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Fluctuating timing

Discussion in 'Fuel System & Electrics' started by emby, Aug 25, 2012.

  1. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    Took the bus for a test drive to see how she would handle on the road.

    Clutch cable snapped.

    What a day!
     
  2. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    Whilst purchasing a new starter :umm: I was having a chat with the guy behind the counter at Mick Motors and I think a little penny may have dropped... could be something worth reviewing but was wondering if anyone had any thoughts on the following....

    Could it be that there is a vacuum leak... and that the leak is actually in the carb body itself where the port is for the vac advance on the left hand carb?

    Just thinking out loud, but could it be that the carb is leaking in air when I'm setting it and then, after driving for a bit something is heating up / blocking the leak only for the leak to unblock later? I'm thinking that this could be the case as the slight advance in the timing could be as a result of the vac advance kicking in which is moving the timing when the tube is connected. I'm gonna go home and have a tinker.
     
  3. saabman

    saabman Well-Known Member

    Messages:
    4,856
    Location:
    Goulburn
    Carb leaks are possible ...

    If the throttle bodies are worn than you will get erratic air leaks that change with throttle activation.

    I had a hell of a time getting my bus to run right - it was OK but never quiet right till I ha dthe carbs rebuilt - rebushed thottle boddies were the order of the day.

    has been running smooth as ever since - it was the best $500 I spent of the van..
     
  4. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    Hmmm... had the carbs rebushed two years ago. You never know though. Jobs you get done just don't seem to last these days. I will have to look into it. Anyone know a good carb rebuilder in or around Brissy?

    Had a chat with Graham down at Midcoast Volkswerks yesterday and it had him perplexed too. Suggestions were to possibly see if dizzy was a problem to whack in the 009 and see if symptoms persist, if so then not dizzy. Also suggested trying non electric idle jets to see if there was a problem there somewhere.

    On a good note though, just did a 450km run and the engine is running fine, not too hot and fuel consumption was under 10 litres / 100 km. Filled up when we left and only had to put 41 litres of fuel in when we arrived. The thing is like Blackbird. The faster you go, the better she runs.:cool:
     
  5. leithbro

    leithbro Member

    Messages:
    575
    Location:
    Cairns
  6. SunnyJim

    SunnyJim Well-Known Member

    Messages:
    1,924
    Location:
    carindale Brisbane
    Emby
    Not sure I am really qualified to give advice becauseeven the kombi sliding door usually baffles me, but here goes....

    Sunnyjim's journey has been a few years but what I have noticed he has become more sedate and predictable as we reduced all the variables. (No he is not on valium, that was my mum!)

    what about the mechanics of your accelerator pedal?
    We also had that stickyness problem, baffled me, replaced everything, plugs , leads, new carbie , new pertronix, new alternator , new battery, searched for air leaks and it all got incrementally better . However it still hunted every now and then. I thought what about the choke? Nope played with that sucker too.

    Anyway I replaced all the accelerator linkages underneath with new metal. they were real bad, problem gone.
     
  7. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    At this rate I'll have replaced the whole kombi :)
     
  8. Trav&Ren

    Trav&Ren Member

    Messages:
    422
    Location:
    Melbourne
    Nope, that's normal. Main idle cut-off needs a blip to activate it again.
    I'll be interested to know how you solve this problem as I have a wandering idle that I've never been able to track down.
    Trav
     
  9. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
  10. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    Still can't trace it.

    At the moment the main issue remains the idle not returning to 900RPM, but sitting on 1200 to 1300RPM. I'm assuming that as I set the timing at 900rpm that I'm not causing any overheating issues. Changed the spark plugs over last week and all looked great, light tanning only, no fluff and no oil. Gonna get back to the dizzy again just as a final check and then rip out the idle circuit piping and check there's no blockage on the air supply line.

    The search for perfection... It never ends
     
    Last edited: Oct 9, 2012
  11. Trav&Ren

    Trav&Ren Member

    Messages:
    422
    Location:
    Melbourne
    Ooops, that was in reference to when you thought it might be idle solenoids.
    For some reason I didn't get the full thread when I posted my response.
    Trav
     
  12. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    I think I read that bit about the main idle cut off on ratwell. Had me perplexed until I read it. The issue I've got is the two pilot jets.

    I'm now convinced there are at least two issues here and that the two aren't connected.
     
  13. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    OK... another day... another tinker and I think I'm narrowing it down.

    After the drive home from work I let the bus idle on the driveway for about 5 minutes and slowly watched the idle drop from 1200RPM to 1050RPM. I can also hear a slight grinding noise as the revs fluctuate. Weights in the dizzy still not returning?

    Also, tested the vacuum line for leaks between the firewall and the brake servo. Blocked off the booster line at each elbow of the manifold with some clamps and started the bus. Revved at about 1050RPM at idle, then removed the clamps one at a time and the engine revs climbed to about 1200 RPM. Sign of a leak?

    Pulled the lead off the pilot jet on the left carb, engine Revs drop to about 800. Put lead back on and revs return to about 1000RPM. Pulled the lead off the right carb and engine speed drops to about 600RPM. Funny thing is that I synched the carbs and both were pulling the same air and revving about 600RPM but it now sounds like the mix on the right carb is running rich.

    It looks like I could have to go back to basics:-
    Put in the old 009 dizzy whilst I get the 205P dizzy rebuilt. I've found a place called Performance Ignition in Victoria that will rebuild and recurve the dizzy based on factory specs for $220 plus postage (Found them on a porsche site)
    See if I can trace the vacuum leak on the other side of the firewall and get that fixed
    Put the rebuilt dizzy back in
    Reset the timing
    Reset the mixture and rebalance the carbs....

    .... and if that doesnt work...... I'm buying a transit
     
  14. saabman

    saabman Well-Known Member

    Messages:
    4,856
    Location:
    Goulburn
    Sorry Emby I am realy confused now .

    Ive seen this mentioned a few times on the forum

    what is a transit?
     
  15. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    ???

    Bank robbers van...

    Ford transit. Mark 1 or Mark 2.

    I remember camping trips back in the 70's in the UK. Friends of my parents had a Ford Transit with a Dormobile fitout. I used to look at it in envy...that was before I found Kombis.

    [​IMG]


    [​IMG]


    [​IMG]


    Beautiful in their own way though
     
  16. oldman

    oldman Super Moderator Staff Member

    Messages:
    9,547
    Location:
    Avalon Beach NSW
    Love a Transit - used to drive an ex-PMG one in the early '80s. Bullet proof bus & next best thing to a kombi I reckon. Cheers, Mark
     
  17. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    Well I think I sorted out a few of the issues today after a disaster yesterday.

    Driving the bus yesterday and I think something finally gave way in the dizzy. Revs were sitting at around 1600+ and wouldn't drop. Check in the timing this morning and it was sitting at 32btdc and wouldn't go down. :umm:

    So this morning I started chasing the vacuum leak first. Found the non return valve had sprung a leak and was letting a slight amount of air through when blowing in the opposite direction. Replaced this with a new one. Brakes appear firmer. Will know more when I go for a drive.

    Put another dizzy in.

    Synched the carbs (took a while) but now am getting consistent results with the idle cut offs removed from each bank.

    Set the idle.

    Revs now return to idle settings immediately on releasing throttle:)

    Idle revs still fluctuating:cry:

    I've done as much as I can. Now time to take it to the experts.
     

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