MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - 78 SU Spec MG Rough/rich running...opinions pls

Hi....I'm new to this board. Am an Expat living in New York and Ebay'd a 78 MGB with 39000 miles in immac. condition. BUT....(ain't there always a 'but')...it seems to run awful rich/has a lumpy idle and the plugs are well coked... Car is all orig and untouched...has the Zenith carb which seems OK. Auto choke works but even when disconected the car still runs rich & rough. Weakening the mixture has no effect on the idle, the float is OK and the needle valve is also OK. Timing is at 10...altering the timing makes no difference. Vac advance seems OK.

Do I pull the head and decoke the engine OR try a new carb...which will be expensive. Also...do I renew the Zenith or put an SU on it? Moss has them...but not cheap... don't know what to do 1st....anyone?
P J KELLY

sorry...that should read US Spec
P J KELLY

PJ,
Have you taken a look through the archives?? There are some very good discussions on the Z-S carb setup and problems, and if you go back about 2-4 yrs ago, I think you will find them. I have no experience with Z-S setups, but those who do have left you a legacy of good info and insight into how they work in the US application and how to get the most from them. You owe it to yourself to rummage through the archives abit, and see what is there. Also, see the current thread about searching the archives for some tips on that as well. Good luck!
Bob Muenchausen

Does it have an SU fuel pump and does it click more than once every 30 secs with the ignition on and the engine stopped?
Paul Hunt

There is a hose that runs from the carb to the Charcol absortion canisters. Try unhooking this hose at the carb while the engine is running. Note if there is any change in the engine idle. Then get back to us with/for more info.

John '79B
John F

P.J.
If you have points you may want to check the wire from the connection on the side of the dist to the points. If this is loose or not in good shape it can cause the plugs not to fire properly and the result is black sooty plugs.

Jerry
J W Hopkins

This thread was discussed between 14/08/2003 and 17/08/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.