Need Help With Weber Carbs, Won't idle Options

[michael7810]

1972 1911cc with IDF40 carbs, 50 idle, 140 mains, 220 AC jets. Engine & carbs were rebuilt 13K miles ago. Plugs and all ignition parts replaced about 3K miles ago. I have not driven the car much since June, in fact I have not put gas in it since April. My car ran great the last time I drove it about 6 weeks ago. It's finally cooling off in Phoenix so I decided to get it ready for winter driving. So before starting it up I replaced the accelerator pump diaphragms and pulled the float covers off. The bowls were dry and I noticed that 1 of the floats was starting to crumble so I installed 2 new floats, set at 10mm and 32.5mm per the Weber manual. The car started up normal but would not idle. It was running rich (9.0 on the AFR gauge). I let it warm up and it still would not idle, it usually idles fine once the heads heat up to 200F. I adjusted the throttle plate stop screw in a turn to increase the idle and it barely idled, still very rich. i turned the mixture screws in all the way and it idled a little faster but still very rough. The AFR did go up to about 12.0. I cleaned all idle jets and it didn't change. Still the best idle I can get is with all mixture screws turned in all the way. I drained the gas and replaced with fresh Shell premium but that did nothing. It revs OK and runs smooth above about 2K RPM. It seems the problem is with the idle circuit. Is there a way to clean out the idle circuit without disassembling the carbs?
Thanks for any help/suggestions.
Mike

[michael7810]

So today I removed the main stacks, idle jets and mixture screws and sprayed carb cleaner thru the mixture & idle jet holes, idle jets and main stacks. Reassembled and it ran much better but not like it was. After adjusting the mixture screws I noticed they were still within 1/4 turn of being turned in fully. So I installed a set of 45 idles (was 50) and adjusted and it runs about the same except the screws are about 1/2 turn out. Since it's drivable I'm going to add some techron to the tank and drive it a few weeks and see how it does. I'm sure all you guys with FI motors are snickering at yet another example of why you should not remove the stock FI. Maybe next winter after I retire I'll install an aftermarket FI.

[porschetub]

So today I removed the main stacks, idle jets and mixture screws and sprayed carb cleaner thru the mixture & idle jet holes, idle jets and main stacks. Reassembled and it ran much better but not like it was. After adjusting the mixture screws I noticed they were still within 1/4 turn of being turned in fully. So I installed a set of 45 idles (was 50) and adjusted and it runs about the same except the screws are about 1/2 turn out. Since it's drivable I'm going to add some techron to the tank and drive it a few weeks and see how it does. I'm sure all you guys with FI motors are snickering at yet another example of why you should not remove the stock FI. Maybe next winter after I retire I'll install an aftermarket FI.

Strange...dropping the idle jets should have made it run worse unrelated to your problem,50 or 55's are the common sweet spot for idle jets for these carbs and the Dellorto's, 45's are getting lean IMO.

Are your throttle plates fully closed when you are setting the mixture screws? try disconnecting the linkages from the crossbar and see if you have more control with the screws.
How clean were the fuel bowls when you were in there ? no water or dirt ? reason I ask is you may have blocked idle circuit galleries for that reason.