Hot weather problem

[Bluebottle]

I have a problem which occurs only in hot weather (so not very often here in the UK!!), and which became very obvious last week when the ambient temperature hit 30C. Once the engine was fully warmed up and the water temperature got into the third quadrant (70-90C), when I accelerated hard in 2nd. or 3rd., it was fine until it hit 3,000 rpm but then it started coughing and emitting pops and bangs from the exhaust and would go no faster. I also had problems re-starting when I stopped for fuel.
Any ideas? All suggestions much appreciated. Thanks.
'63 3.8 FHC

[johnetype]

Any sort of electronic ignition module/distributor/123 etc. or still on conventional points?

[mgcjag]

Pops and bangs it typically unburnt fuel igniting in the exhaust....check timming...and ignition

[JerryL770]

Sounds like a dying coil to me.

[caveman]

Do you have Lucas/original style Black rotor arm fitted in distributor? If so, change it out for a Red rotor from The Distributor Doctor. I had similar symptoms and then it worsened to cutting out. Rotor arm was faulty. Plenty of information on this forum.
https://distributordoctor.com/collections/rotor-arms

[mgcjag]

Original poster also posted on JL and has solved his problem...iv asked that he gives an update here...Steve

[Bluebottle]

Thanks for all your suggestions. I am now 99% certain that the problem has been solved.
The cause was one or other of the following, or a combination of the two:

The central pin in the distributor car was fractured, and fell apart when the cap was removed. I assume that it was held in place by spring pressure because the car drove mainly OK, but that when it was under heavy load, the connection may not have been good enough to provide a decent spark. So new cap and rotor arm fitted.
The advance curve on the distributor (123 electronic type) was incorrectly set at 0, now re-set to 6.
She now pulls strongly right to the red line (and feels like she would like to carry on!) and although the temperature was not so high today, it was still pretty warm, so I think we’re sorted.