Started my 454 yesterday , it ran rough for a while till it warmed up .I just put a new 3310 Holley carb on it . Also new Accel 8.8 plug wire's on . What a difference it made the engine now run's awesome. I still have to put a electric choke on and want a metering block on the secondary side of the carb.The Holley has 70 jet's in front and the metering plate is equal to # 75 jets in the rear. It seem's just about right. I also might have to advance the timing a little bit.