A7 running issues

[Robert Leigh]

In my experience with SU carburettors it is important to be sure that the piston and dashpot are scrupulously clean, and that the needle is centred in the jet. When these are correct the piston will fall to its stop with a click. The dashpot oil is usually light grade, but flat spots on acceleration can be improved by using thicker oil.
On my car I use an MGB spec fuel pump (pusher rather than sucker) mounted low down by the chassis and fed from a scuttle tank. It may be a bad idea to use an old pump whose original application may be unknown.
Even after being ignored for months the engine comes to life instantly on stale petrol, so I believe the fuel system is satisfactory.
In my picture the fuel pump can be seen

   

[Upperfield]

John, thanks for your reply, I know that the threads on the inlet side of the alloy lid on the pump are a little 'soft' so will recheck that, hopefully no air getting in, and I think I actually understand what you mean about the fuel height vs the top of the jet from reading SU books that I have, and it should be ok.  I think that yes, it is definitely 'leaning out' so will think about temperature management.  On the ethanol - E10 I'm afraid - will check around to see what else is available here in NI.

Robert, thanks for your reply too, I think that all are nice and clean but will check and definitely re-centre the jet to be sure.

Overall, it seems that I need to think about temperature and an SU electric pump!

Thanks again all - your help is much appreciated.

Hugh