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Engine hiccup

Discussion in 'Engine & Transmission' started by PICT, Mar 27, 2018.

  1. PICT

    PICT Member

    Messages:
    85
    Location:
    Perth
    Looking for a bit of advice, my 1600 kombi is currently running great apart from one thing, when running at low and steady revs I get an occasional hiccup from the engine as it backfires through the carb.

    It doesn't happen when the engine is pressed only at low constant revs, my thoughts think it could be the idle circuit in the carbs not giving enough fuel either from too small a jet or a lack of pressure, any other thoughts??

    The carbs i'm using are Baby Dells (FRD 34B's)
     
  2. Barry

    Barry Well-Known Member

    Messages:
    2,540
    Location:
    Abbotsford NSW
    a "sneeze" through the carbs is a reaction to running lean

    My guess is you have a partially blocked idle jet or an air leak

    Make sure your manifolds are tight and secure and the gaskets are ot damaged.
     
  3. PICT

    PICT Member

    Messages:
    85
    Location:
    Perth
    I do know the FRD's are known to be easy to block, I checked again yesterday and I might have been checking the pump jet in the past and not the idle one :oops:, though I do know I have blown out both before. I made sure the manifold are carbs were fully tightened down. I has all helped but its still there occasionally, I'm still wondering about fuel pressure as it has always run better on a full tank than a 1/4 full tank, wondering if I need to get a longer rod for my pump to increase the pressure??
     
  4. Barry

    Barry Well-Known Member

    Messages:
    2,540
    Location:
    Abbotsford NSW
    I would be surprised if a stock set up couldnt feed baby dells

    Does it do it when cold?
    At idle? Blocked idle jets effect the idle
     
  5. PICT

    PICT Member

    Messages:
    85
    Location:
    Perth
    idle is fine, very very very occasionally a hiccup/sneeze, only really get it with slight accelerator at low and constant revs, has confused me
     
  6. Barry

    Barry Well-Known Member

    Messages:
    2,540
    Location:
    Abbotsford NSW
    What are your pugs like at idle colour wise
    After a 2,000 rev drive (ouch....hot hot)

    best answer would be to whack it on a dyno

    Still reckon jetting or vac leak
     
    David H likes this.

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