EUROPEAN SPORT ENGINES FITTED WITH WEBER CARBURETORS. FERRARI GT. Page 4. Page 5. Page 6. Page 7. Page 8. Page 9. Page Page The Haynes. Weber. Carburetor. Manual by A K Legg LAE MIMI, Don Peers, . through theory, maintenance, overhaul and tuning, using only the nec-. Engine fuel and air feed systems. WEBER CARBURETOR ADJUSTMENT SETTINGS. 40 DCOE 2 carburetor – Adjustment setting example.
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I discovered reiposavovta.cf of the original Weber Tuning Manual from Bologna. Download here. Tuning of Weber carburetors. All Weber carburetors have four circuits. Idle. Cross -over. High Speed. Accelerator. Idle and Cross-over - These circuits are. Proper idle jets are very important to a Weber's performance (this assumes there is no vacuum leaks or other carb problems check here). Idle Speed Screw.
We have included the zero by-pass valve in our jet kit. This will deliver all of the available fuel to the engine and not by-pass fuel back to the fuel bowl. This will increase the duration and volume of the pump shot with the original pump jets. This is for maximum fuel delivery from the accelerator pump circuit. The accelerator pump by-pass valve is located in the bottom of the fuel bowl, one is required per carburetor.
Be sure for initial carburetor set up all air by-pass screws should be in closed position.
These are not commonly used in standard carburetor adjustment. When doing multiple carburetors all linkage should be disconnected. All carbs should be bench adjusted to same setting.
Set the idle mixture screw to one turn out form lightly seated. When checking the seated position to make only light contact with seat, aggressive seating will damage needle and seat of carburetor, 4. Start engine as long as engine starts and runs do not set up idle speed first.
First adjustment if possible should be to find smoothest idle with each mixture screw on all carburetors. This is the number one and two reasons for tuning errors, improper linkage installations and over tightened linkage nut, causing binding in the linkage assembly.
They also have an additional air bleed screws and lock nuts.
This is not used for idle adjustment or idle quality. The settings for these screws should be closed.
Mixture Screw 1 turn out from lightly seated. Start the engine, it will run slow and like a tractor. As long as it will stay running, the idle speed is not important at this point.
The engine should start to smooth out. Then turn it back in to the point where it ran best. You want to tune the engine by sound.
Adjust each mixture screw to the best, fastest and smoothest running point. Do this procedure with each mixture screw. Now you may adjust the Idle Speed Screw.
Adjust to best, fastest and smoothest running point. Now that the mixture screw is at its best running location, you can adjust the idle speed the screw.
Check and set idle to your driving preference. Put the car in gear and apply slight load, AC on and set the Idle as you like it. Recheck timing and vacuum hook ups. Recheck mixture screw to lean best idle again. If all is still best and smoothest idle then confirm and note the final settings. To confirm settings with the engine running.
Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies.
Also check the speed screw and note how many total turns from initial contact. You may have opened turned in the speed screw. Your final setting should be under 2 full turns.
Reset the screws back in to the best final settings Per your notes and go on a test drive and have fun. If the settings are other than described then you may want to recalibrate the idle circuit low speed circuit to your engines needs.
Simple Rules for low speed calibration If the mixture screw is more than 2 turns out then the idle jet is too lean too small. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change.