68 383

[Sixt8Chrgr]

I have an Edelbrock on my H code 383. I think it is a 600 CFM. The carb was on the car when I bought it, and does not appear to be very old. The issue I am having is during idle and very light throttle pressure. The cars has a rough idle while in gear and also with light throttle. Once you get past what seems to be the idle circuitory in the carb things clean up and the car runs good. Any ideas on what I can do to straighten this out?

[Ghoste]

Put lighter springs in the hold down for the rods?

[Musicman]

Here's a link to the Edelbrock Tech Vids... check it out, very useful information concerning Carburetor tuning.

http://edelbrock.com/automotive_new/misc/tech_center/install/tech_vids.shtml

[Sixt8Chrgr]

Thanks

[JoeyGowdy]

Here's a link to the Edelbrock Tech Vids... check it out, very useful information concerning Carburetor tuning.
http://edelbrock.com/automotive_new/misc/tech_center/install/tech_vids.shtml

Omg... those vids are so annoying is he explaining it to a kid?  Here's one of his quotes:

"First thing is, do it when the engines cold.  If you do it when the engines hot youre just going to burn your fingers..."

   

[Ghoste]

You'd be amazed though at how many people would otherwise burn their fingers if that wasn't in there; and then they'd turn around and sue Edelbrock for not warning them about it.

[Sixt8Chrgr]

Put lighter springs in the hold down for the rods?

I dont follow what you are saying here Ghoste.

[Ghoste]

The Carter style carb has a rod that fit into the jet and effectively close down the diamter of the jet.  There is a piston and a spring affair to hold it at the right level.  At high vacuum (idle) the piston should overcome the spring pressure and pull the rod down into the jet.  At low vacuum (WOT), the spring overcomes the piston and pulls the rod out of the jet to open it up and fatten your mixture.  Same funtion as a power valve in a Holley.  I'm no carb expert though so I'm guessing but cetainly if you are having an issue with low vacuum at idle or someone has already been in the carb and changed the spring, this could be a symptom.
Have you been to Edelbrocks site to look at their tech help?

[Sixt8Chrgr]

The Carter style carb has a rod that fit into the jet and effectively close down the diamter of the jet.  There is a piston and a spring affair to hold it at the right level.  At high vacuum (idle) the piston should overcome the spring pressure and pull the rod down into the jet.  At low vacuum (WOT), the spring overcomes the piston and pulls the rod out of the jet to open it up and fatten your mixture.  Same funtion as a power valve in a Holley.  I'm no carb expert though so I'm guessing but cetainly if you are having an issue with low vacuum at idle or someone has already been in the carb and changed the spring, this could be a symptom.
Have you been to Edelbrocks site to look at their tech help?

Ok I understand now. I have been to the Edelbrock site with no avail.

Thanks, will keep plugging away.

[Ghoste]

Is there a performance cam in the car?  Have you done a vacuum test on it?

[Sixt8Chrgr]

Is there a performance cam in the car?  Have you done a vacuum test on it?

Nope, bone stock.
I have had the car for one year, and this problem has slowly developed. I do need to do a vacuum test though. That is a good idea.

[Ghoste]

If it's slowly developed then I'm more inclined to wonder about vacuum leaks.  Carb tight to the manifold?

[Sixt8Chrgr]

If it's slowly developed then I'm more inclined to wonder about vacuum leaks.  Carb tight to the manifold?

Funny you ask that, you are the second guy how told me to check that. First thing in the morning I am going to check all that out. Suppose to go to a car show in the morning, but it is going to be freezing here in NC. Will go anyway.

Thanks very much for the dialogue will let you know what I find out.

Lawrence

[Sixt8Chrgr]

I found the problem :yesnod the power brake check valve was broken. The nipple that connects to the hose was cracked and then finally broke off.