Carb Adjustment

[rollin900]

I have a solex stock carb. there are 2 screw on the left side, a big one and a small one. does anyone know which one does what?

TIA

Nick

[Marc]

The best step-by-step I've seen published on the 'net is at http://www.geocities.com/aussiebug1970/ ...but I can't seem to get the page to load lately.
This is better than nothing:
http://www.w-p-c.com/buggy34-3adjust.htm
If your stock distributor has been replaced with the ubiquitous 0 231 178 009 centrifugal-advance-only unit things can get a little stickier, but it's still doable.

[alsehendo]

1. Connect tachometer and oil temp gauge and start engine.
2. Check oil temp is between 122 -158 F ,and shut down engine.
3. Check that choke is open fully.
4. Disconnect the accelerator cable from the carb.
5. Turn idle screw out until it is no longer touching fast idle cam.
6. Turn idle screw in till it just touches fast idle cam.
7. Carefully turn volume control screw in till it stops, then turn out 2 1/2 To 3 turns. SMALL ONE
8. Start engine, make sure that choke is open again and reinstall air cleaner.
9. Set idle speed at 900RPM by the bypass screw. LARGE ONE
10. Turn out volume screw to highest idle speed and then turn back in till RPM drops by 20-30 RPM. SMALL ONE AGAIN
11. Turn the bypass screw till the idle is correct at 750-900RPM. LARGE ONE AGAIN
12. Reconnect the accelerator cable.

Reference: (Barb and Eric. http://www.type2.com/)

[germansupplyscott]

6. Turn idle screw in till it just touches fast idle cam.

i think you sould have another step:

7. Turn idle screw further one-half turn.

and so forth.

[rollin900]

ok....the flap in the carb is not moving, neither does the fast idle cam...not by themselves. I have to adjust it if i want it to move.

what controls this and how can i fix it and what would it cost?

[Bob Ingman]

Nick the choke is adjustable. With the key OFF and the engine coldloosen the three little screws on the choke element enough to be able to rotate the inner section your wire goes to. Turn that portion til the choke plate in the top of the carb just barely closes fully. Lock the three screws again. Be sure the wire from coil + side goes to that plate. Turn on key and observe the choke opening in a period of about three minutes.
At least thats how things are supposed to work. If yours does not do so let us know. Cheers. Bob Ingman

[rollin900]

ok....I adjustested the flap....it open when warm. Like 3-4 minutes. Then i start the car. To start it, i have to hlld the flap closed and give it gas. then when i let go of the flap and the gas, it will run for like ten seconds and then start to sputter out. If i am quick enough and hold the flap shut, it will come back to life.....until i release it 10 seconds later. What is causing this? Second question.... What does the bypass screw bypass....what is it used for. what setting should i have it at when try to adjust it. also....when adjusting the fast idle screw....should i adjust it when the stairthingy is pointing up or out? thanks for any input.

[CapnDavy]

OK, I'm up to speed on the textbook carb adjustment procedure... but I still can't obtain a consistent idle.
The engine idles fast but when I use the gears to brake the car (lots of air going thru carb with not much fuel) and finally brake to a stop at the intersection the engine quits. I start it up and it goes back into it's "fast" idle configuration. I must tap the accelerator to get it back to idling smoothly again.

When I get to adjusting the bypass screw (large one) I can close it down with rpm decreasing until about 800 rpm. It is not steady and fluctuates quite a bit +/- 50 rpm. To get a smooth idle I must set about 1000 rpm.

The volume screw doesn't seem to have much effect. I can turn it in until the engine quits, the rpm doesn't decrease gradually as I turn, it just quits. Turning it out from the initial 2 1/2 position doesn't seem to increase the rpm any.

Any thoughts?
Could you describe the function of the volume and bypass screws? What volume is being adjusted? What is being bypassed? And what is doing the bypassing: fuel, air?

[MedicTed]

6. Turn idle screw in till it just touches fast idle cam.

i think you sould have another step:

7. Turn idle screw further one-half turn.

and so forth.

The screw adjustment on the throttle arm is NOT for idle adjustment. The idle speed is set with the bypass valve.