VW 105-1, 30 Pict-1 Carburetor – Part III – Stuck Choke Plate Shaft

With colder weather, especially, the Chokes on our 1967 Beetles with the 30 Pict-1 Carburetors play an even more important part in the starting of the car.  We want the Choke Plate to be closed so that there will be a more rich fuel mixture to kick-start the Engine and get it to running temperature.

Given that the Electric Choke Element is in working condition—we want to get into our cars, press the Accelerator Pedal once and let up.  This allows the Spring in the Electric Choke Element to snap the Choke Plate closed.  Although we can’t see this happening while the Air Breather is on the Carburetor, we CAN see that this is happening by looking at the Idle Cam position. 

When we step on the Accelerator Pedal, the Accelerator Lever is pulled back, allowing the Idle Cam to move freely.  Now, the Idle Cam snaps to its highest position.  The Accelerator Idle Screw is resting, now, on the highest Step on the Cam.

The Engine is racing.  But, this is good!  It is running at higher RPMs, sucking in that gasoline rich fuel mixture in order to bring the Engine to running temperature.

But, we don’t want this to continue on and on and on.  As the Choke Heater Element becomes hotter, it begins to release tension on the Bi-metal Spring, allowing the Choke Plate to slowly open.

The vibration of the running engine, coupled with the foot action at the Accelerator Pedal, allows the Idle Cam to slip to a lower position.   The Choke Plate opens more and more until it is pointing almost straight up, allowing more and more air to mix with the fuel.

This process continues until, eventually, the Idle Screw is resting on a low Cam Step and the Engine is idling at a lower speed.  The Electric Choke has done its job well.

But what happens when the Engine continues to run and run and run at high speed and the Idle Cam doesn’t move.  And—nothing that we do seems to help it to move—apart from manually moving it.  Something is not right.

It is possible, also, that the Choke Plate Shaft can stick at Low Idle or anywhere along the Idle scale.

As our Engines operate, Fuel Residue builds on the Choke Plate Shaft.  Eventually this gummy residue can cause the Shaft to stick.  And, even though the Choke Spring has released tension on the Plate, the Plate cannot move to the open position.

One method which may help is to spray Carburetor Cleaner directly onto the Shaft behind the Idle Cam.  Often this is sufficient to loosen and wash-away residue.   Aerosol Carburetor Cleaner sprays can be obtained at any local parts store, with plenty of choices available.

Remove the Air Breather.  Spray liberally every where the Choke Plate Shaft and the Carburetor Body intersect.  Move the Idle Cam as you spray to see if the spray is being effective.

This may not be sufficient to completely remove residue and allow free movement to the Choke Plate Shaft.

Note:  Restriction of the Idle Cam also may be caused when the Limiter Pin becomes jammed in the curved slot of the Idle Cam.   It is possible that the Pin may have become bent, perhaps just from years of use.  The original Pins were brass.  The Pin can be  straightened or a substitute steel roll pin can be installed.  This may involve drilling to enlarge the Pin’s anchoring hole.  A new Pin should be sized carefully so that it will fit the slot as the Idle Cam pivots and not cause binding because it is too large in diameter.  I used to make my own brass Pins when one would be lost or bent or broken.

Other causes of binding of the Idle Cam can include corrosion or dirt in the Choke Plate Shaft’s Bore.

If all efforts of spraying a solvent at the Choke Plate Shaft fail to loosen the Shaft and allow it to rotate freely, a thorough cleaning is warranted.  This requires removal of the top of the Carburetor

You don’t have to remove the Carburetor from the engine, but it makes the work easier, in my opinion.  Once the Fuel Hose has been removed, and the Accelerator Cable, the Accelerator Lever Return Spring and the electric wire to the Choke Heater have been removed, use a 13mm end wrench to loosen and remove the two securing nuts at the Manifold.

With the Carburetor in hand……..

Remove the Electric Choke Heater parts. 

Remove the Choke Vacuum parts.

Using a 10mm closed end wrench, remove the nut securing the Choke Plate Lever and the Idle Cam to the Choke Plate Shaft.  See the photo below which reveals the parts in their order of removal/installation.

Review the Brass Bushing.  If it appears to be less than smooth where the Idle Cam fits over it, use some very fine wet-dry abrasive paper to polish it.  I use 1000 grit, or finer, commonly. Use the same polishing technique on the end of the Choke Plate Shaft where the Bushing fits.

Remove the 5 retaining screws which secure the top of the Carburetor to the bottom half (Throttle Body).  Carefully lift the top, taking care not to damage the gasket between the top and bottom halves.   It can be reused if it is undamaged in this process.

Remove the Float Valve—14mm end wrench.

Note:  Do NOT attempt to remove the two Retaining Screws which hold the Choke Plate to the Shaft.   These Screws have been installed at the factory so that they will not loosen and be sucked into the combustion chambers where they can cause major damage.

Photograph #64 shows a Choke Plate and Shaft (for comparison) removed from an identical Carburetor. 

Cleaning can be accomplished by putting the Carburetor top into a can of Carburetor Cleaning Solution.  A half day usually is enough time for the cleaning to take place.

*All cleaners should be used outdoors where there is plenty of ventilation.  Use protective gloves.

After using a Carburetor Soaking Solution, follow the directions on the container for removing residual Cleaning Solution.

If you use an aerosol spray, spray the Choke Shaft liberally, working the Shaft as you spray. 

Once cleaned, the Shaft should turn freely—with NO resistance. 

The Shaft and its Bore can be lubricated with a few drops of anti-corrosion oil.  Work the Shaft several times to ensure proper dispersal of the lubricant.

While you have the top half of the Carburetor removed, clean all outer surfaces well.

Reassemble in reverse order. 

Start with the  Choke Plate Shaft fittings at the Idle Cam Side.  Be sure that the Nylon Washer on the Choke Plate Shaft is fitted over the Brass Bushing and not pinched between it and the body of the Carburetor Top.

Once these parts have been reassembled, check movement.  Is the Choke Shaft turning freely?  Is the Idle Cam moving freely?  If not, determine why not before continuing reassembly.  This is the condition which we wanted to remedy when we began this exercise.

When you are satisfied with your cleaning efforts, reassemble the rest of the Top’s parts.

Then reattach the Top to the Throttle Body (bottom half of the Carburetor).  Do not over-tighten the screws!

Bolt the Carburetor onto the manifold and reinstall the Accelerator Cable.  Properly adjust the Choke Heater Setting, and reinstall the Electric Wire to the Choke Heater.

If the work has been done properly and there is no physical reason for the Choke Plate not to function properly, you should have plenty of trouble free driving for many months or years to come.

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. As always, great article, JK!

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  2. Thanks SO much ,Jay

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    1. Hello, Frank…Thank YOU for reading. This problem is one which I have worked with over the years with my own VWs. Since now I do not drive our two VWs much, I think t hat the problem surfaces more. It all goes to show that we need to drive (and enjoy) our cars
      more than just to shows or meetings. jay

      Reply

  3. A great supplement to my Idiot’s Guide. Jay. You are indispensable.

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  4. Hello, Fritz—Thank you for reading and commenting. I hope that the Winter has not been too hard on you and your wife. Keep driving your ’67 Beetle! jay

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  5. Mine drive me nuts because it stalls sometimes (Ok a lot) when coming to a stop.

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    1. Hello, David—Thanks for reading and commenting. Read the Part I and Part II. Your stalling could be one of several issues. See if the other carburetor articles shed any light upon your situation. You might also read the article called “the fuel system”. Go through the fuel system front to back to rule out every part of the system as being the culprit. If yours is a stock VW Solex carburetor which never has been refurbished, and you narrow the problem to the carburetor itself, perhaps it is time for that to take place. If you need help, seek a qualified vintage VW repair shop for help. I wish that I could be more specific but the disadvantage is being at long-distance. jay

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  6. Great article Jay! Thank you! Weather is warming up here in my part of the world. Spring is in the air.

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    1. Hello, Guy…Thank you for your comments! While we here in North Central Texas see occasional Spring-like indications–I have yet to see the House Sparrows building nests. Usually by this time, they are. I expect more cold weather. Keep enjoying your wonderful Black ’67 Beetle! jay

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  7. I have to confess, I own a 63 with what appears to be the original engine. According the the engine number it was built in October of 1062, the same month as the car. It had a Chinese carb on it when I bought it and I thought that was blasphemy. I found a Solex online, but one for a larger engine. I rebuild the carb (a first for me) down to the ball bearings. I believe you and your friend helped in in selecting the right jets for it. It runs great when moving, it is just coming to a red light or stop sign when it sometimes just dies rolling to a stop. I would like to thank you for your help that already gave me.

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    1. Good morning, David–I have been thinking of your situation all night and again this morning. While it IS possible that the Idle Screw could be turned in a bit to increase idle speed, I hesitate to “fix” a problem by simply making the carburetor idle faster. Check idle speed to see if this is a problem, or not. Does the engine die only for the first few miles–then is okay at stop signs after that? jay

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  8. Thanks for responding Jay. You did not have to think about it that much, but thank you. Honestly, your page has been a wealth of information for me even though I am in an older beetle. You could have easily told me to go away since I do not drive a 67, but you didn’t. It does seem to do it when it warms up more. It does in intermittently it seem, but I have to use the e brake to hold he car while I keep my foot on the gas to keep the idle up at a stop

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    1. David—I have sent an Off-Site response so that we can discuss your situation more easily. jay

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    2. David…Eric Shoemaker’s Motto is “We’re Here For You!” We’re not here to turn people away or to ignore people and their cars. jay

      Reply

  9. Double thumbs up Jay..

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    1. Thank you, Jeffrey! Thank you for being a regular Reader of 1967beetle.com! Eric and Amanda Shoemaker put a LOT effort into the 1967 Beetle Community for all of us out here. Reader support is so important! jay

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      1. Yes, this site is for all globally! Created to help others. We do it because we care.

        Reply

  10. Thanks Jay!!

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    1. Hi, Todd! How’s that ’67 Standard doing these days. I have forwarded Your Story to many who have questions about the Standards. There are lots of answers to questions in your article. It is a joy to just click-and-send your article. jay

      Reply

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