The Lotus Grand Tourers

Hi Everyone I am looking for some advise / guidance please? Having had my 912 HC engine set up on a dyno just before this hot spell and all was running great, however after a 350 mile round trip to Castle Comb this weekend including enjoyable track time, my engine has a little misfire but only when it get hot throughout the rev range although continues to pull and develop good power. Coolant is fine and never gets above 90C but as the temperature under the bonnet raises the misfire get worst i.e. stuck in traffic, once moving in cool air it's good. I am 99% sure it's fuel vaporisation which these HC engines are prone too, I use Shell V power but even this is less stable then fuel from the 80's. I do have a fuel filter/regular under the bonnet which has increased the length of hose to the carbs which I fitted when I had a aftermarket fuel pump, however now I have the standard Electronic SU pump, so I might remove this or maybe fit it in the boot on the output pipe so that I can have a short as possible route to the carbs from the fuel flow value which I could also potentially insulate?
So basically anyone else had this issue and fixed it either in Elite/Éclat's or Excels?
Thanks
Andrew

I know its the other end but how is the fuel filter?

Ignition coils can also falter if they get too hot.

Pete

Pete Boole wrote: Tue May 26, 2026 19:05 Ignition coils can also falter if they get too hot.

Pete

And where does the intake air come from?

Have you fitted steel braided fuel line, close to anything hot?
Take a wet rag and put temporarily over filters, etc.

dave the cog