911 SC engine forward date OXS system.
 

Recently replaced worn out engine (plus 250,000 miles!) in '78 SC with rebuilt '80 engine. Already have the later SC exhaust catalytic converter with O2 sensor. Believe it still needs the K-Jetronic "brain" (normally under passenger seat) and harness to connect: O2 sensor, brain, and fuel control devices (frequency valve, fuel distributor) together (?). Will any '80 to'83 SC "brain" and harness work to allow adjustments to meet Cal. smog test?

match the O2 lambda system to the engine year as they change around the components throughout the years

+1. Each year has a little difference in the components and even the harnesses for them.

The plug up in the engine compartment off the front of the engine is either 6 prong or 12 prong.
You need to know which to buy before spending money
Bruce

Thanks for all your input. This along with diagrams in Bentley may be enough info.

There are 2 different harnesses. You will need the one that matches your engine. I have one of them, I forget which, and it's for sale. The connectors are different, but so are the wires, so you can't just change the connectors and be done. If you provide a picture of the connector on your engine harness, I'll see if I have the chassis harness you need. BTW, Install the harness BEFORE you stab the engine and tranny. MUCH easier!

The Cap'n

Why?

The early CIS system should run the later engine just fine, and will be a lot simpler.

If he swapped over the whole early CIS system to the '80 long block, it would run. It wouldn't run as well as the stock '80 engine installed correctly. The point is he's swapping a complete engine, not just a long block and he needs the control unit for the newer engine to run correctly. A '78/'79 CIS system is very different from an '80.

JR

"Simpler", yes, if you don't count the clutter of the EGR, and AIS, and that it uses a significantly lower compression ratio as part of the system. In this case, when given a choice, the later engine is always the way to go. This is especially true in California. The car will, however, need to be smog tested by the referee the first time, which is actually FAR less expensive than going through a regular smog station. I just went through this with an updated '77.

The Cap'n