timing and vacuum

I have a 77 ski tique I have a new engine in it.. the carburetor is a rochester model two barrel. the engine is a chevy 305. can someone please advise me on what to set the timing at. also I am told there is a vacuum adjustment for the carburetor ... how is that done as well.. cronedm@gmail.com or call 2055349321 I have spend about 9k on this boat and I am ready for the damn thing to run... thanks

In the reference section see "Blue water 198"

Sounds like your engine is rebuilt but the distributor may be old, I would put a timing light on it and watch the timing mark as you rev the engine, make sure your mechanical advance is working, you should see the timing advance as you rev the engine. It should move smoothly up until it maxes out as noted in previous post around 3,000 to 3,500 RPM and at that RPM your timing should be no more than 36 degrees. This number is far more important than your idle Timing number.
You asked about adjusting the idle mix screws. You should have 2 screws on the front of the carb, these will help adjust your idle air mix. Normally rule of thumb is to turn one in till the engine starts to stumble, then back out slowly, maybe 1/4 turn at a time and watch your vacuum reading. When the vacuum stops going up stop and do the other screw. Then repeat, work for the highest vacuum reading. The two should be adjusted about the same number of turns out from closed. Maybe 1 1/2 to 2 1/2 turns from the closed position. The amount of turns out is flexible based on how yours runs. Strong vacuum numbers = strong idle quality normally.
If your engine does not stall out or stumble as you close the screws you have a problem in the carb.