MFI injection pump control rod spec

[rowingone]

I am following the adjustment procedure for MFI from Rice and he states the injection pump control rod spec is 114mm and critical. My non running project 1972 911T MFI measures only 84mm . .what is the proper spec for a 72?

[ed mayo]

114 mm CENTER TO CENTER.

[stownsen914]

How could it be off by 30 mm though?

[RSTarga]

Originally Posted by stownsen914

How could it be off by 30 mm though?

Incompetence

[rowingone]

Another question . .this car has a prime switch between the seats for cold starts (formerly a Florida Car) but shouldn't there be a screw or stop installed on the MFI pump thermostat rack to keep it from running too rich? Should the pump rack be fixed in the "warm" running condition? If i can move the rack does this mean the car will remain in the rich (cold) setup if there is no heat from the riser hose?

[rowingone]

I saw a picture of a 911 owner that had a "block off plate with adjusting screw" for this removed pump thermostat . . any idea where I could get one of those?

[stownsen914]

I'm still surprised there's 30 mm of adjustability in that rod.

@Rowingone it sounds like you have a non-stock cold start switch to manually actually the solenoid that sprays fuel into the stacks for cold start. That's separate from warmup circuit on the MFI pump, which is controlled by a bellows that is actuated by heat from the heat exchangers via a small hose. The block off plate replaces the bellows, and gives more enrichment adjustment if you want to use it for that purpose. It can also be set up with a manual, cockpit mounted lever. I believe Henry at Supertec may sell a kit for that.

[tobluforu]

What do you mean by prime switch? Maybe snap some pixs of this interesting setup

[rowingone]

There is a switch mounted on the tunnel access plate between the seats. When you cold start you press the button for 5 seconds or so to prime the engine with fuel . . the switch is attached to the cold start solenoid at the top of the fuel filter which, when activated, squirts fuel into the stacks to help with cold starts.

[rowingone]

[rowingone]

here is a pic of the block off plate when you remove the factory cold start thermostat

[stownsen914]

Yup that's the one. You use that on racecars, or cars with headers, that can't have the little hose from the heat exchangers to warm up the thermostat/bellows on the MFI pump for your warmup circuit.

Here's a thread detailing the cockpit adjustable version of a blockoff plate. Supertec is the manufacturer.

https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1024900-supertech-mfi-manuel-fuel-enrichment-part.html

[tobluforu]

I've seen supertecs setup, but the prime switch sounds like a trip. I understand its function, but is this a race car? Rice's how-too along with cma pretty much is geared toward cars that have the stock mfi setup, which sounds like you don't have. Granted, most of it holds true for any mfi, but sounds like the previous owner jacked that car up. Unless it's a race car. Having that rod at 84mm is compensating for something else..

[ed mayo]

Is that a high butterfly system? That would explain the pump rod. That would be nice to know.

[rowingone]

After talking with Mark from MFI Werks I have decided to restore to stock condition. He was very knowledgeable and extremely helpful regarding all things MFI. His comment was why mess with a perfectly good system . . you just have to adjust it to factory specs and check every detail!

[r lane]

Originally Posted by rowingone

There is a switch mounted on the tunnel access plate between the seats. When you cold start you press the button for 5 seconds or so to prime the engine with fuel . . the switch is attached to the cold start solenoid at the top of the fuel filter which, when activated, squirts fuel into the stacks to help with cold starts.

Sounds as their is confusion between the cold start and the warm up, 2 separate parts of the system. Maybe I am not understanding the question. One is for start up and the other is for warm up. You can have a manual switch (replaces the thermo time switch)for the cold start. And as stated, a lever and cable to replace the thermostat. Bob

[rowingone]

My confusing was that the car I purchased had the cold start priming switch but the heat riser tube was missing and I assumed it you had the heat riser disconnected you would also have the thermostat fixed in the lean or warm position and this was not the case. I bought a project and it is all a learning experience for me. My first Porsche . . I have restored a number of C2 Corvettes but this is my first German car.

[rowingone]

My most recent restoration . . not a Porsche!
https://www.youtube.com/watch?v=ulPom8GW_O8