tomurne

I have a 600 cfm Edelbrock on my '78 L82 with a performance cam. What do you suggest is the best way to set the idle on this carb? I set it using a vacuum gauge - setting idle screws until I get max vacuum. I've read Edelbrock's set up procedure to tune by rpms. Anyone out there have preference of one over the other?

MakoJoe

The stock idle speed in gear is 500 RPMs and 750 RPMs out of gear with an automatic tranny in almost all the years from 1968 until 1982 with the 350 engine. Getting maximum Vacuum at idle speed is not a bad way to tune the engine and it will probably fall into this range of RPMS but might be a bit higher. You do not want the Idle Speed so high it clunks into gear on an automatic tranny. So somewhere between 650 to 750 RPMs out of gear and around 500 RPMs in Gear.

Cams will generally lope very well at either of these 2 RPM speeds. I love the sound of the early model high compression engines and the performance cams. Installing the performance cam in a later model has the same affect on sound.

My carb needs a serious rebuild and even with the Idle Screw turned all the way out so it does not touch it is running a high idle about 850 RPMs out of gear and 650 in Gear. Next project in restoring my 1977 Vette.

drwet

You've got the right idea. Set your idle mixture for highest vacuum reading. I find with a lumpy cam you need to richen it up a little from there to get a smooth idle. You'll also likely need to set the idle speed a little higher with a cam. I set mine at 850 in neutral, which gives me about 700 in gear.