If you find that you lose sync intermittently at certain RPMs, it maybe down to ignition noise. You can either try to lower the Dwell of the coils in the dwell table (this will result in lower spark energy however). The other option is to add a noise filtering capacitor (as typical in OEM installs) to your ignition coils power feed.


A suitable capacitor is such as RS Part 7111056 (10,000uF 16V capacitor).


It should be connected with its +ve terminal to the 12v feed near the coil pack(s) and its negative connected to the engine block.