'73T Weber to MFI Conversion
 

I've had my '73T for about 12 years now and I'd like to convert back to MFI. It is an MFI car. I have two questions:

How can you determine if the correct cams are in the car?

I've checked the diagram of the MFI system, but I'm still unsure of which components I need to buy. Does anyone have a listing of the parts that I would need.

Thanks in Advance,

Don

Don,

WELCOME to the forum.

The MFI cams have threaded holes in the left cam. These allow the MFI drive pulley to be bolted on. Look under with a flashlight at the forward engine tin on the left cylinder bank. Chances are, whomever did the Weber conversion did not trouble to remove the drive pulley, in which case you are in luck.

The way one identifies a camshaft is by the casting number and by the valve clearance at overlapp TDC with 0.1mm valve clearance. You mount a Z-block and a dial indicator on #1, advance to compression TDC, turn 360 degrees to overlap TDC. Then back the engine up to where the rocker moves freely-- this is your indication that the rocker is riding on the cam's base circle. Verify the valve clearance, then zero the indicator, and then move the engine forward to where the Z1 mark on the pulley lines up with the notch in the blower housing. If you remove the distributor cap, the rotor should be pointing AWAY from the radial line on the distributor body. Read the valve lift on the indicator and compare to the chart for a "T" cam.

Before going anywhere it is essential to download and read CHECK MEASURE ADJUST, the whole MFI world revolves around this document.

You need:

MFI fuel supply and return lines to tank (critical)
MFI fuel pump with three hoses connected-- S= supply, R= Return D=Druck (pressure)
MFI pump with pulley
MFI pump console (mounts to engine)
MFI injectors
MFI injector lines (steel)
MFI fuel filter console and filter with cold-start system
MFI fuel supply lines from filter/console to MFI pump
MFI pump drive belt
Cam drive pulley if you don't have it already (my guess is you do)
MFI speed switch (on engine electrical console)
Wiring for speed switch
MFI speed switch microswitch (mounts on stacks and actuated by crossbar)
MFI throttle bodies and stacks with all gaskets
MFI crossbar
MFI-specific fiberglass fan shroud (has holes for adjusting idle circuit of pump)
MFI adjustment tools (long screwdriver, hex driver, female hex)
Sychrometer


Also, you should think about a reliable way to measure AFR, such as an Innovate LM-2 wideband oxygen sensor. This is the modern way to set mixtures.

It's a lot of work! But you get 10 horsepower and there is nothing better than the sound of MFI.

Not mine and I can't vouch for condition but here is the kind of thing you would use

1972 911T MFI system - $2,100

Yep, that definitely will get you close to having most if not everything you need.
If the pump and throttle body condition is unknown...figure another nearly $2k to have the MFI pump and throttle bodies rebuilt/renewed.

Not cheap or for the faint of heart!
But as said before, there is really nothing quite like a good running MFI engine.
Good luck.:D

Unfortunately, it looks like the previous owner did a thorough conversion. No pulley, nor can I find a hole where it would connect to the cam. Does the back of the cam stick out through the cam cover? Or, does the pulley have a boss that goes into the cam cover?

BTW....Thanks for the info.

The cam boxes are identical left to right. As such, there are holes in both ends and the cam protrudes through the opposite end on each. The far end away from the cam sprocket is plugged with a steel freeze plug.

This provided the factory with a convenient way to drive the MFI pump. (And later the turbo scavenge pump, or the speedometer on early race cars).

So the end of the cam has holes in it that the sprocket bolts to. If your cam doesn't have holes, then that's evidence of a VERY thorough conversion!

In which case you must change the camshaft.

no affiliation
 

I bought a set of "E" cams for use in my carbureted motor.
I had to saw off the end of the cam where the drive pulley mounted.
I have heard that a drive pulley can be adapted to a "normal" cam by a machinist.