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MG MGB Technical - First start up in 20 years

I have been working on my dads 79 bgt been sat in his garage unmoved for 20 years I have finally got her running after rebuilding the carbs however I need to dynamic time and tune the carbs as she isn't running quite right. One thing bothering me is on start up with full choke the revs go to 2000 rpm which seems a little high to me but when warmed up a little push the choke in and she will idle around 800. Shall I dynamic time first then tune the carbs. Any thoughts and opinions appreciated. Carbs are twin hif.
C Carter

Christian,
well done getting it running. Are you joining the big boys for yourself or your dad?

Always RAC (Rockers, Advance, Carbs)

2000rpm on full choke at start-up is not unusual but when you get the thing set up warm and at idle, you might want to check the fast idle setting. If it idles (smooth) at 800 hot it can't be far away from right.

MGmike
M McAndrew

Rockers are all sent up so will but a timing light on it tomorrow then finish setting up the carbs. Few more bits and pieces and it should be ready for an mot. Idle seemed high to me but then again I'm used to my midget. The bgt will be my dads summer car as I could never part with my midget.
C Carter

There is a fast idle cam actuated at full choke, once the car fires up you can push the lever in until its no longer enriched but runnng at abot 1500 RPM. Now the engine wont stall but you are not petrol washing the bores. As you pull away or go uphill (both where I live) you will need to enrich it a bit while its still cold and you are asking it to do some work. It should idle smoothly at 800 rpm, but you can set it where you like within limits. My cammed car will idle smoothly at 900 or 700 but not inbetween. I set it to 700 and then you can pick the idle speed up a bit on the fly using the fasst idle cam.
Stan Best

My 78 GT had spring loaded valves in the carb butterflies which caused variable idling speeds. These are easily changed for the earlier ones.

With the air filters removed it is easy to see if the you have the earlier flat disc butterflies of the later ones with large spring valves on the disc.

If you have later ones then swap them for earlier to improve idle and air flow. This isn't expensive and is worth doing.

John.
John Prewer

This thread was discussed between 13/09/2012 and 16/09/2012

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