Not on a boat, but on my `67 Fairlane Hardtop. Factory 390 4V Holley. I can't seem to get the surging out of it. If I set the timing where it runs good, it pings and surges. If I back the timing off, it's lazy and comes to an idle slowly, and just plain ol idles/runs like crap (along with drinking the fuel...more than to be expected). I can't remember the number of the carb off hand, but it's a factory `67 4V application. The engine has a mild cam and true 2.5" exhaust, nothing special. I've checked for vacuum leaks and have the correct PV's in it.
Looking for a little insight on something I may be missing ??? Thanks guys !!!