Zenith carb 2.4 into MFI 'T' 1973 wiring

[davidppp]

Hello all.

I would very much appreciate infromation on the wiring of this swop.

We wish to remove all the parts for the MFI system so as to fit it into another car..but are unsure which parts can be removed, and what wiring changes are needed to make sure everything works when the carb engine is in.

It looks like the speed sensor at least can be removed..but which box is this?

I assume we can ignore the wiring for the Zenith overrun enrichment system, and perhaps remove this entirely from the carbs?

No smog controls on old cars here!

Kind regards
David

Kind re

[Grady Clay]

David,

Are there two separate complete engines or are you installing Zeniths on the existing 2.4T MFI engine?

Where is the MFI system going? How complete is the MFI there (if any)?

To install MFI where there was none previously takes more than just fuel injection components.

Here is a partial list of external components:
”mfi’

Best,
Grady

[davidppp]

Hello, Grady.

How kind of you to reply!
There are two seperate engines, and I will be needing to take out all the ancillary bits requitred to put the MFI engine into another car.

Unfortunately, the Zenith engine has lost its wiring harness, so it not plug and play, and we will need to make some new wires and not sure just how..

I'm unsure of the identity of all the various boxes in the wiring panel on the left of the engine bay, and do not want to start ripping things out without being sure of making it all work again!

Kind regards
David

[Grady Clay]

David,

You are going to need an engine wiring harness from a
’70-’71 911T. That goes from the 14-pin connector to the
back of the alternator to the starter. It also includes a
somewhat separate harness from the 3-pin CDI to the
distributor and ignition transformer. I’m fairly confident
this is plug-‘n-play but you should confirm. The wiring
diagrams are available on the Pelican Tech Info Center.

You want to leave the ‘73 911T as unmolested as possible.

Here is the relay panel. This image is for a ’70 but is the
same with exceptions noted below.
ElecEngConsole70a.jpg
"
"
© Dr. Ing. h.c. F. Porsche A.G.

1 Console (aluminum)
2 Relay for single-stage rear window defroster (not used with 2-stage)
3 RPM sensor (aka SCR) only used on ’69-’70 and not ’71->
4 Relay for MFI cold start (not used with carburetors)
5 MFI RPM transducer (not used with carburetors except 911T USA)
6 Control relay for 2-stage rear window defroster (not used with single-stage)
7 Radio noise suppression
8 Voltage regulator
9 Bosch CDI (3-pin version)
10 Fuse box III

Note the 14-pin on the left goes to engine; the 14-pin at the
center (below voltage regulator) goes to main chassis wiring
harness.


What is the other car that is getting the MFI engine – year, model, condition?

You will need to remove the MFI electric pump and install a
carbureted 911T lower pressure pump. There is the easy
ability to have a circulating fuel system for the carburetors
leaving the MFI pump in place.

When you remove the fuel filter console, be sure to plug the
three holes from the wheel side of the inner fender. Seal
them in place. You should measure the position of these
holes as they may not be in the new MFI car.

Best,
Grady

[davidppp]

Thanks, Grady.

In the short term, it will be necessary for us to make a sunstitute for the 70-71 T harness from wires and connectors..the 3 to the zundbox is easy..but the 14-pin is a challenge!

I guess we can use individual bullet type female connectors.

Figuring it all out should be possible from the diagrams...

I'm guessing we can just remaove the MFI-specific boxes on the panel and leave their connections unused...?

Or will it pay to swop the whole panel for one from a zenith-carb 2.4T?

Kind regards
David

[Early_S_Man]

David,

Here is a kit that Pelican sells that has the 14-pin connector parts loose ... ready to be soldered!

[Grady Clay]

David,

Where do you live? Start with any salvage engine harness ’70-’83 as much of that will work. You are going to want to find the 3-pin CDI harness (not the 6-pin) because it has shielded wiring and you want that CDI connector and boot. Running individual wires to the CDI is an invitation for disaster some day. Using something other than the mating 14-pin probable will be very unsatisfactory.

The wiring harness in the relay panel (console) is the same ’70-’73. The only difference is the connector for the voltage regulator, the wires are the same.
Wiring harness Motorola 911.611.004.10
Wiring harness Bosch 911.612.005.10
Yes, you can just not install some components.

There are also two important ground straps:
911.612.009.00 goes from the fuel console to the chassis ground stud.
911.612.008.00 goes from the back of the CDI mounting bolt (under the nut on the back-side of the panel) to the ground stud.

We need to get Pelican rs911t to chime in here. His ‘72T I converted to Webers on a 2.8S in about ’74. This past year or two he has converted back to MFI.

Best,
Grady