Ferguson backfiring

Discussion in 'Classic Machinery' started by 12 bore, Oct 27, 2018.

  1. 12 bore

    12 bore Member

    My straight petrol grey fergie has developed an annoying habit of backfiring after closing the throttle down after working it, it's intermittent as well dosent always do it. Runs absolutely fine other than this ticks over nicely starts first time, not smokey at all, Am I right in thinking fuel mix or is it possible timing out or an electrical fault. Any suggestions appreciated before I start fiddling about with it.
  2. agrimax

    agrimax Member

    Co Down
    If there's an inlet valve not closing or seating right, it'll give a backfire. Check the valve clearances. Might be a burnt valve or worn valve seat also.
    10 thou inlet.
    12 thou exhaust.
    smcapstick likes this.
  3. MrNoo

    MrNoo Member

    Running slightly rich? Mine did that after I fired her up for the first time in 40 years!!! I leaned it off but suspect it's still running a tad rich, like yours starts first time, idles and runs fine. I have noticed though that when match ploughing with it at low revs, if you open it up at any point, ie to go around to take a single off, it blows plenty of black smoke.
  4. 12 bore

    12 bore Member

    You may be on to something there I think mixture wise as although mine dosent smoke normally if I was to whack the throttle open it does let out a puff or two soon clears though. I think I may look at mixture first then points, condenser and timing although as it Runs well I think this must be what it should be or close to it. Then I'll look at valve clearances perhaps
  5. Mursal

    Mursal Member

    Could be as simple as a lazy valve spring ............
    Plugs will be black if too rich should be a golden brown (never going to happen) colour.
    Just throw a different set of plugs into it (you might have a hot spot) and check when the points open with a bulb against the timing marks? Also worth running without the filter pipe to test, in case you have a restriction. Just be careful of it backfiring with no pipe attached, especially in the shed.
  6. Ley253

    Ley253 Member

    Throttle spindle bushes worn allowing a weak mixture to enter and pass through the cylinders, wont fire there but will in the silencer when joined by another pulse.
    Mursal likes this.

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