VW 105-1, 30 Pict-1 Carburetor – The Choke Processes, Part 2

In Part I, we examined the elements of the Choke Processes. 

In this article, we want to adjust the Heating Element so that the Choke Plate will respond properly as the engine is working to arrive at operational temperature.

The time to adjust the Heating Element is when the engine is cold and the Key is NOT in the Ignition. 

Remove the Air Breather for ease of access to the Carburetor and so that you can see the Choke Plate inside the throat of the Carburetor.

We need the Idle Cam to be free during the adjustment process.  You can remove the Accelerator Lever (or Arm) Return Spring, for the moment, to disable the Accelerator Lever.

Slightly loosen the Three Heating Element Screws at the Retaining Bezel.   This will allow us to move the Heating Element clockwise or counter-clockwise.

If we turn the Heating Element counter-clockwise, the Bi-Metal Spring Hook (inside the Choke Heater Housing) will catch the Upper Arm of the Choke Plate Shaft, forcing the Plate to close.

If we turn the Heating Element clock-wise, we release pressure upon the Upper Arm of the Choke Plate Shaft, allowing the Choke Plate to open.

Perform this exercise while watching the Choke Plate.  You soon will have a feel for this adjustment.  Not every Carburetor will adjust the same due to the nuances of mass-produced Heating Elements and Carburetors and old Carburetors, etc.

Our objective is to put enough pressure upon the Choke Plate so that it comes almost to a fully closed position.  But not quite.  If we force the Choke Plate fully closed, it will take the Heating Element too long to heat in order to relax the Bi-metal Spring.  When the Choke Plate is closed hard, the Fuel Mixture remains charged with gasoline, but with insufficient air, so that the engine begins to struggle for a less enriched mixture as it begins to attain operating temperature.  (Even more so if this occurs during warm or hot weather when it should not take as long for the Heating Element to heat the Bi-metal Spring.)

David Brown tells us:  “I feel that in most cases the Choke is set too “rich”, that is, closed too far to begin with. When setting the Choke in real cold weather, I set it to lightly closed.   When setting it in warmer weather, I set it to close only to about 3/8″ or so from fully closed. VWs don’t really need much choke.”

David continues—“ The Choke setting affects not only the cold starting but the length of time the Choke is active. If it’s off too soon….before the engine is ready to idle without the choke’s help….it’ll stall at the first stop sign. If it’s on too long, it will waste gasoline, carbon up the spark plugs and may even run poorly.”

Once you believe that you have the Heating Element turned so that the Choke Plate is properly tensioned, hold the Heating Element so that it does not slip.  Gently tighten the Three Screws at the Bezel.  Do not over-tighten and strip the threads!  Once the Screws are tightened, test the Choke Plate.

To do this, flip the Idle Cam.  The Choke Plate will respond and return to rest as you have set it—at a loose closure.  If you see that the Plate is too loose or too tight, repeat the process.  Once you have become familiar with the process, you will find it easier the next time.

Another general method for setting the Choke is to use the three “Pips” (see the photo).

Align the groove on the Choke Heater with the Center Pip.  This is not exacting and is to be used only as a reference point, I feel.

David Brown says, again:  “The “pips” on the Choke Housing and the line on the Choke Element make for a pretty close setting. If your choke is needing a setting way off of those pips, there is something wrong.”  (could be the wrong Choke Heater Element?)

(Update)–David Brown writes:

The Factory Service Manual, Section  K , Fuel Systems, SPECIFIES that the choke be assembled on the center pip. There are NO OTHER mentions of adjusting the choke in any other way!!  So, there you have it right from the Factory.  I still would adjust them to suit the weather, but only slightly. (No mention of the purpose of the other Pips.)”

Reengage the Accelerator Lever Return Spring.  Replace the Air Breather. 

Now go and drive your Beetle and enjoy the feel of the road!

Notes: 

1.  Thank you, David Brown, as always, for your great contributions.

2.  Thanks, also, to Barry Blythe, a Texas VW Engine Builder of many years—for his advice concerning the Choke Plate Settings.

3.  Thanks to our daughter, Janeva Sulman for her videography abilities!

The Finishing Touches for Your Vintage Volkswagen™

Posted by Jay Salser

My wife, Neva, and I have been driving and working on VWs since 1976. In fact, we raised our family in these cars. Now, we are retired and enjoy VWs as a hobby. The ’67 Beetle always has been our favorite year. We own a '67 Beetle and a '68 Karmann Ghia.

  1. Brother, JK is back; with video! Always such helpful information for the ’67 Beetle community.

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  2. This is such a well written article that it “chokes” me up.

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    1. Mike–Your comment is so “punny”–it is a gasser! jay

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      1. I’m still laughing….

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  3. I’m “choked” up as well, Mike! When are you going to start on your next ’67 Beetle?!

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  4. Great write up in very layman’s terms. A couple of other things that people need to realize when adjusting their chokes as well. Does their engine have a working thermostat and flaps in place? Are their heat risers clear of carbon? Are they running the correct stock muffler that supplies ample hot exhaust flow through the heat riser to the carb manifold? Aftermarket mufflers don’t flow 10% of what a stock one does.

    1) These electric chokes were “timed” to open in so many minutes as the engine reaches operating temperature. The choke “expects” that the engine has the thermostat and flaps in place to help the engine reach operating temperature at the same point as the choke is fully open. As we all know, many people are NOT running the thermostat and flaps and can’t understand why the choke doesn’t appear to adjust correctly. Meaning, the engine still has cold engine symptoms when the choke is fully opened by the electric element.
    2) The carb manifold heat risers need to be clear of carbon so the hot exhaust warms it up so the fuel atomizes easily down those long intake runners. Owners also need to run a stock muffler that supplies the correct amount of exhaust to the heat risers.
    3) Having the warm air inlet working on the oil bath via the stove pipe also helps cold engine symptoms as well. From 1968, VW had a system in place via a “bowden” cable that connected to an extra arm on the flaps. From that point forward, VW had a warm air inlet on the oil baths and air filters. These warmed up the intake air going into the carbs. In 1967, the oil bath got hot inlet air to the carb from the warm air pipes pointed under the heads.

    Over the decades, many VW’s had lazy mechanics or owners who removed the thermostat and flaps, unhooked the warm air inlet to the oil bath and installed a header style muffler. They then wondered why their VW runs terrible for the first 5-10 minutes on a cold morning.

    I’ve reinstalled all these missing pieces, cleared clogged heat risers out and insured the warm air to the carb system worked on the oil bath. It’s a night and day difference when these parts are installed on a cold winter morning. You simply depress the accelerator pedal to engage the choke, start the VW and drive off with no cold engine symptoms. :)

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    1. Hello, William…thank you for explaining the process of heating the engine/fuel-air mixture. The process is complex. Not only is it a “heating process” but it is a “cooling process”. EX: with the removal of the thermostatic system, the engine cannot properly cool itself. Again–thank you for noting the German engineering which went into the heating/cooling process of these wonderful engines! jay

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    2. Great info, William.

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  5. Author’s Correction: In the video, I say that the “30 Pict-1, VW 105-1 carburetor is the one which came on all 1967 Volkswagens”. I should have said that this carburetor came ONLY on 1967 Deluxe BEETLES coming directly from Wolfsburg to the USA. jay salser

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  6. Our son, Kevin, who grew up with VWs, adds this comment: “The “springiness” of the bi-metal spring allows the choke plate to open more under high vacuum conditions. So when the engine is running at higher speeds, the force of the air moving through the carburetor will hold the choke plate open more than normal, even if the engine is still cold. That’s why it needs to be a spring that is changing tension, as opposed to just a fixed movement. It would be interesting to hook a battery to the bi-metal spring in your “demo” carburetor to see how long it takes for the spring tension to change as it heats.” ( Author’s note here: There also is a vacuum assist to the Choke Plate Shaft which I did not address since it does not concern the setting of the Choke Plate. jay)

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  7. Smart German engineering of old.

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  8. Very informative video. Simple and right to the point! Thank you !!!

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  9. I tried adjusting mine today only to find the choke plate sticks when fully shut moving it by hand,so it has been sticking on full choke and all my plugs keep getting sorted up.Has anyone any idea how I can free it up so it’s as free as the one on you tube.zi am in uk

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    1. Hello, Brian…Thank you for commenting! This was going to be the title of my next article–how to free the stuck choke plate shaft. Here’s a method for a temporary fix. Using a solvent (even WD.40 will work), spray some behind the Idle Cam while working the Cam back and forth. Gas Resins tend to collect in the shaft orifice. Remove the Air Breather so that you can spray just a bit where the shaft enters the Carburetor Casting on the inside–on both the Idle Cam side and the Choke Heater side. Keep working the Idle Cam. I have done this operation a number of times with success. What’s happening is that the solvent is dissolving the Resins and freeing
      the Choke Plate Shaft. Ultimately, removal of the Carburetor’s top and a good soaking in a Carburetor Cleaning Solution may be necessary. Sometimes we just need to “bite the bullet” and do that. jay

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  10. Thanks that’s a relief ,I was feeling pretty fed up and worried when I discovered it yesterday,I will have a go when we get back from holiday in Israel next week. This site is so useful.

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    1. Brian–It has been a while since I cleaned the top of my ’67 Beetle’s carb. I notice, especially now that we have cooler weather, that the choke plate is sticking a bit. I may use the solvent–then a drop of a light oil to lubricate the shaft. I find that most of our daily “problems” are easily solved once we sit to examine and follow the train of “active ingredients”. LOL jay

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  11. Hi Jay –
    GREAT article and video
    Thank You and great to see your back at it !!!
    Clyde

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    1. Good to hear from you, Clyde! Thank you for your comment! I don’t have much endurance but do what I can. It takes me longer to do anything since the surgery. I tell everyone that since the surgery, when I go to a car show, they put me into the “modified class”–since I am missing some original parts! LOL. Tell your wife hello from me! jay

      Reply

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