MFI Protractors and Indicator
 

This is probably a long shot. Does anyone know where to find a set of these for the 72 and later plastic stack MFI engines. Porsche Part # P228C. I am looking for a set, and will also buy a set for the alum. stacks if I can find one. PM me please.

Mike

Boy, for as crucial as everyone (Grady, CMA, etc) says these are to proper setup of MFI they certainly seem to be in short supply. Frequent requests for them here and on the Earl S board always go unanswered. Is there a secret hoard of them somewhere?
Sure would like to find some to rent or buy myself.
Scott

What are they used for?... (Pardon my ignorance)

MFI protractors were supplied to Porsche dealers (at significant cost to them) and available to owners and shops as an expensive spare part. Our host can get them for you.

There are two sets necessary: P228b and P228c. The pieces of P228b are necessary for MFI ’69-’71. The additional pieces P228c are necessary for ’72-’73 and the Carrera 3.0 MFI. You still need the P228b pump protractor when using P228c.

Protractors are necessary for measuring and setting the correlation of the linkage for the MFI pump, the left throttles and the right throttles. “Correlation” is having all the linkage moving together so the mixture stays appropriate to the specs. There is a set of specifications in CMA for the 2.0, 2.2, 2.4 and 2.7. These specs are valid for the 3.0 also.

The critical linkage issues with MFI are:
Every throttle and the pump are on the stop at idle.
Every throttle and the pump comes off the stop at exactly the same time.
The progressive correlation of the throttles and pump is as specified over the full range of motion.
Only if all the above criteria are met can you finesse the system to try and improve the part-throttle running (should only be done if you are willing to spend a LOT of time and money.)

Anyone doing this should also complete all the steps in CMA (CMA2). This is one of the VERY LAST procedures.

Yes, you can make your own versions of P228b & P228c with considerable work. If so, you need to compare to the factory tool settings. The critical numbers are just off-idle and low mid-range. It doesn’t care about full throttle, it just goes fast.

Look at this thread:
“More Fun with MFI and LM1”
How to use protractors for correlation.
http://forums.pelicanparts.com/porsche-911-technical-forum/179707-more-fun-mfi-lm-1-a.html

Best,
Grady