Hi,

Has anyone experience with this vacuum take off screw for the Weber (how and where to screw it in)?
It has a thread of m5 (5mm x 0.8mm).
I want to use it for my 2 vacuum gauges to synchronize the Weber and I assume/hope 2 of these vacuum take off screws are a perfect solution.
I just do not want to have to tap the thread in the Weber ....

Anyone?

Frank

Hi Frank
The only spot is either side of the intake manifold just below the carby. You
will have to disconnect the vacuum lines that provide the vacuum signal for
the ignition module. The threads are already M5 so the adapters will screw
straight in.

Except , maybe , the 750 with the koukusan ignition doesn't use the vacuum signal and there may not be holes already there ( not sure ). My SS had the vacuum ports on the actual manifold runners , so that's probly the best place to drill if you have to . Works better if you can file a small flat on the runner and then drill square to that ..... helps with sealing

I was just looking for a vacuum take off which I can close simply without screwing it out of the manifold.
I saw this screw but was told it won't fit the 44DCNF's.

Hi Frank,

Last year I synchronized my Paso's carburetor using a home made 'gauge' (Two connected bottles of water, I got the inspiration from this YouTube video https://www.youtube.com/watch?v=7D_f05_a74Y )


The take off screws can be screwed in at each side of the inlet manifold, so not in the carburetor itself. My carb is a DCNF 44-107 by the way. See pictures. I started with adjusting the idle mixture screws so that the engine would idle at 1000-1100 rpm. Then I connected my vacuum gauge, restarted the engine and looked whether the water level in the bottles changed. Naturally it did, indicating the carbs were not synchronized. So then I adjusted the two air balance screws in small turns until the water level in the two bottles stayed constant. With this the engine is running more or the less OK. Below 3000 rpm with a cold engine it's quite terrible, as we all know. Once the engine gets warm, it's a lot better, but not perfect. Above 3000 rpm it's running well. I guess it's the maximum I can get out of the Weber without major set up changes.

By the way, it's (virtually) impossible to perform this operation with your fuel tank installed. Therefore I made a temporary project fuel tank out of an old lense fluid container See last picture.

Good luck!

Weber 44 DCNF 107 - pic 3 - RH side.png [ 994.03 KiB | Viewed 5471 times ]

Hi Ronald,

Hope al is well.
I have a set of proper (professional) vacuum gauges, so that's not a problem for me.
My questions is: the 2 vacuum nipples to be bolted in the intake manifold, if they are not in use, do you remove them or do you close them?
I hate to bolt a nipple in the manifold and have to remove them every time I have synchronized the weber.
That was the reason I was interested to buy me the vacuum take off screw (just half a turn and it is open and afterwards half a turn and it is closed again).


Frank

Frank, just cap them with either a rubber cap or a short piece of hose with one end blocked off. FYI you should only need to adjust one screw to balance the vacuum, adjusting both screws can have adverse effects in off idle transition.Something these carbs are prone to.

Hi Frank,

After synchronizing I removed the two vacuum nipples, and replaced them with M5 screws sealed with a little bit of Loctite 222 on the thread. Just to be sure everything is sealed properly. Loctite 222 is the weaker version of Loctite 243, designed for joints that have to be taken apart every now and then.