MG Car Repair: 1976 carb., zenith stromberg, zenith carb

Question
Hi Barrie

I have a 1976 MG midget that you have helped me with before , but now it seems I am having a problem with the carb . it's the one that came on the car , a zenith, single carb., it will set and idle perfect but when I mash the gas and I can mash all the way to the floor the RPM's don't change, everything seem to be working on the outside of the carb, throttle is opening and all , but rpm's don't go up........ Everyone is saying the carb need rebuilding,,,,, is that a major job ? Others are telling me I need to replace the zenith carb. with a different kind , say the zenith has always given problem , If I do replace with a different one, what kind should I get and from where can I get one,,,, or should I simply rebuild ?

Thanks for you help

Answer
Hi Steve.  In the USA the 1976 Midget had a single Zenith Stromberg carb.  I think your problem is a sticking piston inside the Stromberg.  When you open the butterfly, the piston does not rise, so the engine does not pick up speed.  It needs to be taken apart and cleaned, and it probably needs a new diaphragm.

If you can afford it (and if the law in your state permits it) then I recommend that you throw the Stromberg away and fit the twin SU carbs fitted to the UK Midgets.  There would be a BIG improvement in performance.