Too much timing?
Incomplete burns.
Part of the reason for left over HC is 'heavy' components of gasoline take more heat to vaporize.
For example, this 8% eth fuel began to vaporze just over 100 degrees F, same as the non-eth. But it required over 300 degrees to vaporize the last 20% of the fuel.
It needed over 400 degrees to completely vaporize all of the fuel.
Race fuels are different. Most finish vaporizing at lower temperatures, even oxygenated ones.
Incomplete burns.
Part of the reason for left over HC is 'heavy' components of gasoline take more heat to vaporize.
For example, this 8% eth fuel began to vaporze just over 100 degrees F, same as the non-eth. But it required over 300 degrees to vaporize the last 20% of the fuel.
It needed over 400 degrees to completely vaporize all of the fuel.
Race fuels are different. Most finish vaporizing at lower temperatures, even oxygenated ones.