Carter/Edelbrock carburetor float levels are sensitive to the fuel pressure.  If the fuel pressure is altered from the time one of those carbs was initially setup, then that will require a fuel float level adjustment in which to compensate.

Lorena, Texas (South of Waco)

Here is a video of mine idling at about 550 rpm and you can for sure hear the cam. i love the sound. Hey also how much fuel pressure are you guys running. My 500 cfm eddy seems to only like bout 4.5 but edelbrock recommended 5.5. 
https://www.facebook.com/ian.goolsby.5/videos/10155189035714338/?pnref=story

That very well could be. At idle ( 525  RPM )  I can hardly tell there is a cam..

Oh, yeah, he did.
I have a bigger cam and get 15",  However, mine is on 112 degree lobe centers rather than 108 like the E4.  That might cause the difference.



Lawrenceville, GA

Charlie, he says it's an E4. I can only get 12-13 with my E4 also. Stock manifold 1/2" spacer, Holey 390 and 12 degrees initial timing stock 57 exhaust headers.. . But it runs great!

11-12 inches is still very low vacuum.  Which cam do you have?



Lawrenceville, GA

Its been a while and I had forgotten about this post so I wanted to update. I ended up with my cam and intake at 11-12 inches of vacuum at idle. I called edelbrock for a second opinion as I could tell my truck liked the stock jets much better at 5000 feet above sea level. I have put the carb back to stock including the orange springs and the thing has never run better. I have checked my plugs as well and they are a perfect color.  I have the fuel pressure at 5 psi. Engine seems to be incredibly happy. After my valve adjustment I can now actually hear my isky e4 cam. Stoked. Thanks for all the input guys.

If I read your post and the chart right, you're running the natural finish 8" vacumn springs. So they're open and on the enrichment circuit at 7" as it is.

Cap off all the vacuum connections first. PVC, dizzy, brakes, whatever, and see what you've got.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Thanks a ton for all of the help fellas. I'll keep you posted as to how it works out. thanks!

Total agreement with miker and Charlie on the 7” of vacuum; that’s low.  The low vacuum needs to be addressed first before going deeply into the carb as the power enrichment cycle could be the culprit at this point.  As far as jetting for higher altitude, the Holley carbs tend to respond to a one number reduction in jet size for each 2000 foot increase in altitude.  For subtle primary jet changes on the Carter/Edelbrock carbs, both a jet and metering rod change would be required.  I’ll suggest going back to the information provided with the carb and go from there.

Lorena, Texas (South of Waco)