Synchronization of carburetors (Honda Accord 3)

The Prelude's dual carburetors are designed to operate in sync, meaning that the same amount of air is drawn into each carburetor. The carburetors are synchronized as an assembly and generally do not require adjustment for the life of the vehicle. If the carburetors are removed and disassembled, they must be resynchronized.

1984-87 Prelude

Warning: This procedure requires a Honda special tool or equivalent.

1. Remove the air cleaner cover and filter.

2. Remove the air intake screens and flanges.



3. Install timing adapters (tool 07504-SB00000 or equivalent) to each carburetor inlet; tighten the nuts only to 5 Nm.



4. Connect the tachometer and start the engine. Allow the engine to warm up thoroughly until the cooling fans come on at least once.



5. Use the carburetor timing tool to measure the flow ratio through both adapters. If the flows are the same, turn off the engine, remove the adapters and reassemble the air cleaner. The test is complete.

6. If the flows are different, loosen the adjusting screw lock nut and adjust as necessary. The adjusting screw only affects the right carburetor, so use the left one as a base. Turn the adjusting screw clockwise to decrease the air flow; counterclockwise - to increase flow. If air flow cannot be balanced, inspect the carburetor or carbon tip on the throttle body for air leaks.



7. Tighten the adjusting screw lock nut. Recheck the flow ratio.

8. Stop the engine. Remove the synchronizer and adapters. Install the flanges and air intake screens.

9. Assemble the air filter and cover.

1988-90 Prelude

1. Disconnect the red braided hose (marked PURGE) from the tank. Connect a vacuum gauge to the hose.

2. Connect the tachometer and start the engine. Let the engine run until it reaches normal operating temperature; the cooling fan should turn on at least once.

3. Turn the idle speed adjusting screw until the engine speed reaches 3000 rpm. Note the value on the pressure gauge.





4. With the engine running at 3000 rpm, clamp the smooth red vacuum hose under the throttle body and note the change, if any, on the gauge.

5. If there is no change on the pressure gauge, the carburetors are correctly synchronized.

6. If there was a change when the hose was pinched, adjust the timing screw until the values no longer change.



7. Remove the vacuum gauge and connect the PURGE hose to the canister. Remove the tachometer.

8. Reset the idle speed.