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For correct operation of your Hilborn injector the manifold will need to be tuned. This includes linkage and butterfly adjustments. If the injector is removed from the engine after being tuned, the process will need to be repeated. Although injector linkage is preset at the factory, adjustments will need to be performed after installation. Three piece injectors, by nature of their design, will need to be adjusted before initial startup and when warm.
Adjustments should be made in the following order:
The first three adjustments will be performed with the ram tubes, throttle linkage and return springs removed. After you are satisfied with these adjustments, reinstall the throttle linkage, return springs and set idle speed. Recalibration of the TPS may be required. The fourth and final adjustment will then be performed. All adjustments should be performed with the engine at operating temperature.
This operation verifies the butterflies are centered in the bore which removes the risk of sticking along with ensuring that the butterflies are in a fully closed position for the arc adjustments and for adequate idle speed control.
This operation verifies the butterflies are centered in the bores, which removes the risk of sticking along with ensuring that the butterflies are in a fully closed position for the arc adjustments and for adequate idle speed control. No other adjustments are required for hat or scoop injectors.
This adjustment verifies the hex link, along with the bronze arms, is at the optimal starting point for the butterfly arc adjustments.
Ensuring the butterflies on each bank are opening at the same rate is critical for correct throttle tip-in and part throttle drivability. The use of feeler gauges for adjusting the hex link for correct engine “tone” side to side will not correctly set the butterfly arc, and will result in a rich/lean condition on each side of the engine and poor drivability.
Final tuning, or balancing of the butterflies insures that each cylinder is performing the same work at idle and at part throttle. When accomplished, your engine will start and idle extremely well. For EFI applications, this step will ensure there is a good exhaust note and provide the best in drivability and engine acceleration. For Mechanical/Racing applications this step will ensure that all cylinders are at the correct temperature for the quickest front half times or optimal acceleration when exiting a turn. We have found that the use of a Synchrometer, allows us to maximize adjustments with the least amount of time. Before getting started, attach return springs and set idle speed. The engine and injector should be at normal operating temperatures.