Please pardon our dust while we improve the website over the next few days.  If you need anything please feel free to call 616-301-2888 or email Mike.  Thank you!

Q & A: MGB Z-S Carb

Mr. Twist-- I would appreciate your thoughts on a problem I'm having with the Zenith- Stromberg carburetor on my 1980 MGB with 10,000 miles. This carb was rebuilt 3 years ago by a very experienced foreign car mechanic. Since then, I have made idle adjustments using your article on these carbs in the Moss catalog as a guide, and always make sure there is adequate oil in the dashpot. The car runs beautifully once it is fully warmed up. The problem I have is cold starting. It must be cranked 3-4 times after sitting overnight before it catches. Then it idles high (1800 rpm), and there is a "popping" sound through the exhaust pipe. This problem only happens when the car sits overnight. After the first start of the day, it starts fine the rest of the day even if it sits for hours. The next morning it is again difficult to start, and the exhaust popping is present. This started last year. Once the engine reaches proper operating temperature, it smoothes out, the idle drops to 900 rpm, and it runs better than it ever has with plenty of power. I assume the problem is with the coolant controlled automatic choke, but don't know how to approach the problem. I want to keep this car completely original, but perhaps I should convert to a manual choke. Do you have any suggestions?
Thank you, Ed

Ed!

I understand (and applaud) your desire to keep your car original. You WILL be able to make it start easily but you probably won't be able to get rid of all the popping as long as the air pump is on the engine and is connected... read more