Basic Weber carb tuning struggle

[Tremelune]

I rebuilt the Weber 40 IDA 3C carburetors on my 1970 911T 2.2 (after adjusting the valves and doing the ignition timing) using the Parts Klassik kit (which was complete and seems to be of high quality), and now I'm trying to tune them on the car. I cleaned out the passageways with pipe cleaners, carb cleaner, and compressed air. I soaked everything brass in Carb Dip and then put everything including the carb bodies in an ultrasonic cleaner with Simple Green.

My first immediate question is: What is a good starting place for the air correction screws (the ones with the lock nuts)? I have them one turn out from all the way in...an arbitrary location I just made up in my head.

I've got all cylinders drawing about the same air, according to my unisyn.

This is my jetting (it's stock, as far as I know):

venturi - 30
main - 125
idle - 55
air correction - 180
emulsion tube - F26

These are the procedures I'm following:

http://www.performanceoriented.com/new-page-2

https://www.pelicanparts.com/techart...arburetors.htm

It certainly runs better and smoother than it did before I cleaned the carbs, but judging by the smoke coming out of the tailpipe when warm, it's running very rich. When I turn the mixture screws in, the idle doesn't always change noticeably. One some cylinders I'll turn them all the way in with no effect I can notice.

I'm almost certain the engine internals are stock, and the only jetting I changed was to switch the emulsion tubes from F3 to F26 and replace a few mismatched air correction jets (that I believe had already been drilled out to 175 or 180), so it's either just a tuning issue or something bigger inside the engine...I'm hoping for the former.

This is my first time tuning a carb on a 911, and I'm out of my element...The Performance Oriented guide is Very Involved, and the Pelican guide is rather...blasé...I couldn't find a video.

[John912]

I've rebuilt 3 sets, thorough cleaning is key. You may not realize that one of the passages is partially blocked after you've cleaned. Not sure if Kurt at Parts Klassik or others still offers this service, but he would ultrasonically clean the bodies, replace throttle shaft bushings, set throttle plates, and plate key parts. I'd put them back together and make basic setting including checking pump shot and float level. -- Each worked great, only needing basic fine tuning.

One time I decided to rebuild a a 912 Solex set, shafts were tight, but couldn't get one side right. Sent it to Kurt; one of the passages was partially clogged. I'd spay in carb cleaner and as long as it came out the other end I thought it was "clean." Not! Again, thorough cleaning of carb bodies essential.

[Tremelune]

I think I've got them pretty damn close after turning the air adjuster screws all the way in to start...Missed that bit the first reading through. Some sniffs and pops off idle, but it's rare, and hasn't really shown up when driving. It's for sure running smoother and stronger than before!

Does anyone know where I can get vials for measuring the accelerator pump output? I bought (what I thought were) tiny plastic suckers, but they still don't quite fit, and I'm scared I'll get one in and never get it out...I might be able to get it by drilling a hole and putting the wire through instead of wrapping around...

[Phil Planck]

On 40IDF you can remove auxilliary venturi to make it much easier to get a vial under the squirt tube. May not apply for 40 IDA

[TheTorch]

Got some at Amazon. I could not find packages of less than 200 !

https://www.amazon.com/gp/product/B07P7GCBM7/

You can safely wrap the wire around the lip and the lid without fear of dropping it into the intake. I recycled the 198 I didn't use, sorry.

[edmayo]

And then I smear JB weld around the wire so it can't come off.

[Vintage Racer]

Ed Mayo really understands the carbs and all things early Porsche. He helped me fix a 1969 Porsche 911T. I am a big fan.

[1QuickS]

I had an "official" glass vial for years but dropped it and that was that. I now use an insulin syringe, better graduations due to small diameter resulting in longer length and more resolution between level lines.