1977 porsche

[ubcnme2]

has anyone swapped a 2.7 motor out for a 3.0 motor if you what electrical in the engine bay needs swapping ? cd box ? engine plug into the cd box ? what else. thanks ubcnme2

[Walt Fricke]

UB

This is a common swap, but you need to search the Pelican lists to get answers. They are there in full detail, so no one needs to reinvent this wheel.

You already know about the CD box change, it seems - different number of pins in the box and connector. The 14 pin plug needs to have some of the wires put in different positions. The later 3.0s used a frequency valve, which requires installation of the mini-brain those cars used, along with a relay. More if you want to use the O2 sensor.

I was told that the tach signal from the 3.0 won't work with the 2.7 and older electronic tachs, so I bought a 3.0 tach. Otheras seem to claim that this is not necessary, but is something you should be aware of in any case.

You can figure out the wiring yourself by comparing the diagrams for the old and new setups, though you will find a post somewhere telling you what changes to make.

I did this back around 1990. My Euro 2.7 '77 did not have power assist brakes, so I blocked off the vacuum source at the motor until I installed the power brakes some years later. When first I did this I skipped putting in the mini-brain, although luckily the donor motor came with all that stuff. It was hard to start and didn't idle well. Putting in the electronics solved all that for me. The oil tank vent lines are a bit different, so I fixed things so I could still use the 2.7 system into the airbox before the flapper rather than into the boot after the air was measured. The later 3.0s limit revs by cutting off the fuel pump, with differfent circuitry. You can install a Euro distributor rotor with a mechanical rev limit like your 2.7's (different size, so you can't just use your 2.7s).