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08-31-2012, 10:33 PM | #1 |
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Location: Brookdale,Ca
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Qjet Secondaries Stuck?
I have a 4MV Qjet, and there is some form of "linkage" in the lower passenger side that rests/sets against a pin that goes through the secondaries shaft(outside of carb). This does not allow my secondaries to open. I can physically swing it out of the way and that then allows the secondaries to open at full throttle (engine off).
As i understand it, the secondaries will not open in Park w/ engine running and throttling. Is this correct? My question is, does this mystery "linkage" swing away from the pin while I am driving, allowing the secondaries to open, or what? Thanks in advance! |
08-31-2012, 10:39 PM | #2 |
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Re: Qjet Secondaries Stuck?
It swings away when your choke is completely off.
Your secondaries will open in park or nuetral. There's 2 parts to the secondaries. The throttle plate in the base which opens mechanically via linkage from the primary plate. The door on top is the second part. Opens under load. You won't see it open while just revving it in park. Here's a link on everything quadrajet. http://www.digitalcorvettes.com/foru...ad.php?t=88376 |
08-31-2012, 10:48 PM | #3 | |
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Re: Qjet Secondaries Stuck?
Quote:
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08-31-2012, 10:51 PM | #4 |
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Re: Qjet Secondaries Stuck?
So if I let it warm up, choke off, I should be able to open the upper butterflies manually, have some one punch it a bit, and ill be able to see the lower secondaries open while in park, correct?
Thanks for the info! |
08-31-2012, 10:52 PM | #5 |
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Re: Qjet Secondaries Stuck?
Yes, auto choke w/ coil on manifold.
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08-31-2012, 11:35 PM | #6 |
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Re: Qjet Secondaries Stuck?
Warm it up. If the little arm is still stuck on the pin then your choke hasn't released completely. Push up slightly on the link arm coming out of the choke stove on your manifold and the arm should drop off. If not you need to make that link arm longer by bending it straighter. It is bent for that reason.
If your choke is all the way off just stroke the throttle and watch the pin on the passenger side to see if it moves. The pin is attached to the secondary throttle plate. It doesn't need to be running to see this. |
09-01-2012, 11:58 AM | #7 |
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Re: Qjet Secondaries Stuck?
Very nice. Thanks again gents! Ill have my cup and head down to peep it out soon.
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09-01-2012, 12:25 PM | #8 |
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Re: Qjet Secondaries Stuck?
Take a pic of it.
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09-01-2012, 02:08 PM | #9 |
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Re: Qjet Secondaries Stuck?
Well, all worked according to plan. that linkage comes off the secondary shaft pin just like yoos said.
Now, yesterday i replaced the accel pump, and after running for maybe 5 mins total, it is stuck down again. I got the standard replacement, and not the one I saw on line that has a retaining spring under the rubber plunger. I will pop the top off the carb again, and was wondering if I put a bit more sturdy return spring (which did NOT come w/ the acc pump kit) would that help fix. I cannot see how it would hurt? thanks in advance, again! |
09-01-2012, 02:21 PM | #10 |
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Re: Qjet Secondaries Stuck?
THe retaining spring under the cup is there to keep the cup sealed against the bore.
The other spring is there to push the plunger back up but also there to control the action of the plunger. Like a shock absorber. A stiffer spring might make the plunger pop up better but might screw up the absorber aspect. You could stretch it to make it a little longer. Do you have it in the right way? |
09-01-2012, 02:28 PM | #11 |
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Re: Qjet Secondaries Stuck?
I wouldn't expect the secondaries to open in park/neutral. Of course the choke linkage thing discussed above is correct, and it must be fully open to allow the seconaries to open, but even so, the secondaries are held shut by a spring. That spring pressure is overcome by vacuum (through the venturi) created in the primaries, so they only open when the primaries are experiencing significant airflow.
I doubt that your engine (or any engine) would "need" the secondaries to open in order to make enough power to merely rev the engine to redline in park. This is -not- a problem or a defect, it's the way it's supposed to operate. And unless you're on a dyno with a load, I don't think there's a practical way to verify they open without the car moving.
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09-01-2012, 02:37 PM | #12 |
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Re: Qjet Secondaries Stuck?
got it Dave, thanks. the link that stops the secondary throttle plates from opening DOES remove itself after warm up, and that was what i was most curious about. thanks again.
geezer. i do NOT have the retaining spring under cup variety, but more a stock replacement (no retaining spring). the return spring certainly appeared to be non-directional. I just placed it in its home, and set the plunger/shaft over it so the return spring was up inside the plunger. the accel pump rod on top currently sits about 3/8-1/2" lower than normal. i can pull it up as it is "free", but it simply drops back down. |
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