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Tips and Tricks for your Holley or Edelbrock


  1. Edelbrock air/fuel mixture screws vibrate out

  2. Holley burns rich or idling high with the low idle screw not even touching

  3. Tips for either carburetor PVS or CSC switches.

Edelbrock Performer

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I have had continued problems with the idle mixture screws vibrating out of adjustment on the Edelbrock Performer. I would tune it and drive along a week or two and my performance and gas mileage would go down the tubes. Finally after the third or forth time I came up with this solution:

Take two small plastic caps

Drill a small hole in the edge of each cap

Use a small piece of ridged wire to tie the caps together

Adjust your fuel mixture screws and press the caps into place

I used two coaxial connector caps off some TV equipment I had purchased to stop the Edelbrock self-adjusting problem. If you do not happen to keep every little piece of junk (like I do), you could also make do with other small pipe or hydraulic fitting caps. If the only ones you can find do not quite fit you can heat them with a lighter and crimp them with pliers to get them to fit tight on the head of the screws.

Holley Truck Avenger

Secondary Idle Adjustment

I as many people have had a problem with my Holley Truck Avenger idling to high and burning rich. Anything I tried every adjustment I could find fast idle, curb idle, air mixture...etc. Nothing seemed to help. Finally after removing the carb and putting it on the make shift pedestals described in the Chelton's Holley Manual, I found the secondary idle adjustment screw. 

On the downloaded Holley.pdf file it says to unscrew the screw until it is not touching the arm and then screw it in 1 turn, but the Chelton's Manual says 1/4 turn back in for the 4150?!?! Well since my problem seemed to stem from "to much", I decided to go with Chelton's 1/4 turn back in. Now it seemed it did not idle fast enough during cold idle. After so frustration and procrastinating to pull the carb again, I found a way to adjust it on the manifold.

With the extremely convenient placement of this adjustment screw (and I thought the high idle screw was bad) you will need:

A very small 1/4" ratchet with a small 1/4" socket and 1/4" or less flat screwdriver bit.

Alternatively, a very small right angle flat ratchet screwdriver may work.

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The key to this is having a tool with a very small ratchet head; normal 1/4" socket sets will not work. The tool has to ratchet because of the limited room there is to turn the screw and the multiple possible positions the screw cold be in.

Tips for either Carburetor 

Some tricks and techniques can work with any carburetor.

One trick that works well with Broncos is to use the heat activated switch originally intended to open the EGR diaphragm, if you are no longer using it, you can use it to act as a vacuum advance delay.

On the Holley, use the original two-port switch as a CSC (coolant Spark Control) this will keep your engine timing retarded until your engine warms up. Retarding the timing will cause your engine to warm-up faster and help stop it from coughing and/or stalling during off idle acceleration.

On the Edelbrock, get a three-port switch to use as a PVS (Ported Vacuum Switch) to give extra vacuum, which increases the idle during high coolant heat situations such as during prolonged idling in traffic. The PVS will also slow an acceleration vacuum jump that causes the “flat spot” on these carburetors.

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Here are some pages out of the MightyVac user manual. (The only place I could find information on this subject)

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The only drawback CSC's is that it may reduce your fast idle causing the need for adjustment. PVS's do not effect fast idle.

If you have not disabled your EGR, you can get the switch from your local Ford dealer. They are available in several different heat ranges coded by color. Most parts supplier's employees will give a blank stare when you start asking for vacuum switches so here is a listing I received with my three port PVS from a local NAPA parts supplier.

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