I have a 1995 502 .030 over, Holly 750, DUI distrib, 502 zz cam, all compression readings within 5 psi @ 155. The boat is a 27' Powerquest, bravo1 w/ 23 mirage prop. My question is what is a good idle timing # and what should my total advance be. I run 89 ethanol free gas. What is the proper way to slowly advance timing? I have heard to make a full throttle run, note rpm and gps speed. Advance 1 degree make same direction run. Do this till no more increase w/ advance then back off 2 degrees. Is this a good method?

I have a similar engine and was told 34* full advance, and let the initial timing fall where it may. Mine falls at 18*.

Also make sure you run a minimum 12g wire to the DUI. It makes a huge difference.

34 was the # I have heard, I am at 28 now so I hope there is speed to be gained. I ran 12 gauge wire right from my main breaker thru a relay controlled by the ign switch. Thanks for the input

28 is too low, makes for high exhaust temps firing that late. Need to get it up to 34. Total advance is what's important here. More at idle than normal won't hurt. With a big cam more timing at idle will give you a cleaner, crisper idle.

That's good news, is my proposed method of adjustment proper? Also I an running a Daytona sensors A/F ratio gauge and seeing 13 at wot, a little on the lean side I think?