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Running hot and with run on and fast idle

Discussion in 'Bay Tech Clinic' started by Farky66, Mar 24, 2015.

  1. Farky66

    Farky66 Member

    Messages:
    275
    Location:
    Adelaide
    Hey folks,

    My bus has started playing up a bit lately so just looking for some advice on what it might be. It is idling very fast, has terrible run on and the plugs hot which has led me to assume it is an air leak somewhere.

    It first started around when I did the timing a week or so ago, so I re did the timing a few days later which made it a bit better but then it came back after a few days of driving.

    Today is the first day I have had the chance to have a decent look at it. The vacuum lines dont seem too bad from what I have checked. So far I have checked the elbows inside the engine bay, the brake booster line going out & dizzy vac line. I havnt gone as far as the brake booster, although had a look at it and couldnt see any obvious places where it might be leaking + the booster is working fine.

    I am now thinking it might be the carbies leaking. One of my carbies seemed pretty flooded when i had a look inside aswell whether it be related or not. I am yet to hit the carbies with wd40 to check for leaks as i ran out of light tonight.

    Can anyone else shed some light on what it might be or what i should check?
     
  2. Barry

    Barry Well-Known Member

    Messages:
    6,141
    Location:
    Abbotsford NSW
    what motor do you have? Type 1 or 4?
     
  3. Farky66

    Farky66 Member

    Messages:
    275
    Location:
    Adelaide
    2L, Type 4
     
  4. splitbus

    splitbus Well-Known Member

    Messages:
    3,354
    Location:
    Brisbane
    The clamp that hold the dizzy in place, is the bolt/nut stripped, allowing the dizzy to rotate slightly
     
  5. Barry

    Barry Well-Known Member

    Messages:
    6,141
    Location:
    Abbotsford NSW
    do you have a timing light

    too much advance will cause those problems

    What splitbus said is worth checking - it was the last thing you touched
     
  6. Farky66

    Farky66 Member

    Messages:
    275
    Location:
    Adelaide
    It seemed fine last time I looked but will have another look at that tomorrow. I have been doing the timing with a timing light, I did notice it was jumping around a little when I was setting it though.
     
  7. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,012
    Location:
    Penna, Hobart
    Dont guess at this stage. Start from scratch and make sure everything is set correctly. If you have eliminated all of the leaks and obvious things, you need to start with a clean slate and methodically work through to find it.

    To do your timing make sure you are idling below 1000 rpm as any higher will bring in the mechanical advance and you will get a false reading. If you have an SVDA distributor make sure the vacuum unit is working by making sure when you suck on the vacuum line disconnected from the carb, the plate in the base of the dizzy moves. If it is a dizzy with the double vacuum can make sure it works in both directions. (If it has no vacuum advance IMHO chuck it and get an original form some where with it. Dont bother with the Chinese ones.) Set it to the setting for your engine, which for an SVDA dizzy is around 8.5 degrees BTDC. When you rev it hard it should not go past 25-28 degrees BTDC at 3200 rpm. Make sure the points are clean and set to spec and there is a little grease on the cam and rubbing block.

    Once you know all this is ok you will need to go to the carbs and check they are at least opening the same. With the engine off, see if when you move the rod, both throttle linkages start opening at the same time. If not, loosen the right hand adjustment rod and make them even. If they are you might like to look at the following article. This was written for an American 1800 but the general procedure is the same for most carb driven Aussie buses 1700-2l. I have tidied it up in formatting but it is essentially the same article that has appeared on this forum before. I use it and have been very happy with the results.

    It is a PDF file and I had to zip it as it was just a little too large.

    Adrian
     

    Attached Files:

  8. Farky66

    Farky66 Member

    Messages:
    275
    Location:
    Adelaide
    Thanks Adrian, I will have a good look at it on the weekend and hopefully sort something out. That article is definitely worth the read. I have always just taken my van to someone when it comes to carbies but they might be worth a shot. What sort of synchroniser do you have? I have looked into getting one before but was put off a bit as the ones I have looked at are about $200.
     
  9. nils

    nils Well-Known Member

    Messages:
    1,523
    Location:
    newcastle
    turning your engine into a paperweight because one or both banks are running lean will cost considerably more. I use a basic vacuum gauge tee'd into the manifolds. By pinching off one side hose or the other you can read the variations, but I can't remember does the type 4 motor have an equaliser tube?
     
  10. Chidori

    Chidori Active Member

    Messages:
    923
    Location:
    Fitzroy, VIC
    I got my Carby synchroniser a snail type one from thornbury carburetor in melbourne. Cost $50. Thys what he uses. Otherwise try somewhere like mick motors is brisbane. They might have some.
     
  11. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,012
    Location:
    Penna, Hobart
    My synchroniser is a japanese one that was found at a garage sale. The type 4 motor has a balance tube that the idle mixture system feeds into, so you probably wont be able to get an accurate reading from the vacuum gauge as it will be getting an additional signal from the other side as it tries to balance. For getting a rough indication you might ba able to measure by disconnecting the balance tube and measuring the vacuum at each of these ports into the manifold at a certain rpm, but really it would be easier to just get the balancer.

    To get you close you can just get them to open visually by the same amount at various pedal settings. Also if they start to open at the same time off idle with the linkages set the same it should be in the ball park.

    Adrian
     
  12. Farky66

    Farky66 Member

    Messages:
    275
    Location:
    Adelaide
    Thanks for the replies. I will try find a balancer then as I am pretty keen to learn how to set my carbies. I finally had a bit of time to check the van out today and I found the problem. It was only running lean on one side so I took off the right hand carby and turns out the manifold had a pretty significant crack in it.

    My next problem is finding a second hand manifold then hopefully I will be back cruising.

    Thanks again!
     

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