Clock generator up to 8 MHz using pin 3 arduino nano
The MCU Timer Outputs are hardwired to specific pins. Arduino Nano (ATmega328p) pin 3 is the MCU pin PD3 and may be connected to Timer 2 output logic, OC2B with Output Compare Register 2B (OCR2B). Waveform Generator Mode and Timer Clock prescale are the same as above. 

 pinMode(3,OUTPUT);

 TCCR2A = ((1 &lt;&lt; WGM21) | (1 &lt;&lt; COM2B0));
 TCCR2B = (1 &lt;&lt; CS20); // prescaler = 1
 TIMSK2 = 0;
 OCR2B = 1;


Cheers!