i have a holley 4160 600cfm 4 barrel vacuum secondary carb on a 351w. It is almost new. Recently i have had problems when i come to a stop and put on the breaks with the clutch depressed the engine wants to sputter and bog and almost die. I have the idle set around 1000 rpm so it doesnt stall. Sometimes i will have this problem but not always. It seems like the faster i stop, when the engine is idling, the more it wants to sputter and die. But when i am sitting still or while it is bogging i step on the gas and rev the engine a little it will clear up and idle fine. It is just the force from stopping the truck that makes it idle rough. Do you have any ideas on what this problem may be? Thanks

 

Guessing here but float level in rear fuel bowl? I'd check float level in both bowls.

 

jimbo,

I agree that your float levels may be off. Also, check for vacuum leaks especially with the power brake booster. Lastly, make sure that you have your idle mixture set right using a vacuum gauge. It should be set just a bit lean from the maximum vacuum reading. Not enough to really see any appreciable drop in the vacuum gauge, but a little leaner. The motor should be able to easily idle around 600 to 700 rpm.

Good luck,

Mark