Performance Advance Curve – Improved Over Original 25D4 Engine Timing

The original 25D4 distributor curve was designed for 1970s leaded petrol and standard factory tuning. While effective for its time, the factory curve brings most of the advance in early and then levels off quickly, limiting performance at higher engine speeds.

This AccuSpark performance advance curve is calibrated to deliver stronger mid-range and improved high-RPM advance, helping the engine pull harder through the rev range. The result is sharper throttle response, smoother acceleration and better overall drivability, while remaining well suited to modern unleaded fuel.