Can anyone give me a rough ballpark position to set my mixture screw at?The one at the bottom corner of the carb.Car starts fine,idles ok but if you rev it it starts hunting.It,s finally going to get sprayed next week,im just trying to get it to run fine for him moving it around,and obviously for thereafter.
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I haven't worked on the turbo versions, however, as far as any carbureted engine goes:
I'll take something like the mundane R1228 for example. The screw at the base of the carb is the idle air bleed, in that it adjusts the fuel-air mixture at idle. When the throttle is opened, that causes the throttle plates in the air horn to open, literally, and for all intents and purposes the idle air adjustment is mostly out of the circuit. If you want to adjust the idle air screw, you can bring it in closed and then back it out about two turns before using a vacuum gauge or a tach to maximize the setting. Do not use a screwdriver to tighten it closed or you will blunt the idle mixture screw tip and damage it. I typically would set it for maximum vacuum at idle, but because of the pollution inspections here I then would have to bring it back in a bit to lean the mixture at idle.
Now we come to a trick which is the darling of the crooked repair shop. The engine is surging and vibrating at idle regardless of the setting of the idle air bleed screw. Mechanic says the carb needs an overhaul. Three digit price. After the customer is safely out of sight, he removes the idle air bleed screw and puts an air chuck in the hole and blows it out, hopefully with some squirts of carb cleaner. He then puts the screw back in and sets the idle mixture, sprays off the exterior of the carb, and all is well. Customer thinks the carb has been rebuilt and ignorance is bliss. Bottom line: crud gets into the idle air passages and messes up the idle. Clean them periodically. If you don't have an air chuck, use a long nozzle on a carb cleaner spray can.
Next issue -- "hunting" with the throttle open? That would sound more like a float level issue or a fuel pressure problem, or an inlet needle and seat issue. Also can be caused by a vacuum leak.
The fuel filters used by the factory, by the way, are awful. I always cut the line and added an aftermarket filter.
I'll take something like the mundane R1228 for example. The screw at the base of the carb is the idle air bleed, in that it adjusts the fuel-air mixture at idle. When the throttle is opened, that causes the throttle plates in the air horn to open, literally, and for all intents and purposes the idle air adjustment is mostly out of the circuit. If you want to adjust the idle air screw, you can bring it in closed and then back it out about two turns before using a vacuum gauge or a tach to maximize the setting. Do not use a screwdriver to tighten it closed or you will blunt the idle mixture screw tip and damage it. I typically would set it for maximum vacuum at idle, but because of the pollution inspections here I then would have to bring it back in a bit to lean the mixture at idle.
Now we come to a trick which is the darling of the crooked repair shop. The engine is surging and vibrating at idle regardless of the setting of the idle air bleed screw. Mechanic says the carb needs an overhaul. Three digit price. After the customer is safely out of sight, he removes the idle air bleed screw and puts an air chuck in the hole and blows it out, hopefully with some squirts of carb cleaner. He then puts the screw back in and sets the idle mixture, sprays off the exterior of the carb, and all is well. Customer thinks the carb has been rebuilt and ignorance is bliss. Bottom line: crud gets into the idle air passages and messes up the idle. Clean them periodically. If you don't have an air chuck, use a long nozzle on a carb cleaner spray can.
Next issue -- "hunting" with the throttle open? That would sound more like a float level issue or a fuel pressure problem, or an inlet needle and seat issue. Also can be caused by a vacuum leak.
The fuel filters used by the factory, by the way, are awful. I always cut the line and added an aftermarket filter.
Carb has been rebuilt with genuine weber kit.I'll try that trick witj the airline in the air screw hole.Car just hunts at idle if you tap the throttle then take your foot off it.Ive noticed too,don't know if this is a natural thing ,but the turbo actuator rod moves back and forward with the timing of the hunting?
gtturbogordini
Member
My le car turbo does the same thing, or it did before I blew a gasket.
But If I remember the best thing to do is to take the car for a spin when it's warmed up. Give it a decent boost with the turbo, you'll probably see some smoke out the exhaust, then bring it back and idle it for a bit. Try fiddling with the screw till it's reasonably stable, again go for a little bklast. Then tweak it some more. seemed to work for me
But If I remember the best thing to do is to take the car for a spin when it's warmed up. Give it a decent boost with the turbo, you'll probably see some smoke out the exhaust, then bring it back and idle it for a bit. Try fiddling with the screw till it's reasonably stable, again go for a little bklast. Then tweak it some more. seemed to work for me
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