New wiring harnesses for my 1973 XJ6 Series 1

Last week I pulled the engine and transmission from my '73 XJ6. The head gasket failed last summer and I found a fully built up 4.5 litre XK engine with manual conversion and triple webers so I’m going to put that in.

But first - the wiring harnesses in my engine bay were a mess. Lots of splices, electrician tape, crimp connectors and a variety of wire colours. A lot of it came apart as I pulled the engine and disconnected everything.

I found a source for brand new S1 wiring harnesses and I’ve identified the following:

  • passenger side engine bay harness
  • driver’s side engine bay harness
  • firewall harness that runs laterally

My question is this: Before I start pulling the interior apart, where does the passenger side (large) harness connect to inside the car? Where does the driver side and lateral harnesses go? Ideally I would replace all three of these but leave as much of the interior and dashboard harness intact as possible.

Lastly: Does anyone know a source for the unique Series 1 firewall insulation? It appears to be thin aluminum over foam that is glued to the bulkhead. I traced mine before I peeled and scrubbed it off so I can replicate it, but I haven’t seen that style on any other car or in any catalogue.

Below are some photos of the old engine coming out and the new one that will be going in.

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Nice car and nice engine, Chris! Good idea to have the HT wires and the cam covers in tone with the paint:-) Signal red was offered optional and with black seats.

Not sure whether the harnesses are side-coded, but the ROM only has one picture:

Maybe this helps.

Good luck


75 XJ6L 4.2 auto (UK spec)