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iThing
Samba Member
Joined: February 11, 2012
Posts: 18
Location: Oshkosh WI
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 Posted: Wed Jun 04, 2025 8:54 am Post subject: 28PCI questions |
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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
The Distributor Distributor
Joined: April 27, 2002
Posts: 6810
Location: Pentwater, Michigan
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| Posted: Wed Jun 04, 2025 9:10 am Post subject: Re: 28PCI questions |
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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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1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6810
Location: Pentwater, Michigan
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| Posted: Wed Jun 04, 2025 9:13 am Post subject: Re: 28PCI questions |
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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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Roads Scholar
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018
1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc
1961 (October)Single Cab- Road Trip Workhorse
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rcooled
Samba Member
Joined: September 20, 2008
Posts: 2778
Location: Santa Cruz, CA
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| Posted: Wed Jun 04, 2025 1:12 pm Post subject: Re: 28PCI questions |
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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
Samba Member
Joined: October 20, 2007
Posts: 6359
Location: central rust belt
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| Posted: Wed Jun 04, 2025 1:49 pm Post subject: Re: 28PCI questions |
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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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