Any idea what's wrong

[4forty]

Chargers's been running fine all summer, last weekend, took it out for a long ride, few hours, on the way home it started popping through exhaust and running real rough at idle but smoooths out at higher revs. Also brake petal got real hard to push??? and headlights take forever to open if they ever do. Changed Plugs and checked vaccuum lines but it still it's doing the same thing., sounds like vaccuum problem?   

'72 440 , Headers, intake and Edelbrock Carb

[jg68]

Chargers's been running fine all summer, last weekend, took it out for a long ride, few hours, on the way home it started popping through exhaust and running real rough at idle but smoooths out at higher revs. Also brake petal got real hard to push??? and headlights take forever to open if they ever do. Changed Plugs and checked vaccuum lines but it still it's doing the same thing., sounds like vaccuum problem?   

'72 440 , Headers, intake and Edelbrock Carb

Does it have PBs, if so, see if the check valve on the booster is working properly or that nothing around the booster is leaking, also while its idling, step on the brake pedal & see if the engine changes rpm or acts different or you hear any hissing.

[resq302]

Certainly sounds like a vacuum leak to me.  Your engine uses and relies more on vacuum at idle than it does at higher rpms and speeds.  If you have a vacuum leak, you would certainly notice it at idle.  Do you hear any whistle noises or hissing? 

Another trick I have learned is to use a small propane bottle and go around the areas of the intake to cyl. head and carb base.  If there is a vacuum leak, the engine will either smooth out or have the idle raise a bit which will pin point the area where your leak is.

[Chryco Psycho]

popping in the exhuast is often too rich so it could be an internal leak in the carb or a fouled spark plug or bad ign wire etc

[4forty]

It has Pwr Brakes.      Thanks everyone for the help, I'll be trying some of those things this weekend (if it Don't rain all weekend)      Thanks again

[firefighter3931]

Get a vacuum guage on the carb.....Pull the vacuum hose off the PB booster and put your finger over the open end. If the engine vacuum goes up then you've got a problem with the booster or check valve. It sounds like a vacuum leak to me, but you need to isolate the location. Good luck. 


Ron