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76Datsun280z

quick air regulator question

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I was curious on how far the rpm's should go up when the engine is cold and has the "fast idle" for a minute or so? Mine will goes up to about 950rpm's and it just seems a little low. Is this what it should be at when it's warming up? I think you can adjust the air regulator with the nut on the side the rpm's of when it's on the "fast idle" but need to know what to set it at, other wise I'll probably end up buying a new one.

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When I fire my engine up it will burst up to about 1400rpm, and slowly come back down to about 750 after about fve minutes. This is where it stabalizes when the engine is fully heat soaked. My throttle valve is a twin butterfly progressive and it has an air bypass screw directly on top that adjusts the bypass air, do you have one of these. I believe the one with the lock nut on the side is a factory min bypass for throttle position (should not adjust).

hope this helps

Cheers

Steve

:)

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My regulator was frozen shut, so I went to my stash of spare parts and found one that was open. I gave it 12V and watched to see if the orifice would close properly and then reopen as it cooled. Sure enough, it worked, though when fully cold, it was only open about 1/3 of the way. With it open that amount, my idle now increases by about 150 RPM to start with and slowly drops back to ~800 when fully warmed up. Though I would like it to raise a bit more that this, 150 RPM is enough to keep the engine running smoothly and it no longer stalls when the throttle is closed when approaching a stop. This was a problem after I disabled the BCDD. Before I plugged the air passage, the BCDD would cause the engine to race whenever I slowed to a stop. It did drop at 10 MPH as it should, but hung at high RPM way too long. After plugging it and installing a working AAR, the car runs great and has just the right amount of throttle hang. It doesn't drop too quickly, yet doesn't race either.

I suggest that you remove your AAR and take a look at the opening to see what it looks like when cold. Next, hook 12V to the connector (I used aligator clips wrapped in tape so they couldn't touch each other) and make sure it closes after a few minutes. Hold it up to the light after it has closed and make sure it seals completely. Next, let it cool completely and see if it reopens again. Did the valve open all the way? If so, it's working properly and there is no need to replace it. Of course you already ordered a new one, so you could just go ahead and send the new one my way. :laugh:

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I actually have taken it off and cleaned out via. instructions off the internet which were spray it all out with carb. cleaner and to then soak it in warm water and to dry it out. I did that and also stuck it in the freezer to see if it would close which it didn't and it didn't seem to help it none.

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Hrm, I don't want to hijack a thread, but I think I might be having a problem with my AAR as well.

My car will idle at a high RPM for a while when it's cold, but then all of a sudden, it'll drop down to like 650-600 and just sort of bounce around and run very rough... as though the AAR isn't doing it's job long enough or something?

I had to adjust the idle bypass screw to make it idle decently when it does this.

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