We used to add 10% Methanol/Ethanol to fuel on racing cars for increased power and cooling. This required larger jet sizes on carburetted cars.
On the Pembleton, after gradually increasing jet sizes, I ended up with 10% larger jets for E5 fuel. Performance is better than on earlier fuels (when you only have around 35bhp it is easy to measure performance on the public road!).
On the 4/4 I have just fitted ethanol proof fuel pipes (CBS), a newly manufactured fuel pump and increased the jetting by around 5% as a starting point- the Twin Cam is now noticeably quicker.
Carburetted cars of this era tended to be set quite weak as standard for emissions rather than performance.
