73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: mikewb on April 14, 2008, 06:48:20 pm
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how do you tune air fuel mixture right on edelbrock carburetor
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you adjust the idle mixture screws one at a time by turning them in until they start to make it stumble then back them out to reach highest rpm, and stop, do the other, repeat a few times, then back each off just a touch.
You need a tach, or a vac. gauge would be better, go for highest vac. or highest rpm.
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That's only for idle quality though. To tune it while driving, you have to play with the rods and jets. If you go to Edelbrocks site, you can download the entire manual which tells you what to do. I did and read through it. Pretty interesting. And it's amazing really how complex carburetors are, considering their age and "old schoolness". For a mechanical device though, pretty neat.
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true, but I've bought several recently and new and never had to touch anything other then the mixture screws up front.
I ran them and run them now on a stock 305 with nothing else touched, then removed emissions from it, a mild 350 with 268 cam 2.02 heads, high rise dual plane intake, headers, stock 350 with 1102 summit cam and then headers with it.
They all ran fine no extra tuning required.
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Before you do anything, adjust the floats. Based on what I've heard virtually all edelbrock carbs are out of adustment fresh out of the box. Mine was. It may not be enough to make the engine run poorly, but why not take the time to make this simple adjustment and eliminate that as a point of tuning concern. Instructions for adjusting the floats are in the manual, here (http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf) (pdf format).
Then adjust the idle according to the instructions in this article (http://www.chevyhiperformance.com/howto/45638/index.html). I used it and it eliminated an annoying off idle stumble I had.
Then if you have flat spots or bogging in your power band adjust the primary metering. Determine whether the bogging occurs at light throttle or under strong acceleration, as this will tell you whether it is your cruise or power end of the rod that needs changing. This can be done by swapping out rods, jets, or both, as well the small springs that control how fast your mixture enriches. Edelbrock offers a handy tuning chart in the manual I cited above. In general, the manual is very helpful for someone inexperienced with these carbs.
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Try This!!!
http://www.telusplanet.net/public/gilesij/Volvord/edelbrock_1.htm