I just put on my 4-hole 2" spacer. Seems to run a tad bit smoother in take off but not a lot. barely noticeable. Its an isky cam slight lope good for street performance. I will have to look up the specs. I am smelling a lot of gas while driving too but i dont see leaks anywhere.

Sorry maybe I missed it above but what jets for primary and secondary would you recommend for my area? thanks

I'd do whatever is outlined in the excellent tuning manual that came with the carb.

But we need to know the cam specs before any more advice can be offered.  Like miker said, 7" hg is either a huge cam or a vacuum leak, both of which have their own tuning issues.  If it is a huge cam, you probably are undercarbed.  If it's a vacuum leak, then there is no sense trying to tune anything until the leak is fixed.



Lawrenceville, GA

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)

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

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

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.

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



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!

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