What is being accomplished by this jumper?

By car has been converted to carbs with the fuel pump relocated and re-wired to the front of the car.

Click to view attachment

It's for the heater blower. It's a factory 'hack' when they changed from the early on-engine heater fan, to the later body-mounted heater fan. The early fan wiring was part of the engine harness, later cars have the fan wiring in the body harness.

Thanks Mark - I could see it going to the heater relay on pin 11 but wasn't sure why. Also my car worked fine without it - no heater in this car (Kerry Hunter headers), so this jumper won't be there.

Cheers!