For a particular car, the linear function $f$ gives the predicted power, in brake horsepower $\left(\text{bhp}\right)$, for engine speeds between $\mathrm{1,000} \text{revolutions} \text{per} \text{minute} \left(\text{rpm}\right)$ and $\mathrm{6,000} \text{rpm}$. According to this function, the car's predicted power is $433 \text{bhp}$ at an engine speed of $\mathrm{3,331} \text{rpm}$ and $600 \text{bhp}$ at an engine speed of $\mathrm{4,500} \text{rpm}$. The equation $f\left(x\right)=\frac{1}{7}\left(x-a\right)+433$ defines $f$, where $x$ is the engine speed, $\text{in} \text{rpm}$, and $a$ is a constant. What is the value of $a$?