Here is the car 70 Duster 3510 with me in it. 360 pocket ported J heads 2.02 valve, Hughes 232/237 hydraulic cam, 9.9 compression, LD340 (divider cut down) Annular 750, (same issue with my vac. 750) 1" 4 hole spacer heddman 1 5/8" headers, 3" exh. to the bumper with ultraflows. Trans is a 727 with a 9.5 Dynamic converter that stalls about 3500. Rear is an 8-3/4 with 3.91 gears and 27" tall tire. The fuel system consist of a stock tank a 3/8" pickup (I made it myself, copied the original but made it go a little deeper in the tank) -6 braided line attaches the pickup to 3/8" aluminum line and from the aluminum line to the fuel pump is -6 braided line. the fuel pump is a holley 120 gph mechanical. From the pump to the carb is 3/8" steel line with a clear plastic 3/8" filter before the carb. I know it's not the best filter to use but I was having a problem in the summer with fuel boiling off. Nothing is near heat. I installed a return line using the factory fuel line and I put an .039 orifice in to restrict the fuel going back to the tank and it worked great for hot weather driving keeping the fuel filter full all the time. In the not so good air 2,100'DA 85-90 degree it was going mid-high 107 mph and low-mid 12.40's In good air last night 200'DA 45-50 degree air it went mid 108 mph and 12.37. I pulled a couple plugs today and they were white with black specs. I have bumped the jet size from the factory jet sizes Sorry I don't recall whats in there right now, but I went up 3 numbers in the front and 5 in the back with no change. I really think the it should have gone in the 12.20's or even the teens and close to 110 last night. I need some suggestions. I am going to try and put a fuel pressure gauge on the car to see whats going on with that. Sorry this is so long.