If your Formula Ford 1600 engine is having a problem with inconsistent spark timing, consider replacing the timing chain!
The timing chain is under a lot of stress, driving the camshaft (with high-strength valve springs), the distributor (through a scroll gear), the oil pump (through another scroll gear), the fuel pump, and sometimes a tach drive. The stock single-row chain (required by FF1600 rules) is just barely up to the task and should be replaced at every rebuild.
This is the stock 46-link timing chain for the Ford 1600 Kent engine. It works with the original cam and crank sprockets, and is legal for all racing series.