75 914 Carb Conversion

[Dff Moriarty]

Changing from D-tronic to 44IDF's and am asking for some electrical direction. Have no idea how to wire up the ignition as well as what happens with the original wiring harness to the relay panel. Can someone please provide some help here. I am totally illiterate when it come to electrical so please be very detailed in response.
Thank You

[jess p]

First, remove all FI components.
Remove the FI wiring that plugs into a 5 point connector on the left rear of the relay board. Do not remove the 12 point connector on the right rear of the relay board! Remove the original fuel pump.
At your local AutoZone buy a Holley electric fuel pump rated at 7psi of fuel pressure, they cost $50.
While you are there buy some red 14 gauge wire (roll) of electrical wire 12 feet will be enough. Buy a throw 2 pole electrical switch $5. Then buy a 20 amp fuse with its associated wiring about $3.
At this point you are halfway done.
When you remove the old fuel pump you need to plug the fuel line that returns fuel to the tank. You have several options. You can remove the fuel tank and mount your new Holley pump right below the fuel tank or mount it where the original one. Either way if you can drain the fuel out of the tank for this procedure. Your new Holley fuel pump will have a red wire and a black wire. The black wire bolts to the chassis, the red wire goes to pos+ side of the battery. Now on that red wire I solder the 20 amp fuse and that on off switch. BTW on my last 3 914’s including a 75 I mounted the holly pump under the fuel tank which required me removing the fuel tank. Running the red wire by my seat to a switch with the fuse on to the pos+ of the Batt. See part 2

[Dave at Pelican Parts]

I recommend keeping the D-jet if you can.

44s are generally regarded as too large for a 2.0 914 engine, and more so for a 1.8 engine. 40s are the usual way to go.

The ignition has its own wiring harness, no need to change it at all.

The relay board has four wiring harnesses that plug into it. The body harness (14 pins), the engine harness (12 pins), the alternator harness (3 pins), and the fuel injection harness (4 pins). Only one of those involves the fuel injection, you keep the other three.

What fuel pump are you going to replace the stock one with? The stock pump puts out way too much pressure and volume for carbs.

--DD

[jess p]

The other option of wiring the new fuel pump into the fuel pump relay of the board. I bypassed that part. Now on my last 3 914’s I replaced my distributors with an 009 distributor new about $60.
If you want to keep your distributor on your 75 perhaps Dave can chime in on that. You will not need a fuel pressure regulator with this Holley pump. Your 44’s only need about 4 psi, from the fuel tank through the associated fuel hoses and a fuel filter you need to install in the fuel feed line is a 3 psi drop. Your car will run fine.

[jess p]

I agree with Dave but the key words he said was “if you can”. Appreciate that setup is now almost 50 years old. Porsche repair shops like you to keep that setup since they are one of the few that can diagnose that system. Before I converted my car It wouldn’t start and after attempting to diagnose the problem after 20 hours on the car I let a well known Porsche shop have an attempt at it and after 80 hours with it they got it running. They didn’t charge me 80 hours of labor. That’s when I said that’s it. If I’m going to appreciate these cars it has to be with a different setup. 44’s are a bit large but you can make it work.

[Dff Moriarty]

A few thing I did not mention
1. We did switch to a 009 distributor
2. Engine to 150 HP at the wheels by NWCR in Auburn Wa.
3. Electric Cooling system by Bill Santini
4. Electric Oil Cooler be EMPI

5. Custom Internally regulated Alternator. - Need info on how to wire it up PLEASE.
6. I had purchased a 2.5 to 4 PSI Holley Pump . Not big enough?

[dr914]

don't do it

[Dff Moriarty]

Don't do what?
Please explain.
Thanks

[Dave at Pelican Parts]

The Doc is, if anything, less of a fan of carburetors on 914s than I am. He thinks you should keep the D-jet.

Sounds like your engine may be non-stock enough that D-jet will be very difficult or impossible to tune. To get a real 150 HP, at least one (probably all!) of the displacement, cam, and compression have been changed from stock. An aggressive cam in particular will not play with D-jet.

With 150 HP (again, if that's real and not just "well we guess that...") the 44s may be appropriate.

I don't really know how an internally-regulated alternator would be hooked up to a 914. I know it has been done, but I didn't check how. Do you know how many wires the new alt has? The stock has three that go to the voltage regulator, and one fat wire that goes to the starter.

The low-pressure pump is good. Depending on what pressure the carbs actually need, a regulator is still probably a good idea. You should also figure out if your pump (and regulator) are built to only use a single fuel line, or if they are built to return excess fuel to the tank the way the stock high-pressure setup does. If the former, you will need to plug the return line, probably at the tank. Believe it or not, a bolt and a hose clamp are popular for that.

Good luck!

--DD

[Dff Moriarty]

Thanks for all your help Dave. We will figure out the alternator. Yes we are using an Engle Race Cam.

[jess p]

The 2.5-4 psi is the wrong pump. Holly makes a 7 psi electric pump, don’t use a regulator. For the internally regulated alternator and you mention it is a custom alternator is it a GM product? If it is look on the back of the alternator. At the top you will have a two plug connector. The two plug connector will have spades that look like this _ _
If the plug does not look like this then it is not internally regulated. There will also be Batt + terminal
and a ground plug. In addition there will be a plug( single connection) for instrumentation. Tell me what you have on the back of your Custom internally regulated alternator and I can tell you how to wire it.

[Fly Mach .86]

I have had Weber 44IDF carbs on my car for the last 19 years. I use 32 venturies, F11 emulsion tubes, 130 main jets, 175 air jets and 55 idle jets. My motor is 2.2 built by FAT Performance and produced 147 hp on the dyno. For the first few years it wouldn't come off idle well till about 2500 rpm. After experimenting with different idle jets, the 55's seem to work great. I have been using a modified hex bar linkage that works great and I have always use a CB Performance 3.5 psi fuel pump. The jets on these carbs are easy to change and may take some experimenting to find the right combination.

[neil_bardsley]

I like your linkage. It's probably the best solution I've seen for ensuring the carbs open in sync.

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