540 cu. in. marine engine approximately 630 HP. Canfield aluminum heads with Victor Jr. high rise intake. Swapped out Demon 800 running 88 primary and 88 secondary jets for the Quick Fuel 850 with 82 primary and 94 secondary jets. Lost 1,000 RPM and turning the spark plugs to charcoal. 7.0 psi vacuum at idle in the water currently have 4.5 power valve, but switching to 3.5. Does anyone have any experience running this carb with same type of engine and have a clue where to start at with jetting? I can’t believe I’m running so rich wide open.