Thermoquad Linkage Problem Question

[gerahead]

My project is a 71 Dart and I am swapping in a 340 that is 72 or 73 vintage. I am wrapping up the engine redo and I am in the process of going through the carb. The engine had been partially disassembled when I got the car and this carb hasn't been on a running engine for as long as I've had it. My question is . . . . as I was taking it apart (I am no Carter carb expert) I noticed that a portion of the linkage on the rear driver side of the car had been wired together. I have no idea how this linkage should be connected or even if I am missing some parts. The first pic is a side view of the carb, the second a closeup of the linkage in question and finally the same pic as number 2 with the problem area highlighted. Is there someone out there with a similar set up that can post a pic from their car showing the correct connections? Thanks in advance!

Jim

 

[Vaanth]

My project is a 71 Dart and I am swapping in a 340 that is 72 or 73 vintage. I am wrapping up the engine redo and I am in the process of going through the carb. The engine had been partially disassembled when I got the car and this carb hasn't been on a running engine for as long as I've had it. My question is . . . . as I was taking it apart (I am no Carter carb expert) I noticed that a portion of the linkage on the rear driver side of the car had been wired together. I have no idea how this linkage should be connected or even if I am missing some parts. The first pic is a side view of the carb, the second a closeup of the linkage in question and finally the same pic as number 2 with the problem area highlighted. Is there someone out there with a similar set up that can post a pic from their car showing the correct connections? Thanks in advance!

Jim

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The wired lever is part of the secondary lockout setup. The front of the lever has been broken off and it has been wired to allow secondary operation, but without the lockout function.

The following image shows an intact setup:

The secondary lockout prevents the secondaries from opening until the choke is fully, or near fully open. Following is another image of the setup:

Your lever front curved inward piece is broken off, so the pickup piece on the primary lever has nothing to grab to open the secondary plates. The secondaries will be allowed to open when the choke is not yet fully open, but the carburetor will function normally otherwise. If opened when cold, the secondary transition likely will not be clean or smooth and may bog or stall the engine.

The following image shows the lockout adjustment with an intact lever:

 

[gerahead]

Jeez, more crap I have to figure out how to work around. Thanks for your help, it is greatly appreciated!

Jim

 

[townsend]

This is a direct quote from Mopar guru Richard Ehrenberg.
One drive ability feature on OEM Thermoquad's may get you in trouble for any type of racing usage: the secondary lockout.
This gadget, built into the throttle - linkage, prevents the secondaries from opening if the choke is on, even partially.
For racing use,of course lack of open secondaries when you need them could be disastrous.
The fix is simple: disable the lockout by tying the levers together with a small length of bailing wire.

As Vannth alluded to, this can cause problems on a non - race vehicle.

 

[gerahead]

Thanks Townsend, I have zero experience with the thermoquad and had no clue what was being done with this tweak. Having an inop lockout won't be an issue for me, none of my high performance cars have functioning chokes. I can live with it until I find either a new carb or a complete base plate.

Jim