engine and drivetrain Unidentified Jet On Weber 32/36

[Hans]

I'd try it with mystery screw closed, and try to get it running with just the idle mixture screw. It should be 1 1/2 turns out to start. Lots of tuning guides online if you Google for "best idle". Basically if you go beyond a full turn in either direction, you have a jet size problem. If it runs well within that adj range, try opening the mystery screw a bit and see what happens. I doubt you will do any harm. I suspect it is similar to the extra air screw on DCOE. You can Google DCOE idle adjusting and you will see reference to those.

[adavis]

The idle mixture screw is almost exactly 1 1/2 turns out.  I'll try backing it out slowly tomorrow to see what happens.  Thanks for the help.

[allbim]

That looks like a vacuum fitting (nipple) that somebody simply plugged with a screw. I doubt that the screw adjusts anything. Why would you mess with it to pass emissions if you don't know what it does, and you have no way of knowing whether you made things better or worse?

 

Edit: I just ran across this. Take a look at the second picture in this link. It shows a short piece of hose on the fitting in question. http://www.bmw2002faq.com/topic/149601-72-vacuum-questions/

Edited January 17, 2014 by allbim

[71bmr02]

just a bit of sleuthing on google and found references to the 33b1 model on Toyota's and a discussion on a jeep forum. seems weber made a water choke model and an electric choke model. I believe what you have is a Toyota carb (others too??) which will likely work on your 02 but may take some tinkereing because of the extra jet and who knows what other internal changes. recommend you ebay it and find an Italian mfg 32/36 with choke of your liking(although I've had good luck with the Spanish made 32/36's). with carbs, the simpler the better

Gale

[Mike87]

That screw circled in red is just a plug for a vacuum port. Leave it alone...and leave it tight.

[Hans]

It may still work on a BMW, but there is the question of correct jetting. The cost of changing to BMW spec (if required) may be more than the incremental cost of selling that one and getting the proper one. Nonetheless, if it were me, I'd turn it in until seated while counting turns, then unscrew that thing and see if it is a jet, or just a plug. If it is a jet, I'd Google Toyota pages for tuning hints.  And see what the jetting sizes are.

Edited January 17, 2014 by Hans

[adavis]

To answer allbim's question, this is my first weber and the prior owner told me that was the idle mix screw.  I took car in as I got it and failed emissions.  I came back home turned that screw in and it past with flying colors.  After getting on licensed and legal, I started taking things apart and cleaning the dirty bits.  The car runs way better than it did when I got it.  Electronic ignition and a clean carb did wonders.  Learning this is not a 2002 carb makes me wonder about the jetting.  How much better would it run with proper size jets for my car at altitude.

 

So my next question is for the high (altitude) folks.  What are the correct jet sizes, emulsion tubes, etc. for a 32/36 in a stock motor that lives at 5,400 feet?

 

I do plan on putting on a 38/38 in the not too distant future, but I want to see what a properly tuned 32/36 can do. 

 

A new suspension is on the way and that should keep me busy for a while.

[TobyB]

You can answer this one for us.  Unscrew it all the way.

 

If it has a long, blunted needle on it, it's probably an idle air bypass adjustment, used to set where the

throttle plate rests at idle, and thus, where the progression ports are opened.

 

If it is just a screw, then it's a plug. 

 

There you go!

 

t

[adavis]

If you look real closely at the first picture in the thread, there is something that makes me think it is some sort of an adjustment.  I'll let you know.

[adavis]

I bet I turned the "screw" 20 full turns and it didn't come out a bit.  I am thinking there is a grove the shaft that does something.  Maybe the direction of the screw driver slot determines use of whatever this thing is.  Now I really am getting curious.  Thoughts from those smarter than me?

[Hans]

Have you tried searching on the Forum for jet reccs? I know there is a lot of stuff, and I recall some altitude based input. Or Google it. Fairly easy to remove everything in situ to read sizes, but tape over the inlets to keep parts from falling in. Basic question is: how does the car run now??

[Chamoix]

I have the same thing on new carb I bought from Redline about a year ago. Took the screw out and it is not a jet. No hole in it, no numbers on it, and no needle. Just a screw. If loose and allowing air in, may make a difference in how the carb functions.

[adavis]

Thanks Chamoix.  The screw didn't come out for me, but not going to sweat it anymore.  My car runs really well with the exception of the choke.  I converted to electric because it is a much cleaner look, but I am having a hard time adjusting it correctly.  The cold air when driving is making it hard to adjust.  The water choke make so much more sense because the coolant shields the choke mechanism. 

[Mike87]

If you turned that screw 20+ turns and it will not come out leads me to believe that it may be stripped. Cap it.

 

Adjusting the choke is trial and error. It may take some time to dial it in. I played with mine for months before getting it working to my liking. Now I have EFI, so it is not an issue.