Simon, I have done some work trying to remedy the problem. 1. Plugs are new and correct NGK 2. Compression test done before purchase - all good 3. Plug leads are a few years but seems ok. Could be fooled here... 4. Plug leads are numbered and in correct place. Will meassure them for correct resistance 5. Points removed. Replaced with Pertronix electronic ingition 6. Ignition timing will be checked again. There could be something here.... 7. Air filters have not been replaced by me. Will have them replaced for next season 8. All 12 float valves are new this summer. They where long gone... 9. Float level is checked and seems equal enough. No major difference here 10. Carbs have been balanced using vacuum. They are not 100% and needs another go Before I bought it the car had been sitting in a garage for several years,only short trips once in a while. All in all the car performs better now after the few things I've done but the irregular idle and difference in exhaust temp tells me there is something more. The idle problem could most likely be a tuning issue such as carb cleaning or new carb parts needed but I'm not so sure about the exhaust temp problem. It also has a annoying jerking behaviour at steady speed. Almost as if some of the sylinder cuts out. Could well be an ignition problem (leads,coils)?