Hi folks, I have a question about Edelbrock carbs. I have been experimenting with the metering rods in my carb. If I change rods what's the best increment to go by? I have 6542 the car runs out ok but I can tell I need just a little more gas flowing, also the small springs what do I go by? I see they are color coded. On a high performance application do I want a light spring or heavy? I am using the silver springs now. What is the function of the springs?
While the website is helpful I would recommend that you call tec support. They were super helpful and helped me walk through the tunning of my carb. If you make enough of a connection with the tec person they might even throw you a couple metering rods, springs, and jets to get you going. Just ask me how I know that! Jay
Hello Pokey.....could you give us a little more information about what you mean by "I need a little more gas flowing", i.e. do you have a bog/hesitation, mid range flat spots, secondary not working properly, what color are the plugs?...do they indicate a rich or lean condition. There are many things inside the Edelbrock Carb. that can be changed to help.
To help give you an idea, metering rods are stepped, and the numbers are the size of the steps if you mic them. Your 6542 is 65 42, the tip is .042 and the next step is .065. iIf you want to make it richer you would want a skinnier metering rod as the metering rods are inside the jet (which you can also change to make a bigger change in you r mixture). At idle engine vacume holds the metering rod down into the jet to restrict it and make it lean, as you loose vacume the metering rod raises and lessens the restriction. This is where the springs come into play. a light spring keeps the rod down longer where a stiff spring lets it raise quicker.
The Edelbrock service manual is available on line free. Fred included the link above. Print it out and read it. It is full of info including easy to read charts to show you what rod/jet to use for what you need.
Hello Pokey.....gus68 has the metering rod info. on the money. A good rule of thumb is to use a spring that is rated at one half of your idle vacuum value as a starting point. You can change the metering rods, springs and or jets in an effort to get the right combination. It is similar to trying different power valves in a Holley Carb. Another area to check is the accelerator pump squirters....Different styles of nozzles and sizes are available which will increase/decrease pump shot in your tuning effort. Also along this same line are the four (4) external linkage holes in the pump linkage which vary how long and when the accelerator pump shot comes in. Also an item to check is the secondary operation if you suspect it is not coming in effectively. You may change the size of the jets but you must make sure the weighted air valves are working in your application. These air valves are replaceable with different weighed versions but are difficult to locate and purchase. You may have to modify (lighten) your existing air valves. Also these air valves are not only distinguished by the amount of weight on the valve but also the angle of attack of the blade in the air stream. Many things available to the tuner to dial in their Carbs. As you can see in my Avatar I run dual Carter AFB's 625 CFM on an Edelbrock TR1X Tunnnel Ram and it runs great against all expectations on the street. Good Luck, Bill
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