Trimatic and Emission
Originally Submitted by T:
Trimatics and Emissions:
Top Gear Switch:
From HX and LX on, Trimatics had a "top-gear switch" fitted to them.
This switch was attached to the kerbside rear of the gearbox and screwed in.
The switch was activated when the gearbox was in top gear.
The wires from the switch connected to a CFS (Cold Feed Switch) and the VAC (Vacuum Advance Control) valve on the engine.
The CFS was screwed into the cylinder head between cyl 2 and 3 in 6 cylinder cars and the VAC
was mounted under the driver's side bolt on the thermostat housing at the front of the engine.
The VAC valve permitted or denied spark advance vacuum between the carburettor and the distributor. Only when the vehicle was up to temperature (determined by the CFS) and in top gear (determined by the Trimatic top gear switch) did the car get vacuum advance.