Okay heres the deal .My mild 408 in my Dart ran 7.50's at 91 mph before .I made a few changes like subframe connectors ,hotter plugs ,more fuel pressure and a sealed hood scoop and an air horn on top of the 750 speed demon carb .It picked up to a 7.39 and 93 mph .Im thinking the scoop setup helped me the most of the changes ,and i think i should change the jets to a bigger set.It has stock 76's in the primaries and 83's in the secondaries.The plugs were fresh on the last time to the strip and after 2 hard passes they look perfect.They are a nice light tan and clean .They shows to have good timing and good heat range.How much should i go up to start with ?Im thinking maybe 77's up front and 85's in the rear.Its a mechanical secondary carb and it runs real crisp now.My 60' is 1.63 with a 3,000 stall and 4.10 gears.The car runs great im just trying to gain all i can optimizing what i can .Thanks for your help...

When I do jetting I jump 2 jets at a time till it slows
down in MPH then back up 1 size... remember it can still
be fat with color on the plug.... tune for MPH

I would probally do as Mr P says, jet it up until it slows down and also jet it down until it slows down I like my plugs to be real clean with almost no color on a cold plug Test,test and test some more