Until the point I can convert back to FI, as discussed here , I need to get my car runnig better.

I have a 72 1.7 with dual weber 34 ict and lately it has not been running well. The car is sputtering at times, surging, and bogging (loss of power) when under load - heavy acceleration or uphill.

Where do I start? Anyone have a step by step guild?

I would be the first to say I am not familar with these carbs.

Thanks

Trevor

QUOTE

Anyone have a step by step guild?

we represent....the lollipop guild..the lollipop guild

not useful to this topic, but serves as a

b

I am the worlds best speller

hey it's all in fun... i cnt spl eifer....buts ima from kentucky.

b

First you need a syncrometer, they have been on ebay for $40 or so. My '73 has dellorto 40's but this may help. Set the mixture control 3 1/2 turns from bottom. This will get motor running and provide a uniform starting point. Check carb idle speed screws, make sure they are in closed position. If not adjust vertical throttle control rods on linkage until both are in closed position. Warm up car. When warm place meter on carb. If using unisyn (ball type) you want to get ball in center of tube. Using a synchrometer you will want dial to be at "5" or a little bit higher. Adjust idle speed screw until ball is centered or showing around 5. When one side is done move meter to other side and repeat. Check first side again as the idle may change when adjusting second side. When both sides are same put guage away.

Now find the mixture control screws. It does not matter which you start with as you must do all four. Begin closing mixture screw (clockwise) until engine starts to misfire from lack of fuel. Very slowly rotate back (counterclockwise) until cylinder picks up proper fuel flow and starts firing. Repeat procedure with other three mixture control screws. When engine is running smooth without popping or surging turn each screw out 1/4 turn more. Remember to adjust only one screw at a time.

There is another way to adjust (more accuratly)but I do not have a four column vacume guage (and do not know who might) but it will help adjust each barrel for exact air balance. Hope this helps you get going. Also even my car is sputtering in the morning when cold, as it does not have any type of choke.

Thanks Vertigo - would the screws, at least two of them be the brass ones? one at the bottom left has a spring on it and the other on the right middle?

Are the other two on the other side?

T

The screw with the spring on it is the idle mixture screw. The brass screw in the body is probably a jet carrier.

I'd start tuning your carbs by checking the ignition system. Most "carb" problems are usually ignition related, esp. those carb problems that appear over time. If you're still running points, replace the points and the condenser and adjust the timing. Do a valve adjustment, as well. Only then should you start looking that the carbs.

You can pull the jet (pictured above, on the right) and see if it's clogged as well. Quick and easy first step.

yep, adjust vales and ensure the timing is correct. check the fuel and air filters to ensure servicablility. pull the idle jets (look for the little orings and inspect them), blow the jets out, and reinstall. set both idle mixture screws at 2 1/2 or 3 turns out from gently seated. make sure the fasteners on the intake bases and manifold to carbs are tightened. back the pass side idle adj off of its stop. now the drivers side idle speed adj screw (isas) will be controling both sides. if the threaded drop links are out of adj, chances are you will be fighting one of them, the throttle plates will not be open equal ammounts, and you will be chasing your tail forever trying to equalize the flow with one side mechanicly fixed further open than the other.

give the drivers side isas a few turns in and try to start the car. the idle will be high, don't worry about that right now. i recommend the unisyn type of meter. the seal on the bottom will have 2 holes in it. turn the seal so the hole in the seal is open to the hole in the body of the unisyn. this will help stabilize the needle and make it less sensitive to the pulses each carb will experience. running the idle at 2500 rpm, at this time, smooths out the pulses too.

now check the flow rate on each carb at this point. use the threaded rod on the pass side to equal the flow readings on drivers side carb. tighten the jam nuts on the rod and recheck the flow numbers. what ever the number is, as long as it's the same on both sides you're good to go. turn the drivers side isas down to achieve an acceptable idle. shoot for around 900rpm. turn the pass side isas back in until it just makes contact.

if the power loss is above 3100rpm your problem is more than likely in the main jet circuit. buy bob thomlinson's weber tech manual, available from cb performance or a local vw shop. if you are running carbs you really should have one.

k

looking at the cb book, i notice the exploded parts diagram shows a fuel screen held by a cap located under the fuel inlet. you show be able to feel it. check it out.

k