Replace wiring harness also?
 

Is the wiring harness of a '74 1.7 roller compatible with a soon-to-be installed '75 1.8 motor?

Which wiring harnesses are you referring to?

The main body harnesses may work ok, but the two FI harnesses and ignition harnesses are completely different.

I'm keeping the '75 1.8 engine and transmission from a totalled car and installing it in a '74 roller. The 1.8 wiring harness is complete and available, however I'd like to avoid transplanting it in its entireity to the '74 car unless there is a compatibility issue or the '74 main harness is fubar.

Let's help you out Wrongpew. The 914 has an fuel injection harness going from the ECU to the injection compoents of the car. It has an engine harness from the engine to the relay plate on the driver's side of the engine compartment, and finally a short harness from the battery to the alternator. Jeff can provide you with new harnesses, so which one?
L. McC

The 74 would either have been a 1.8 or a 2.0, there was no 74 1.7 offered that I know of.

Use the 75's fuel injection wiring harness. The engine harness (i.e., the one running to the distributor) should be the same between a 74 1.8 and a 75 1.8, so use whichever is in better shape or is easier to use. Use the main chassis wiring harness that is already in the chassis.

--DD

I think that is his basic question. The main body harness should be ok...I think...

But the FI harness and the ignition harness (to the coil) from the 1.8L engine should be used with the 1.8L drivetrain.

Bowlsby understands my confusion. I should have been more specific in my question. I assumed that using the FI and ignition harnesses from my 1.8 L-jet was a given. What wasn't clear was whether or not the chassis harness from a D-jet car would support the L-jet harnesses because of a missing critical wire unique to the 1.8. Dave is correct in that there was no 1.7 made in '74. So now I have to confirm if the roller is indeed a '74 with a 1.7 engine thrown in for good measure, or if it's a 1.7 with an incorrectly stated year chassis. At any rate, I'm thankful to you all.