I have seen a few boats without the vacume advance on HEI distributors and was wondering what the benifits are of that, what do you set the timing at and what do you have to do in the distributor for this to work.  Just wondering and it looks much better without it.   

Vacuum advance is exactly what it sounds like it is......

Without the vacuum necessary to pull it in, you will be simply shorting yourself out of approximately 12* of total advance.

Eliminate it, the load on your jet boat motor will never be low enough to make it work...You can purchase a lock out bracket for them in most cases, but easy enough to make a heavy gage wire and lock it in place. I have used steel gas welding wire with good success.

Otherwise, just leave it there and hook nothing to the vacuum port and set the timing to your desired total advance.

GT