Adjusting an Edelbrock Carburetor

Adjusting an Edelbrock Carburetor
Paradise Garage

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Never tailgate a jet-powered car.

Edelbrock carburetors are probably the easiest to work with on the market. A lot of carbs require unbelievable contortions to make any adjustments; not so on the 'Brock. The Paradise Garage Charger, long suffering quick tunes, was horribly out of whack. We're going to adjust the mixture screws so that they are metered correctly.

The carb for this project will be an Edelbrock Performer 600 CFM Carburetor with a manual choke, part #1405, as installed on a Mopar 318 cid (5.2L) V8.

This is the Edelbrock carburetor, and those two screws on the front are the mixture screws.

Note that there are two large screws on the front of the carb, just below the nameplate. These are both mixture screws, one for each side. If one is wound out and the other in, the car will stay running, but one side of the engine will run rich and the other side lean. You can imagine how that would screw things up!

To get them in sync, they have to be open the same amount. To do this, you have to know where they are now!

Keep the car running while you perform this, so that you can listen to the idle. But watch the cooling fan! (We take no responsibility if you get your fingers sliced up or cut off.) You may have to take off the air cleaner; we didn't.

Take a flathead screwdriver and open the left screw. Really let 'er rip, but on the other hand don't back it all the way out of the carb either.

This close-up should give you a better idea of what you're working with. By the way, that white object in the foreground is a radiator hose, not a thumb.

Close the right screw all the way in. Now you know exactly where the right screw is: completely closed. Open it back up, but count half-turns as you go. Open it to about five half-turns.

Close the left screw all the way. Now open it to five half-turns. Congratulations! The mixture screws are in balance.

Adjust the screws in sync (so that they remain equal to each other) until you get to where the car is running like it should. For us, it was 3½ half-turns.

The Charger feels like a different car now! It seems much faster and probably gets better fuel economy too. Of course, the proof is in the timeslips, but unfortunately that season is past in this area. We'll post results in the spring!

Postscript: After allowing the car to sit for a few days, I found it to be much harder to start than it had been, and the idle was too rough for driving in traffic. Opening the screws to 4½ half-turns has produced easier starting and a smooth idle. The details make the difference!