XJ6 & XJ12 Series I, II & III 1968-1992

Xj6 series 2 350 conversion wiring

Old 02-11-2019, 02:24 PM
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Default Xj6 series 2 350 conversion wiring

Hey y'all

i recently bought a 1974 series 2 xj6 with a chevy 350 CID conversion and none of the instruments in the dashboard are hooked up.

It is running fairly well, but I'd really like to have a few things working so I know that I'm not gonna blow a head gasket or something equally horrific.

I'd really like to get the oil pressure and water temp gauges working first and foremost.

I don't know which wires to attach to the gauges to see if it's even wired correctly before getting even deeper into it.

Can y'all help??

Here are some pictures.

Old 02-11-2019, 07:40 PM
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Looks like none of the wires were cut. Thats good

Volt meter... easy, just needs a ground and switched 12v
Oil pressure... get the Jag sender and plumb it on to the oil port on the of the SBC near the dist. Should all be 1/8 NPT and may need a T fitting to have both idiot lamp and gauge.
Fuel guage is simple enough, switch 12v on one side and grounds through the sender on the tank,. Indendant of the engine,- guage sender wires go to through the tank selector switch too.
Coolant temp, just use the Jag sender and plumb it into the intake manifold or head. May neeed an NPT bushing to be used as a reducer. Depends on the port size on the intake or head.

Tachometer, will need to adjust a 6cyl tach to 8cyl.
- Many ways.... this one is imprecise but close enough to get the idea.... Tachometer Mod for V-8 Conversion...
This is better... Universal Tachometer Signal Interface
The best way is to replace the guts of the floppy Jag tach with a modern digital full sweep tach but you have to void the warranty on a new tach to make it work.

Speedometer, Does the speedo cable spin when you drive? If so plug it into a mechanical Jag speedo and see what you get. If not... you will need to get the other end of the cable in to the transmission speedo interface socket.

A wiring digrams will help, see here.
Compact but this is the one Ive use for years on many conversion.

In your engine compartment there should be a white multi pin plug for all the engine data wires that run back to the gueges, There is a pig tail that goes to the engine, Jag used 1 pig tail for the v12 and another for the I6. This pigtail sometimes gets lost during a conversion but it can be found new or used here and there.

Last edited by icsamerica; 02-11-2019 at 07:45 PM.
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jessesolo (02-26-2019)
Old 02-11-2019, 07:52 PM
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Ah that wiring diagram should help mightily, thank you so much.

Ill be giving this another shot in the morning, but I can tell you that the pigtail is definitely still in there and connected. There were definitely a lot of wires cut throughout the engine compartment and trunk, but those may have been related to the actual/heater etc
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