quick and instant like in the past. It seems sluggish for each but the rpm's do increase. I'm going out outside now to try again. I will see if the car will start with the front carburetor disabled and try to get the rear to idle. Howard
  12. When I hold my hand over the mouth of each carb the engine will stumble then recover. The suction was about the same for each carb. If I leave my hand too long over the mouth the engine will die. If I move my hand away fast enough it will stumble then recover. I tried increasing the idle on the rear carb. When I restart the engine the idle is high but as soon as I disable it shuts down immediately.
  13. Hi everyone: I spent three days using the 10 turn down method to set my float levels. It’s maddening but I was so happy when I finally did it. I'm trying to set idle and sync the carbs. Both jets are set at 2.5 turns. I am able to get the engine to stumble along when I disable the rear carb. However when I disable the front carburetor the engine quits immediately. I lowered the rear jet by a 1/4 to 2.75 turns and still quits. Lowered rear jet to 3 turns and still quits. So I took off the rear dome and turned down the jet ten turns to check the float level. The fuel level is just a hair below the opening. I called it the day at that point and now I’m hoping for some insight. Thank you. Howard 1974 260z
  14. Hi everyone, I took off my needle valve on the front carb to clean and I stupidly dropped the brown washer into the engine bay. I have searched under the car and inside the engine bay (in the nooks and crannies) for one hour and I can’t find it. ☹️ Does anyone know if this is a ztherapy only part, or would a Napa or Pep Boys stock the washer? I was hoping to have my car on the road tomorrow and now this happens. Howard ‘74 260z
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