Does clustering the AES Sbox look up table to 32 bit entry per index, help reduce vulnerability to cache timing attacks?
The answer to this sort of question would depend greatly on your hardware (both your CPU and cache architecture).

On the other hand, I don't see this adding any protection on common hardware.  When a program on (say) an Intel chip does a byte access, the CPU generally issues a read for a larger segment (often the cache line), and then extracts the desired byte from it.  From the CPU's and memory's viewpoint, reading the entire line is no more expensive than reading a single byte (the memory bus is designed to pull in an entire line at once), so it might as well access it all (and so fill in the entire cache line, just in case you access other parts of that same line in the future).

So, you're doing manually (via explicit instructions) what the CPU is likely able to do automatically (and cheaper; it already has the hardware in place, and so it doesn't spend extra cycles to do so); I would expect that this is a waste of time.