Stromberg BX illustrated

Stromberg BX

This carby was fitted to the Holden HX HZ 6cyl engines.

Throttle shaft wear is minimal so generally don't need replacing. Sometimes the lead balls (60) will leak fuel. If you can't get the lead, get a small sinker and use that instead. They are a bit harder and you need to use an appropriate sized nail punch to insert them. Anyway for the DIY rekit you would never remove the lead plugs in the first place, unless they were leaking. Only professional rebuilders do this to clean out the passages properly during a major rebuild not a simple re-kit.

If the pump rod has a lot of lateral movement in the body slot then a little panel beating to the edge of the slot is required. This is a rather crude way to fix it but it works and lasts until the next re-kit. I use a pin punch about the width of the slot & give it a far hit from the side. Make sure the rod fits nicely & moves without binding. You won't get rid of all the lateral movement & I would advise you don't try to. All that will happen is the rod will stick & you will have to hit the rod laterally to undo the panel beat.

Make sure you fit the power jet under the power valve plunger. The power jet has the pin sticking out. To test the jet for serviceability, simply put it in your mouth to seal the head (pin towards your mouth) & suck on it. If you can draw in air the valve is leaking & needs replacing. The extra fuel required for power enters through the top of the jet where the pin is and exits through the hole drilled in the side.

Set mixture screw about 1 1/2 turns out from seated as a starting point.

There is a small welsh plug fitted in the power valve plunger. It will eventually pop out and will cause the power valve to stay on. The easiest way to fix this permanently is to fit a ball bearing in, just like in the pic.It will never come out again, ever.

The photo may not be correct. From memory the power valve plunger is staked into the air horn not screwed.

The fuel level setting is 5/8" to 11/16" below the top surface while the engine is running. This is a bizarre way to do it in my books, however this is the Holden way. Here is how I have done it from the beginning of time, statically on the bench during reassembly, never had a problem. Set the float level so that the top of the float is just off parallel to the top of the carby as shown to the left. Just press lightly on the float tang with your finger against the needle & seat. Adjustment is done by simply bending the tang.

When you fit the accelerator pump plunger, dip it in petrol first then flare out the cup end. Fit it into the bore using a circular motion so the cup slides in easier without getting caught. With most of the carby assembled less the air horn (3) put some fuel into the bowl. Test that the accelerator pump works as soon as the throttle is opened and the movement of the pump plunger is instant.