Volvo RWD 120-130 Forum

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It backfires 120-130

posted by  someone claiming to be Jim Hampton on  Fri Nov 28 17:42 CST 2003 [RELATED]

The kid's '65 122 isn't running well and he says it backfires (I haven't heard it). When I was putting wires in my '67, I looked at his to make certain my sparkplug wires were o.k. When I hooked mine up and tried to start it it wouldn't run. A check of Haynes showed the wires were wrong - as if 180 degrees off. His car ran well then and had good power. The timing gear had been replaced before then, but the car ran fine until now.

When I pull wires off, it is only when I remove wires from 2 and 3 that I get a drop in rpm. 1 and 4 don't have an effect. Actually, at first it seemed as if 1 and 4 worked ok, then 2 and 3. It was inconsistent. He had to go someplace and I haven't had a chance to fool around with the for a few days. I had set the timing (by ear and with a tachometer) and it seemed to run better. Any advice?

His carbs need to be rebuilt, at least re-bushed. By the way, where can I get a reamer to use to prepare to install new bushings. Is it difficult or can a run-of-the-mill backyard guy do it?

Jim Hampton








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    It backfires 120-130

    posted by  blackjackmc on  Sat Nov 29 06:30 CST 2003
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    last visit: Mon Jul 27 10:24 CST 2009
    [RELATED]

    The firing order is 1342 in anticlockwise rotation, if you have clockwise it will put 2 and 3 out.








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      It backfires 120-130

      posted by  someone claiming to be Jim Hampton on  Sat Nov 29 17:10 CST 2003 [RELATED]

      It has been a couple of weeks since I looked at the car - the kid works a terrible schedule - but the wires aren't in proer order. If I hook 'em up right the car won't run. As I said, it's as if the whole deal is bassackwards. Can I determine if the right valves are open (and closed) without taking off the timing gear cover and looking at the timing marks on the gears, etc.? Which vales are the intake and which are the exhaust valves?

      Thanks a bunch.







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        It backfires 120-130

        posted by  Grey240Polar on  Sat Nov 29 23:39 CST 2003
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        Here is what I would do:
        - remove spark plugs
        - turn the crankshaft until #1 cylinder is at TDC on the compression-stroke

        TDC is found when the mark on the distributor gear cover faces 0 on the crankshaft pulley. To make sure that it's TDC on the compression-stroke put your thumb on the spark plug hole of #1 cyl. While turning the crankshaft towards TDC: if you feel air being pressed past your thumb, that's the compression stroke.

        - with #1 at TDC, take off the distributor cap and determine the position of the rotor relative to the electrodes in the cap. Its hould be slightly past the electrode of #1 (past, because of the advance). *

        You know the firing order, so the next electrode the rotor encounters is the next cylinder in the firing order. This will help you to connect the HT-leads in the right order.

        With the valve-cover off you will be able to see which valves are open and closed, and while turning the crankshaft also the ones that are opening and closing. With the valve cover removed, you can also see which are the inlet and outlet valves because they are facing either the inlet or outlet ports of the manifold. Maybe now is also a good time to check and set the valve clearances and replace the valve-cover gasket.

        * If you want the rotor face to face with the electrode instead of slightly past, then first turn the crankshaft back slightly so that the mark faces the static advance (you can find the static advance in a manual like Haynes). If static timing is 10 degrees BTDC, then the mark should face 10 on the pulley in the 0-30 degrees part of the timing marks.







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          It backfires 120-130

          posted by  someone claiming to be Jim Hampton on  Mon Dec 1 03:21 CST 2003 [RELATED]

          Thanks a bunch. I really appreciate it. The logic is clear, isn't it. 'guess I'm not all that rational or clear-headed at this time of a semester Iguess I'm assuming that I can think sometimes).

          Jim Hampton








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            It backfires 120-130

            uid 4846's pic
            posted by  JohnMc on  Mon Dec 1 03:37 CST 2003
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            last visit: Thu Oct 23 07:42 CST 2014
            [RELATED]

            I would imagine the distributor drive gear is in 'wrong'. It's difficult to get it in the proper orientation, even assuming you know what the proper orientation should be (there's a picture of what it looks like in my Haynes manual - some odd degree with #1 at TDC). When you put the gear in it twists as it descends. And to complicate further it hardly ever engages the oil pump drive and goes all the way in the first try - you have to turn the engine around a bit until the pump engages and it drops that last 1/4 inch. All in all it's a fairly tedious and unrewarding task.

            But in any case you can always move the sparkplug wires around and twist the distributor to get everything working properly regardless of the position of the timing gear. When the crank pulley indicates 'TDC' it means both #1 and #4 are at TDC - you'd have to check which cylinder has both valves closed (peek in the valve cover or take it off) to see which one should be getting the spark at that particular TDC.

            Backfiring can also be caused by maladjusted carbs running too lean.








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    Bushings 120-130

    posted by  walrus3 on  Sat Nov 29 03:31 CST 2003
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    last visit: Mon Dec 2 14:20 CST 2013
    [RELATED]

    OK, I see now - the bushings for the carbs.
    I inherited the reamer I use from my dad. An industrial tool supply company
    can help. I use a 3/8" reamer with a long 5/16" shank. I sharpened the
    flutes on the shank end and put the shank through the carb and use it
    in a "pull and twist" mode. Stop before you reach the bore of the main
    barrel of the carb or you'll have a leak where the butterfly and the
    shaft meet the barrel and it will cause a fast idle. I trimmed the end of the
    bushing with a dremel moto-tool and #409 cutoff disks. Do this on both sides.
    There is an old hardware store here that sells 5/16" x 3/8" bushing stock
    pretty cheap.
    --
    George Downs, The "original" Walrus3, Bartlesville, Oklahoma








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      Bushings 120-130

      posted by  someone claiming to be Jim Hampton on  Sat Nov 29 17:12 CST 2003 [RELATED]

      Thanks for the info. Now I need to find out where to get the stuff. There are several sets of carbs around here needing re-bushing.

      Thanks again.

      Jim Hampton








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    It backfires 120-130

    posted by  walrus3 on  Sat Nov 29 03:26 CST 2003
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    last visit: Mon Dec 2 14:20 CST 2013
    [RELATED]

    Logic says that if removing 1 and 4 doesn't make a difference, then 1 and 4
    are not contributing any power. I'd try switching 1 and 4.

    What bushings?
    --
    George Downs, The "original" Walrus3, Bartlesville, Oklahoma







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