Adjusting the carb choke

[71superAS]

Hello all,

I live in upstate New York and it was a balmy 6F yesterday. Naturally, my little Beetle's carb could not handle this when I gave the gas any strong amount and would stall out. .

I currently have a 34-PICT-3 carb, is it possible to adjust the choke on this model? If so, how would I go about this?

Thanks for listening,
Patrick

[Marc]

http://www.vw-resource.com/choke2.html

The time to do this is when the engine's stone-cold; if you adjust the choke plate to fully-closed when it's warm, it'll be too aggressive when things cool down.

...there should be no reason for you to dismantle anything (beyond removing the aircleaner and loosening the three screws mentioned) - unless the choke element is removed there's little chance of the bimetal spring becoming "unhooked".

[71superAS]

Are you thinking process 2 then?

[Marc]

Probably all you'll need to do. If things are binding or you need to remove the heating element for some other good reason (to replace it, or clean up corrosion interfering with a good ground for example) follow the other procedures. Most carbs have three little plastic/nylon spacer tubes on the screws that secure the retaining ring, be careful not to lose them.

[Jim Ed]

When the engine has warmed up, shouldn't the choke be straight up and down?

[Marc]

When the choke heating element is hot it should be. That may or may not correlate precisely with actual engine temperature, but it usually takes no more than 3 minutes with the ignition switched on for the choke plate to get to full-vertical.

[71superAS]

Yes, it now gives me no issue starting it up since tweaking it. One thing I do notice though is that it wants to stall when I let off the gas too long. Given that it is an autostick and I have no clutch to press down, do I have to pop it out of gear anytime I want to idle? Or is that a further choke-related issue?

[Marc]

I wouldn't expect to solve that with choke adjustment, but you should be able to by tweaking the idle mixture and/or curb idle speed slightly. If the carb throttle shaft is worn enough to make it impossible to find a stable idle speed, the best you'll manage will be the highest idle speed (up to, say, 900RPM) that doesn't cause a disconcerting lurch when shifting into Reverse.

[71superAS]

Ha, I actually do have that lurch now, so I will have to look at replacing that part. I was kind of eyeing the dual carb setup from aircooled.net

[Marc]

Autostick carburetors have an extra vacuum port which connects to the clutch control solenoid. Clutch reengagement speed is modulated to limit slippage under heavy load, and reduce harshness when driving gently. Does the carburetor now on the car have that vacuum line? No dual-carb setup, and only a few stock-replacement carburetors, will have provision for it. With a "normal" control valve adjustment and no vacuum hose the clutch will reengage too slowly under load, causing overheating and excess wear. The control valve may be adjusted to compensate, but that causes overly aggressive engagement under gentle/average driving.
Autosticks also have specific distributors with an advance curve tailored to work in concert with the torque converter stall speed. If you have a "4-speed" distributor it's difficult to tune for optimum driveability. All stock-replacement carburetors have provision for the vacuum advance signal, but as a rule dual-carb setups do not.
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