4MV Quadrajet 4bbl choke linkage missing need diagram showing how to mount on carb - Hot Rod Forum : Hotrodders Bulletin Board
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Old 11-23-2010, 11:54 AM
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4MV Quadrajet 4bbl choke linkage missing need diagram showing how to mount on carb

Can anybody show me how the secondary lockout and fast idle cam linkage goes together on 4MV Quadrajet please?
The carburetor is missing the vacuum break assy. I had manual choke cable hooked up running to dash. Had to rebuild carb, and wasn't paying attention when I disassembled choke linkage. Now I'm having trouble figuring out how these 2 parts work/go back together on carb. Was working great until I took it apart. Put it back together, but fast idle isn't working now. When I pull knob on cable, it closes flap and kills engine.

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Old 12-01-2010, 07:03 AM
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There should be an exploded view in the instruction sheet from the rebuild kit.

In any event, http://www.newagemetal.com/pages/Che...vy0181_jpg.htm is a diagram. Search the pages - http://www.newagemetal.com/pages/Chevrolet/75/index.htm for more/different views.
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Old 12-01-2010, 08:51 AM
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4MV Quad choke linkage

Yes, there is an exploded view, but that doesn't show me how the secondary lockout and fast idle cam go together and are setup.

Thanks for links.
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Old 12-01-2010, 10:43 AM
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The lockout looks like:

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Old 12-01-2010, 01:01 PM
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4MV QUAD choke

How does fast idle cam work with lockout?
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Old 07-31-2011, 09:36 AM
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Any luck?

I'm looking for such a photo or diagram too of of the secondary lockout, fast idle and choke linkages all go together. Did you find one?
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Old 07-31-2011, 02:57 PM
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The vacuum break (some Qjet carbs have two) has to be functional for the fast idle and choke to work correctly.
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Old 07-31-2011, 03:46 PM
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Old 08-01-2011, 06:25 AM
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Check out the photos on posts 63 to 65 on page 5 of the thread "Rochester Quadrajet 4MV Carburetor: Removal, Disassembly, Rebuild (Rookie Level)".

If you still need more detailed pictures, I believe I still have the originals unedited, along with two 4MVs that I can always photograph again if more angles are needed. Hope this helps.
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Old 08-01-2011, 10:23 AM
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Quote:
Originally Posted by Gofastr
I'm looking for such a photo or diagram too of of the secondary lockout, fast idle and choke linkages all go together. Did you find one?
Check further down on this thread, there is some info, and pictures that might help you.

I have mine working better, and have all linkages hooked up. Still haven't figured out the secondary [won't kick in], but probably just as well [if I kicked 4bbl in, my bed would probably fly off truck].

Main problem I'm having besides secondary, is I have to pump gas pedal 7 or 8 times before truck will start.

Here are a couple pictures of what I have so far.
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Old 08-01-2011, 10:43 AM
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Quote:
Originally Posted by slowboy
Still haven't figured out the secondary [won't kick in], but probably just as well [if I kicked 4bbl in, my bed would probably fly off truck].

Main problem I'm having besides secondary, is I have to pump gas pedal 7 or 8 times before truck will start.
Secondary actuation:

Be sure the secondary throttle shaft is turning when you open the throttle. The secondary lock out has to be unlocked- like it is in the photo. When the choke is fully closed, the lock out will prevent the secondaries from opening.

If the secondary shaft or butterflies are stuck shut, the throttle can still feel like it is opening fully, so you need to actually watch to see that the secondary shaft is turning.

Next, the spring setting for the air valve (large secondary butterfly on the top of the carb) has to be set correctly. If you take your finger and press on the air valve to open it, it shouldn't take a lot of pressure, and it should shut easily by itself when you remove your finger.

When the secondary is set correctly, you will not feel a big surge or "kick" when the secondaries open up. You should hear a change in pitch, though.

The secondary unloader/choke pull off (the silver vacuum can on the front passenger side of the carb) holds the secondary air valve shut until the throttle is opened up if it's working correctly. It should be connected to the nearest vacuum port w/a short length of vacuum tubing. Be sure to check it to see that it's retracting when vacuum is applied and is holding that vacuum and not leaking (connect a long piece of vacuum hose to it and pull a vacuum on it w/a vacuum pump or your mouth)- often they are bad and allow the secondary to open too quickly, although this doesn't seem to be your problem.

Also be sure the cam is still in place on the air valve shaft that lifts the secondary metering rod hangar. If it's missing, there will be no secondary action- just a huge bog and/or a lean backfire through the carb.
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Old 08-01-2011, 11:16 AM
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Quote:
Originally Posted by slowboy
Main problem I'm having besides secondary, is I have to pump gas pedal 7 or 8 times before truck will start.
I have the same issue. I have noticed that if I pump the pedal about three times and attempt to start the engine (mine's a '77 Chevy truck), it turns over but doesn't start. Then, if I floor the pedal and start the engine, it comes on quite strong.

I think a few times on the very first try, I pumped the pedal about four times first, then floored it as I started the truck and it came on just fine.
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