Running rich?

Hi,

I recently bought a 1980 series 3 2.25 petrol swb. It has been running fine but when I took it for a run out yesterday the idle revs appear to have dropped to a level at which the engine would occasionally stall and the engine appears to be running very rich as there is a lot of backfiring and crackling from the exhaust when lifting off the throttle, even between gear changes.

I am a novice with a spanner but eager to learn. Can anyone give me some pointers as to how I may go about diagnosing the problem and making the necessary adjustments? I assume it is carb related.

Many thanks.

remove the carb carefuly, strip down and clean, then put it in the bin and buy a weber conversion

I should check the float needle it may be sticking and flooding engine

Thanks. Please assume I have no knowledge of the workings of a carb. How do I adjust the float needle? Do I need any special tools?

I would start with some more basic things before stripping the carb!

At least check to see if you are actually over fuelling as s start. Check your plugs - if you are over fuelling you would normally expect to have black plugs and check them all.

If it is overfuelling, what should I do? Thanks.

Check the distributer cap the rotor arm and check and adjust the points and clean and regap the plugs before you pull the carb to bits.

Thanks for the responses. I'll give this a go.

Backfiring on overun is a symptom of being lean, this could be caused by a loose carby, or loose manifold to head bolts.
Its possible that the engine is lean on idle and rich on power which would be a carby issue, get a can of carb cleaner and drown it.