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 - Are my Carbs running ok??

Thanks to the advice I recieved from this forum I went ahead and fitted my new Freeflow exhaust & Manifold and fitted some K&N filters to my '72 GT. The car runs fine but there are expected changes - but i don't know if they are good or bad???
Firstly the idle speed sits down at 800rpm now (I think this is too low) and secondly i have no idea how to tell how lean my carbs are running?? thirdly the car engine bay stinks like something is burning. Oh its stopped running on now??

Any ideas?? Cheers.
Kev Williams

Perhaps something, like your new exhaust system is getting hot enough to burn off things like the oils often used and sometimes left behind in traces on sheet metal??? Or if your system is painted, it could be the solvents remaining in the paint being driven off by the heat?? Some possibilities. Also look to see if any thing has shifted position and is now dangling too close to a hot exhaust pipe??
Bob Muenchausen

Assuming SU carbs then the lifting pins should tell you, but on a 72 the other way is to adjust for max idle. For a UK 18V engine 750-800rpm is the correct idle speed. Changing the manifold and filters the way you have usually upsets the mixture balance across the throttle range and you have to fit richer needles. These result in a richer running mixture (to cope with the greater airflow) for a given idle mixture. Both the usual ways of checking mixture only do so at idle. If you change the engine breathing the only sure way to check and correct the mixture across the range is on a rolling road.
Paul Hunt

This thread was discussed on 17/05/2002

MG MGB Technical index

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