Losing performance after about 10-15 minutes

[PeterBo]

Have just fitted a new carburettor, and checked the manifolds for leaks etc. All appears good, no leaks and car runs beautifully. I have stripped distributor and redone timing and again appears to run at idle and speed with no problems.

So, after idling correctly and running properly up and down local hills, I then find I lose power after about 10-15 minutes. It is as though it is is running too lean and when pushed may backfire. It loses power to the point it may stop altogether but will start and run immediately after albeit with no power. Fuel feed appears OK and after it cools down, performance returns.

Suspected issues could be:

- Bad distributor capacitor
- Bad high tension coil or lead
- Something I haven't thought of but which is temperature affected...

Any ideas???? I am running out of them.

Thanks, Peter