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Incorrect distributor and timing?

Discussion in 'Engine & Transmission' started by Trav&Ren, Sep 30, 2011.

  1. Trav&Ren

    Trav&Ren Member

    Messages:
    422
    Location:
    Melbourne
    After the dizzy rebuild on the weekend I thought I would have a look at Marvin's part numbers and it turns out that he has had quite an assorted past.

    I believe my kombi is a '76 auto, I haven't checked the chassis number.
    My fan housing number is GD022523, which is a 2lt.
    My engine number is AP048741, which is a 1.8lt '75 and I think was a manual.
    My distrubitor is a SVDA VW 021-905-205P, Bosch 0231 168 005, which is a late '76.
    My carbs are 32-34 PDSIT-2/3 and I can't see any other numbers on them but they do have the added auto bits like enrichment boxes and the bypass valve at the back (I don't have my bentley handy so I'm guessing at the names).

    So my thinking is that I've been timing at 7.5 BTDC but really I should be at 5 ATDC @950rpm. I think that's what Bentley is telling me.
    On http://www.oldvolkshome.com/ignition.htm#B7576M they list:
    Bus 1975-Early 1976 * 1800 (75), 2000 (76) Auto Trans = Distributor: VW 021-905-205AC = Timing Set At:: 5deg ATDC @ 900-1000 rpm w/strobe, vacuum hose(s) connected
    Bus & Pickup Late 1976-1978 All States, 1979 Federal * 2000 = Distributor: VW 021-905-205P = Timing Set At:: 7.5deg BTDC @ 850-950 rpm (Man Trans), 900-1000 rpm (Auto Trans) w/strobe, vacuum hose connected

    Can anyone confirm this and why autos would fire ATDC?

    Trav
     
    Last edited: Sep 30, 2011
  2. Kai

    Kai Well-Known Member

    Messages:
    4,794
    Location:
    Sydney, NSW
    That's only if you have retard. My auto svda is timed around 8btdc
     
  3. emby

    emby Active Member

    Messages:
    2,005
    Location:
    Wights Mountain, QLD
    Watch out for Bentley advice on distributor timings. I believe that the post 75 ones could be based around efi as it is a USA book. Because these buses are so old, and like you have pointed out they become a hotchpotch of parts, you should set your dizzy up based on your set-up. You have a 205P distributor so should set your timing to suit that.

    One thing 1500king pointed out a whie ago is there could be a potential error in Bentley with regards to setting the timing on a vac advance dizzy. He's always advised to set timing with the vacuum hose off and plugged for the 205P.
     
  4. Trav&Ren

    Trav&Ren Member

    Messages:
    422
    Location:
    Melbourne
    Thanks guys, this is making more sense.
    Sounds like I should just keep it the way I've been doing it (the 1500king way).

    I was hoping this might help with some misfire problems I've been having but I think it is time for a carb rebuild as my gaskets are shot and I'm assuming they're sucking in air.

    Oh, I forgot to mention that my bus originally had EFI too!

    Trav
     
  5. syncro

    syncro Well-Known Member

    Messages:
    10,362
    Location:
    Southern Highlands
    Single vacuum = 7.5 BTDC
    Dual vacuum = 5 ATDC
     

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