Adjusting Weber 32 ADFA

[tartan18]

After looking at several manuals I still cannot figure out where to find my idle and mixture screws to adjust my carb. My car is a 1975 124 Spider and if you can help I would really appreciate it -- the car often has a small back-fire when starting up ... one only ... so I think the mixture is on the lean side. The car also idles around 1100 rpm.

[So Cal Mark]

the first pic shows where the mixture screw should be, but it looks like maybe it's broken off. The other thing I noticed is that your crankcase breather vacuum nipple is capped off. Why?

[tartan18]

Yep, I thought it might be the one that is broken off. Is there a way to repair this? I'll hook up the crankcase breather hose tomorrow. I thought that might be missing as there is an empty tube on the air cleaner.

[So Cal Mark]

it depends on how it broke off, cross threaded or bottomed will probably require drilling. I may have a decent base I could sell you for a few bucks. I'll check tomorrow when I get in the shop. The nipple with the red cap should be connected to the air cleaner nipple

[opus10583]

it depends on how it broke off, cross threaded or bottomed will probably require drilling. I may have a decent base I could sell you for a few bucks. I'll check tomorrow when I get in the shop. The nipple with the red cap should be connected to the air cleaner nipple

Hi Mark,

On my car that port is connected to a nipple on the larger crank breather hose nipple on the rear side of the aircleaner base which vents into the clean side of the aircleaner plenum.

...Why?

Is the breather nipple providing negative pressure to some passage or element in the carb base, or is the carb base providing negative pressure to the breather under low load circumstances?

Thanks,
Mark

[opus10583]

it depends on how it broke off, cross threaded or bottomed will probably require drilling. I may have a decent base I could sell you for a few bucks. I'll check tomorrow when I get in the shop. The nipple with the red cap should be connected to the air cleaner nipple

Hi Mark,

On my car that port is connected to a nipple on the larger crank breather hose nipple on the rear side of the aircleaner base which vents into the clean side of the aircleaner plenum.

...Why?

Is the breather nipple providing negative pressure to some passage or element in the carb base, or is the carb base providing negative pressure to the breather under low load circumstances?

Thanks,
Mark

[bradartigue]

The idle screw is hard to see - it isn't in the pictures - but is under the water choke. You can get to it with a stubby flat head screwdriver.

As far as your mix screw, I don't see it. It may be capped off - which would have been an emissions control thing but I thought was never done to the ADFA (it was done to the ADHA).

[woodyredhead]

Hello I have a 1978 spider with the same carb....Weber 32 adfa and my idle stop solenoid has 2 wires going to it. just curious as to why this one only has 1 wire to it. thanks for your time john

[124JOE]

Hello I have a 1978 spider with the same carb....Weber 32 adfa and my idle stop solenoid has 2 wires going to it. just curious as to why this one only has 1 wire to it. thanks for your time john

mine also has only one wire/78 adfa

[tartan18]

Because I started this thread I wanted to let y'all know that my carburetor issues evaporated when I bought a new EMPI 32/63 DFEV from Mark Allison. I haven't got the new carb installed as I am waiting for the machine shop here in town to finish up with my cylinder head.