Edelbrock carb poor idle

[Vincen]

I have been running an Edelbrock 500 cfm AVS2 for a couple years that has operated flawlessly. A couple days ago it became hard to start and idles rough with much hesitation while in gear. While troubleshooting today I noticed a distinct rattling noise that seems to be coming from the carb. Has anyone here encountered this or something similar?

 

[DirtDonk]

Erratic vacuum could be causing the metering rods to be oscillating up and down in their pockets. Pull your PCV valve out of the valve cover and see if it's rattling erratically too.
They sometimes rattle when the engine is running too, but most of the time you will just hear and feel a nice even vacuum signal out of them.
When you remove it from the cover, the engine speed will either go up or down and the idle will get even more rough, but you only have to check for a second or three to get your answer.

What about checking for vacuum leaks? It's really one of the first things to do when something like this happens. Could be some gunk buildup in the gas inside the carb, but the outside stuff is easiest to check first, and critically important to what you do with the carb after that.
If you find a vacuum leak you have to fix that first even if something is still wrong with the carburetor.

Good luck

paul

 

[Vincen]

Erratic vacuum could be causing the metering rods to be oscillating up and down in their pockets. Pull your PCV valve out of the valve cover and see if it's rattling erratically too.
They sometimes rattle when the engine is running too, but most of the time you will just hear and feel a nice even vacuum signal out of them.
When you remove it from the cover, the engine speed will either go up or down and the idle will get even more rough, but you only have to check for a second or three to get your answer.

What about checking for vacuum leaks? It's really one of the first things to do when something like this happens. Could be some gunk buildup in the gas inside the carb, but the outside stuff is easiest to check first, and critically important to what you do with the carb after that.
If you find a vacuum leak you have to fix that first even if something is still wrong with the carburetor.

Good luck

paul

Thank you sir

 

[Vincen]

Erratic vacuum could be causing the metering rods to be oscillating up and down in their pockets. Pull your PCV valve out of the valve cover and see if it's rattling erratically too.
They sometimes rattle when the engine is running too, but most of the time you will just hear and feel a nice even vacuum signal out of them.
When you remove it from the cover, the engine speed will either go up or down and the idle will get even more rough, but you only have to check for a second or three to get your answer.

What about checking for vacuum leaks? It's really one of the first things to do when something like this happens. Could be some gunk buildup in the gas inside the carb, but the outside stuff is easiest to check first, and critically important to what you do with the carb after that.
If you find a vacuum leak you have to fix that first even if something is still wrong with the carburetor.

Good luck

paul

After checking every vacuum connection it came down to a small hole in the vacuum advance hose. Thanks again

 

[DirtDonk]

Wow. Way to dig down into things. That’s a hard one to find, but since it affects both vacuum and ignition timing in related ways, it’s bound to cause an erratic idle.
Thanks for letting us know. Hopefully it stays running good for a while now so you don’t have to do anything but drive it!