Whats this on my Carb?

[fisch]

What is this box with wires on my stock 521 L16 carb? I have a manual choke, and the pictures I've looked at in my books aren't showing this thing. (Or am I missing it?)

 

Sorry for not knowing this, but this is the second car I've ever owned with a carb.

 

I am looking into a weber upgrade and if this has an electric hook up already should I be looking at DGEV's?

 

I do notice when I pull the choke knob the barel doesn't close all the way. But I guess that could be an unrelated sticky cable.

 

Thanks for looking. I know I will feel like a moron for not knowing the answer!

 

[datzenmike]

Looks like the throttle position switch which signals the emission control system if the carb is at full throttle OR closed at idle. Combined with the third (or fourth) gear switch in the tranny, it turns on or off the retard points in the dual points distributor.

 

There were several set ups for this but very basically it kept the retard set of points in operation when in lower gears but not high gear at highway speeds. This was to reduce emissions.

[fisch]

Thanks Mike., will there be any issues when I put on a carb w/o this? Can I just tie the two wires together to bypass and remove?

[datzenmike]

I would just leave the wires off and tape them up. Maybe disconnect the retard points so you are at the proper full advance all the time. Higher emissions, but better performance I would think. The first set are set for about 10 degrees advance, the second set for 10 less or 0 advance when in operation.

 

At low to moderate speeds and throttle, there is high manifold vacuum. The distributor advance moves ahead to give this weak, poorly compressed mixture more time to burn. There two problems with this. The longer burn time results in higher combustion temperatures at peak pressure and thus more time for oxygen and nitrogen to combine into nitrogen oxides (NOx). At the same time the piston is further down the cylinder and there is a larger quench area or cooling effect, at the time of ignition. This cooler fuel/air will not burn as readily and results in more unburned hydrocarbons. Retarding the ignition thus (at low speeds) helps burn the fuel better and shorted the time NOx is produced.

 

Later models put a restriction in the vacuum line to prevent sudden advance in ignition timing. Others had a temp switch that disconnected this system on a warmed engine.

[fisch]

I would just leave the wires off and tape them up. Maybe disconnect the retard points so you are at the proper full advance all the time.

 

I am about to put on my weber and am refreshing my memory with this thread.

Mike (or anyone) how do I disconnect the retard points on the dist? Where do i find them, and what do they look like?

 

I have an electric dist to put in, but I kinda want to do one thing at at time and make sure it works before I do the next thing.

 

Rock on.

[datzenmike]

I am about to put on my weber and am refreshing my memory with this thread.

Mike (or anyone) how do I disconnect the retard points on the dist? Where do i find them, and what do they look like?

 

I have an electric dist to put in, but I kinda want to do one thing at at time and make sure it works before I do the next thing.

 

Rock on.

 

The easiest way to disable it, is to disconnect the wires to the carb switch. This will prevent the relay from selecting the retard points in the distributor. Or of the two wires going to the connector on the distributor, disconnect the Blue/Yellow one.

[fisch]

You totally Rock Mike. Thanks man!