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Thread: Cylinder 3 and 4 not firing

  1. #1

    Cylinder 3 and 4 not firing

    I seem to have the mirror image problem that Jonesy25 posted about a couple of months ago.

    Rebuilt 1600 engine from the Engine shop, using single carb. Cylinders 1 and 2 get up to operating temperature rapidly with the exhaust reaching > 130 C in next to no time, while cylinders 3 and 4 hardly get above ambient temperature. I've got spark, I've got compression and I've checked the valve clearances. I've tried three different carbs , a genuine solex 34 pict 3 and two FAJ look-alikes and two different distributors: a 009 and a single vacuum electronic ignition unit.

    I can't get tick over, the engine will only run with a bit of throttle.

    When putting all the bits and pieces back on the bare engine, I used the inlet manifold ends from a 1300 on cylinders 3 and 4 and from a 1600 on 1 and 2. Is it possible that that could make a difference? Another thought is that the intake manifold has a large bore vacuum(?) pipe sticking out on the cylinder 3 and 4 side. What, if anything should that be connected to? I've plugged it.

    Anyone got any ideas?

    Cheers,
    Nigel

  2. #2
    Hi nigel

    Most likely the difference in inlet as air to fuel ratio will be different. The vacuum hose will be for old vacuum advance distributors. Assuming you are not using them this will just need capping off. This will also be sucking in air diluting you fuel mixture. Are the tappets set on the right stroke? My issue turned out to be a flooding carb letting in too much fuel. New gasket and cured the cold running.
    Cheers

    Ryan


  3. #3
    Senior Member MicksRedNova's Avatar
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    Quote Originally Posted by Nigelf View Post
    I seem to have the mirror image problem that Jonesy25 posted about a couple of months ago.

    Rebuilt 1600 engine from the Engine shop, using single carb. Cylinders 1 and 2 get up to operating temperature rapidly with the exhaust reaching > 130 C in next to no time, while cylinders 3 and 4 hardly get above ambient temperature. I've got spark, I've got compression and I've checked the valve clearances. I've tried three different carbs , a genuine solex 34 pict 3 and two FAJ look-alikes and two different distributors: a 009 and a single vacuum electronic ignition unit.

    I can't get tick over, the engine will only run with a bit of throttle.

    When putting all the bits and pieces back on the bare engine, I used the inlet manifold ends from a 1300 on cylinders 3 and 4 and from a 1600 on 1 and 2. Is it possible that that could make a difference? Another thought is that the intake manifold has a large bore vacuum(?) pipe sticking out on the cylinder 3 and 4 side. What, if anything should that be connected to? I've plugged it.

    Anyone got any ideas?

    Cheers,
    Nigel
    If your using a single carb I would suspect:
    Plug leads wrong cylinders. Don't fall into trap of thinking its only 3 &4 that need checking, if your 1 step out all round the dizzy you can get an engine running but not properly. Check Haynes manual plug lead diagram (may also be in modification manual I think).
    Big air leak on 3/4 twinport manifold gasket.

    I think the 1300 vs 1600 manifold have same bore so unlikely to cause problems at tickover speeds.

    Confirm valve clearance at tdc by poking lolly stick in plug hole.

    Good luck.


    Mick
    Club Nova Member (F-036)

    MicksRedNova2 may take as long as the original!!

  4. #4
    Senior Member
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    Quote Originally Posted by MicksRedNova View Post
    If your using a single carb I would suspect:
    Plug leads wrong cylinders. Don't fall into trap of thinking its only 3 &4 that need checking, if your 1 step out all round the dizzy you can get an engine running but not properly. Check Haynes manual plug lead diagram (may also be in modification manual I think).
    Big air leak on 3/4 twinport manifold gasket.

    I think the 1300 vs 1600 manifold have same bore so unlikely to cause problems at tickover speeds.

    Confirm valve clearance at tdc by poking lolly stick in plug hole.

    Good luck.


    Mick
    I agree with you there Mick, my neighbor has an old austin a35 and it sounded awful!
    Servicing it proved to be a nightmare and replacing the plugs and leads led to even more of a headache since it flat refused to work with the new leads.
    In the end, my old man called upon a friend who knows his way around austins (he restored a few and owns one) and had it running within minutes; timing, AND leads were all over the place. He pulled the leads, reset the timing and set the leads in the proper sequence, and now the old girl purs like a kitten!

  5. #5
    Thanks for your replies. Especially for putting my mind at ease about the different inlet manifold ends, Mick.

    I've checked the position of the spark plug leads a number of times. I've sprayed WD40 on the inlet manifold while the engine is running to see if it gets sucked in, but there wasn't a change in engine revs.
    The extra pipe on the inlet manifold is plugged.

    Someone elsewhere has suggested that it could be the fuel pump not delivering enough fuel. I had put an additional gasket underneath it to get the stroke down to spec. I'll try taking that off and see if that makes a difference.

    I'll keep you informed.

    All the best,
    Nigel

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