| iThing |
Wed Jun 04, 2025 8:54 am |
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I'm about to start my 36 and need to know the function and initial settings for the two mixture screws at the bottom of the carb. Also the VJBU4BR8 dist. has vacuum advance but there is no vacuum fitting on the carb. Can one be installed or ok to run with no vacuum advance?
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| tasb |
Wed Jun 04, 2025 9:10 am |
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That first picture with the spring loaded screw is where the vacuum port usually is found. On Buses there is a simple brass plug installed in that location and either a VJ 4 BR 8 or a VJ 4 BR 25 distributor is installed. Your screw is probably just acting as a vacuum plug.
The second photo is your volume control screw. The starting point is 2.5 turns out from closed. |
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| tasb |
Wed Jun 04, 2025 9:13 am |
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https://www.thesamba.com/vw/gallery/pix/2159076.jpg
Fitting need d for a vacuum line install. |
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| rcooled |
Wed Jun 04, 2025 1:12 pm |
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iThing wrote: Also the VJBU4BR8 dist. has vacuum advance but there is no vacuum fitting on the carb. Can one be installed or ok to run with no vacuum advance?
Is your distributor number actually VJU4BR8? If so, it needs a vacuum signal from the carb to operate the advance mechanism allowing the motor to run properly. |
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| esde |
Wed Jun 04, 2025 1:49 pm |
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rcooled wrote: iThing wrote: Also the VJBU4BR8 dist. has vacuum advance but there is no vacuum fitting on the carb. Can one be installed or ok to run with no vacuum advance?
Is your distributor number actually VJU4BR8? If so, it needs a vacuum signal from the carb to operate the advance mechanism allowing the motor to run properly.
Actually, if the vacuum advance is left disconnected, it will run like it has an 019. The mechanical advance inside the VJUR 4BR8 is the same as an 019
They are definitely a bit easier driving with the vacuum advance connected, but it is not needed IMO |
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