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MG MGB Technical - hif overflowing (1978 B)

Leaking overflow from one carb ,car been standing for a time can this be repaired with the carb in place ?will the base plate require a new gasket..thanks ged
ged

Probably could be repaired in place, but since it is quite easy to remove carbs, I would remove it. Likely the same amount of time either way, as time spent removing carb will likely be saved doing the job. May or may not need a new gasket - safest if you want least downtime to have one on hand in case the one thats there is in rough shape. Problem likely is dirt/varnish on needle valve, could also be leaking float (fuel in float).

Hope that helps.

Erick
Erick Vesterback

First disconnect the fuel pump and run the engine to empty the float chambers, then reconnect the fuel pump. The resultant rush of fuel through the wide-open valves often clears things, it's probably gumming if it has been standing a while.

If that doesn't then it will be much easier to change the float valve with the carb off, even though it might be possible with it in-situ (it certainly isn't on a V8, but at least on those you can take both carbs off as a unit and ot disturb the linkages). If you remove one or both carbs then really you will need to set them up again from first principles afterwards. Always replace the bottom seal on HIFs, unless it has only been replaced very recently. They harden in use and being 'under water' you don't want a leak after refitting the carbs to the engine.
Paul Hunt

Thanks all i will try the fuel trick and let you know if it works can i remove the fuse to the pump to empty the carb will this do the trick.
ged

From the factory no MGB had a fused fuel pump, but it's something I recommend fitting as both my MGB came to me with loom damage from a short in or by the pump.

On a UK 78 locate where the white/brown wires from the main harness join the white from the rear harness at a bullet conenctor in the mass by the fusebox. Pull the white out of that connector (leave the white/browns where they are) and that will disable the fuel pump.

This is where to insert a fuse to protect the wiring, het a tubular fuse holder from Halfords, a couple of brass bullets, and a 2-way bullet connector. Solder the bullets to the wires on the fuseholder and connect up. Use a standard 17amp rated, 35 amp blow fuse, this is fine to protect the wiring even though the pump doesn't take that much current, and you (should) have two spares in the lid of your fusebox cover.

It's also a good idea to protect the overdrive circuit, particularly on late MGBs with the gear-lever manual switch as the wiring on that is continually flexed back and fore and also has been known to short-out causing harness damage. Either get another fuse-holder, bullets and 2-way connector and insert it where the white/brown from the *gearbox* harness joins the main harness as the same place the fuel pump wire joins, or get just one fusehoder and bullets and a 4-way bullet connector, then you can protect both circuits with the same fuse.
Paul Hunt

This thread was discussed between 02/06/2008 and 04/06/2008

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