Anyone who has experienced this problem may be able to help. I have an 84 1/2 Fox-chassis with a 650 Holley normally aspirated, and T5 box on a Windsor (5 Litre). It has been tuned last year and normally I think the second barrel never gets to open. But in 5th gear above 2400 rpm the engine flat spots and missfires. This does not happen at 2400 rpm or above is lowere gears including 4th. Its hard to nail because 100 kmh is about 1,600 rpm in 5th so it does not get to 2400 in 5th too often and I have to go by tacho as the speedo is past the dial. Any ideas ? Thanks. (Running premium unleaded).
