Qjet secondary problems
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Joined: Feb 2005
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Qjet secondary problems
I am using my original quadrajet on a brand new crate engine I just put in. I decided to stay with the old carb because it worked so well on the other engine. However, the secondaries are not working on the new engine. It probably has something to do with the fact that I am using a different intake manifold and I blocked something off that isn't supposed to be blocked off.
Does anyone have any ideas what my problem could be? I'm not very good with qjets yet... BTW this is on a '77
Does anyone have any ideas what my problem could be? I'm not very good with qjets yet... BTW this is on a '77
Le Mans Master
Joined: Jul 2005
Posts: 5,752
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From: Austin Texas
I'm guessing your new motor may not have provisions for a choke heater system. Make sure the choke is fully dis-engaging the secondary throttle plate. The choke lock-out is found on the passenger side of the base-plate. 
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did the original choke heater come out of the intake manifold or off of the exhaust manifold? I switched to headers back in july and it ran fine after that without whatever that was on the passenger side ramhorn
Le Mans Master
Joined: Jul 2005
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From: Austin Texas
The original choke system used a steel tube that ran into the intake manifold, picking up heat from the right exhaust manifold. With headers and a different intake manifold, your choke may never open. You may try to convert your carb. to an electric choke, if possible.
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From: At my Bar drinking and wrenching in Lafayette Colorado
Are you sure the secondaries don't work? You can't get the secondaries to open on a Q-Jet by "winging" the throttle in neutral - the engine must be under load.
There are only 2 things that can prevent secondary opening on a Q-Jet:
1. Secondary lockout lever engaged. There is a choke-activatede lock lever on the passenger side right at the secondary throttle shaft. If the choke is not fully open, the lever will prevent the secondaries from opening. Once the choke is wide open, the lever will retract. Be sure the lever is not engaged when the choke is open.
2. Inadequate throttle cable travel. I see this a lot. With the engine off, have someone push the pedal to the floor and verify that the secondary throttle is going wide open (making sure the lockout lever is retracted). If not, adjust your cable geometry.
The secondaries on a Q-Jet are mechanical, so they will open as long as there is no mechanical restriction to their operation.
There are only 2 things that can prevent secondary opening on a Q-Jet:
1. Secondary lockout lever engaged. There is a choke-activatede lock lever on the passenger side right at the secondary throttle shaft. If the choke is not fully open, the lever will prevent the secondaries from opening. Once the choke is wide open, the lever will retract. Be sure the lever is not engaged when the choke is open.
2. Inadequate throttle cable travel. I see this a lot. With the engine off, have someone push the pedal to the floor and verify that the secondary throttle is going wide open (making sure the lockout lever is retracted). If not, adjust your cable geometry.
The secondaries on a Q-Jet are mechanical, so they will open as long as there is no mechanical restriction to their operation.
