Beetle dies when braking

[Jack Nel]

I'm 90% convinced my problem is solved....
Every article I read said not to touch the long screw on the choke plate, but after checking and double checking all other possible causes I decided to turn that screw anyway, and immediately there was a big improvement, no more dying at stop streets, only a little bit of a flat spot now when taking off and when changing gears.....
No rocket science or A-ha moment, but important thing is I can enjoy driving the Beetle again.

[Haans]

Jack,.....sorry boet,..now you sound like a rocket scientist,..........explain this "long screw" a bit more
You've lost me !

Haans

[fig]

I think he's talking about the adjuster screw that rests against the choke steps. The adjustment procedure says do not use this to adjust idle speed. However, before adjusting idle speed, the first step is to ensure this screw just touches the lowest step (ie, engine warm) and then screw it in one and a half turns (IIRC). Then you use the volume control screw to adjust idle speed (assuming idle mixture is correct).

I'm glad you've solved the problem jack. It may be a good idea to repeat the entire idle adjustment process and check idle mixture.

[73type2]

.. and then screw it in one and a half turns ..

Too much. I would screw it in a quarter turn.

[fig]

.. and then screw it in one and a half turns ..

Too much. I would screw it in a quarter turn.

That may be correct. I was going on memory. It must just make contact with the step.

[Jack Nel]

I think he's talking about the adjuster screw that rests against the choke steps. The adjustment procedure says do not use this to adjust idle speed. However, before adjusting idle speed, the first step is to ensure this screw just touches the lowest step (ie, engine warm) and then screw it in one and a half turns (IIRC). Then you use the volume control screw to adjust idle speed (assuming idle mixture is correct).

I'm glad you've solved the problem jack. It may be a good idea to repeat the entire idle adjustment process and check idle mixture.

Correct, I'm talking about the adjuster screw that rests against the choke steps.

[Jack Nel]

As you say, correct adjustment procedure says to adjust the screw until it just touches the lowest step (ie, engine warm) and then screw it in half turn. Then you use the volume control screw to adjust idle speed.

However, I turned mine about 2 turns in already, but as Fig suggested, I will repeat the entire idle adjustment process again.

Thanks for all the advice given.

[73type2]

Then you use the volume control screw to adjust idle speed.

Sorry to be picky, but I think you mean the Bypass screw (big one) to adjust the idle speed. Volume control screw (small one) is used to set the mixture. Here is one of many guides to be found on the internet:

Setting the 34PICT/3 carburetor

Engine warmed up, but switched off. The screw on the throttle arm, which faces to the rear of the car is called the Fast Idle Adjuster. This works with the choke to give a smooth idle on a cold engine. Unscrew the Fast Idle Adjuster (sits on the stepped cam), until it is clear of the stepped cam. Now screw it in until it JUST touches the very bottom of the stepped cam - NOT on any of the steps themselves. Now screw it in another 1/4 turn - no more. This sets the throttle butterfly open the required .004 inch, so you can use the Bypass screw (read on) to set the idle speed correctly. Now leave the Fast Idle Adjuster screw alone.

Turn the Volume Control Screw (smaller screw in the side of the carby) in until it bottoms. GENTLY please - you don't want to open up the hole. Now unscrew it 2.5 turns. This is the starting setting.

Start the engine and use the Bypass Screw (larger screw in the side of the carby) to set the idle at 850rpm (fast idle if you don't have a tacho). For a semi-auto car, use 900rpm.

4. Go back to the Volume Screw and adjust it slowly for the fastest idle. It should not be much outside the range of 2-3 turns (½ turn in/out from the 2.5 basic setting). Then turn it very slowly IN until the revs drop by about 30rpm. If you don't have a tach, listen until you can just hear the revs start to drop, maybe as little as 1/8th turn.

Now use the Bypass screw again to reset the idle speed to 850 rpm (900 for the semi-autos).

That's it - you're done. If it still doesn't run right, something is worn or broken. Check the usual - air leaks, trash in carb, trash in fuel lines, coil dying, bad wires, bad etc.

[Jack Nel]

Then you use the volume control screw to adjust idle speed.

Sorry to be picky, but I think you mean the Bypass screw (big one) to adjust the idle speed. Volume control screw (small one) is used to set the mixture. Here is one of many guides to be found on the internet:

Setting the 34PICT/3 carburetor

Engine warmed up, but switched off. The screw on the throttle arm, which faces to the rear of the car is called the Fast Idle Adjuster. This works with the choke to give a smooth idle on a cold engine. Unscrew the Fast Idle Adjuster (sits on the stepped cam), until it is clear of the stepped cam. Now screw it in until it JUST touches the very bottom of the stepped cam - NOT on any of the steps themselves. Now screw it in another 1/4 turn - no more. This sets the throttle butterfly open the required .004 inch, so you can use the Bypass screw (read on) to set the idle speed correctly. Now leave the Fast Idle Adjuster screw alone.

Turn the Volume Control Screw (smaller screw in the side of the carby) in until it bottoms. GENTLY please - you don't want to open up the hole. Now unscrew it 2.5 turns. This is the starting setting.

Start the engine and use the Bypass Screw (larger screw in the side of the carby) to set the idle at 850rpm (fast idle if you don't have a tacho). For a semi-auto car, use 900rpm.

4. Go back to the Volume Screw and adjust it slowly for the fastest idle. It should not be much outside the range of 2-3 turns (½ turn in/out from the 2.5 basic setting). Then turn it very slowly IN until the revs drop by about 30rpm. If you don't have a tach, listen until you can just hear the revs start to drop, maybe as little as 1/8th turn.

Now use the Bypass screw again to reset the idle speed to 850 rpm (900 for the semi-autos).

That's it - you're done. If it still doesn't run right, something is worn or broken. Check the usual - air leaks, trash in carb, trash in fuel lines, coil dying, bad wires, bad etc.

All of the above is correct and the way I understand it, thanks, just getting a bit mixed up with the names of the different screws

[fig]

Something to keep in mind is that the basic setting of 2.5 turns out on the volume control screw applies at sea level. I've found at reef altitude it's about 1.5 turns.

Since most of us don't own an exhaust gas analyser, I find the best tests of whether your idle mixture is correct are:
1. Use your nose. You can smell when it gets too rich.
2. Feel the exhaust gas out of the pipe; too lean makes it very hot.

[Haans]

Now I am on the same page !

All te specs to adjust is to me,..... the starting point,....every engine will be tweaked around it

Check for vac leaks,...can be bliksem to tune with it

Thanks

Haans

[Terry Phillips]

Have you checked the throttle shaft for wear in case no one mentioned if. my 2c

[73type2]

Another check for leaks: Theoretically, if there are no leaks the engine should die when the volume control screw is fully seated.