Mike, Grady -

I have a set of protractors, but I don't know if it is complete. I can post pictures if someone who has used them can:

A) Tell me if the set is complete, or what is missing
B) Explain how to set up and use them

Based on the above, it should be clear that I have absolutely no clue on their use and effectiveness.

If the whole setup is there, I have no problem sending them out on loan to those in need.

Kevin,

The protractor set consists of two P-Tools; P228b and P228c.

P228b contains the protractor for the pump and a pair of protractors for the left and right 2.0 and 2.2 throttle bodies. It also contains three wire pointers.

P228c contains only two protractors for the 2.4 and 2.7 throttle bodies and two pointers.

I keep the pointers new and unused (after 35 years) and make brass brazing rod replicas. It is very easy to inadvertently leave the pointers on an engine and you have to bend them around to set zero.

There is an illustration of the protractors on page 8 of CMA. It doesn’t show the pointers.

Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf


The correlation instructions are in CMA.

Best,
Grady

Here are the protractors (2 sets) and some pointers.


http://forums.pelicanparts.com/uploa...1094587066.jpg


Best,
Grady

Jeeez...my Webers are looking better all the time!

Actually, a set of PMOs is looking better!

HI,

The CMA does not tell me enough about how the protractors are installed and how to read them. Do you have to unscrew the nut on the throttle shaft or do they simply slip over? Not much room in there...

I'd love to borrow the 2.4 / 2.7 set and give them a shot. With them in hand and the CMA I bet I could figure it out.

Mike,

The round object in the center of the protractor is a magnet
that holds the protractor on the throttle shaft/nut.
The strange slots, holes, and notches index the protractor on the linkage.
They are very easy to install, no tools required.

The pointers require the removal of a nut on the stacks-to-throttle body.
Leave the flat washer off and reinstall the nut.
Remember to install the flat washer when you remove the pointer.
There is a good illustration on page 17 of CMA showing
a protractor on #4 intake of a 2.4/2.7.
Here is an illustration for the #4 intake on a 2.0/2.2.
"
http://forums.pelicanparts.com/uploa...1094656450.jpg "
(C) 1969 Dr. Ing. h.c. F. Porsche A.G.


The setup for the #1 cylinder is the same as #4.

The protractor for the pump mounts on the pump lever (left side of pump)
and the pointer mounts under one of the cover screws.

It is important that the magnets be firmly seated and
positioned where they won't move around.
The "zero" must be set and regularly checked for movement.

I do the initial settings when the engine is at room temperature,
Porsche is adamant the final setting be done on a hot engine.

Best,
Grady

HI,

Thanks for the info. Your picture reminded me I have the 2.2S metal stacks but I think 2.4S throttle bodies so not sure which set I would need.

My mechanic is steering me to the PMOs but I will fight it out to keep the MOJO of the MFI!!!! I have been running MFI since 1984 and I don't want to give up!

Here is my old '72S in 1986, that Jake was talking about. I have much of it's original 2.4S engine on my new car (long story...)

http://www.analogman.com/911/72sas1.jpg

Mike,

The pair of protractors for the throttles goes with the throttle bodies not the stacks. The protractor for the pump fits all.
P228c is just an addition/supplement to P228b. Everyone would (should) have all five protractors to make a set.

A couple of tidbits: Always operate the throttle by pushing on the throttle linkage alongside the 1-2-3 stacks, never on the cross shaft or individual linkages. Otherwise it will mess your correlation measurements and coming off idle settings. I prefer to do all the setting with all the throttle ball linkages clean with just oil. After everything is perfect, go back and grease all the ball cups keeping everything in the same position and orientation (very important.) The grease will change the settings slightly until it is driven and been hot several times.

If someone is starting from scratch on this procedure, it is desirable to make sure all of the ball cups on the throttle links are free to be adjusted with AntiSieze on the threads. If you have the early aluminum links, leave them alone – they will probably break when you try and unscrew them.


The main issue with all this linkage and adjusting is:
1. The idle is proper on all six.
2. Every throttle butterfly and the pump lever come off proper idle at EXACTLY the same time.
3. The air and fuel maintain proper correlation throughout the full range.


Cool ’72.

Best,
Grady

Great information....

Are these protractors still available? CMA suggests 9 degree angle for the throttle valve and to measure CO at constant 2400 RPM at operating temperature of 80 degrees for a 2.4L. In the absence of the protractors, is there a way to approximate these settings?

Ron,

I’ll bet these are still available. Call your local PCNA dealer and ask. I do some searching. Many older Porsche dealers and shops have them. Some would love to become better trained in their use. Perhaps you can help.

The answer to the question about alternatives is yes. However, you want to spend your effort making your 911 run best possible, not manufacturing compromise tools when the original is available.
If you “approximate” these, you will probably eventually have to start from scratch with every setting.


Best,
Grady

Did something bad happen to that pretty old targa, Mike?

I hope not!!! Someone saw it on my racing web site a few years ago and wanted it more than I did. I was not driving it enough to keep it so I hope it's in better hands now.

This weekend I will try a few more things


- install new fuel filter

- double check timing

- check fuel pump pressure and output

- install stock muffler so I can run on the street, and set midrange adjustment for good reading at part throttle. THen I will check full throttle and see if it's way too lean, as I fear.

- install AUX BOX with RPM sensor and other inputs (pressure, Gs, etc).

HI,

Installed AUX BOX for LM-1. Pretty cool. Mounted it on rear floor. Ran a T from my vaccuum line to it, and tapped into the "points" wire near the CD box and sent that up too for RPM. Also clamped the included temperature probe wire to a header for some EGT readings.

Vaccuum is hard to read as it's backwards from what I would prefer to see on a vaccuum guage (up full at 14.7 atmospheric/full throttle, goes down when you idle or let off the gas). G meter is built in, I need to cal it better but shows some useful info. Can't figure out if it has cornering Gs or just front/rear.

I pulled off the megaphones and put the sport muffler back on, for Lime Rock, needed to lean it out 3 clicks. Now back to good mixture at idle, and 1/2 throttle, and too rich at small throttle openings and too lean at high RPM full load. I may try richening the manual thermostat screw and leaning the part throttle to see if that works. A good mechanic told me not to mess with the thermostat setting but I NEED more fuel at full load high rpm, and if I set the part load adjustment for that, it's way too rich at part load. No time for testing though big PCA race at Lime Rock next weekend :(

Also having problems getting it running on all 6 at startup, I have a fuel spraybar on the left side only, so that bank starts but the right bank won't fire unless I get some load on the engine by running on the street. Pops like mad.

Checked the CMA book - it has NO INFO about correlation adjustments! Says to check correleation, if OK leave it. If not OK, set middle bar to X mm and other bars for no preload. But NEVER tells you what to do to correct a wrong correlation! Looking at it I cant see how you can change the ratios that the stacks move vs the pump. If I could adjust correlation for leaner at small throttle and richer at large throttle openings I could do this without the protractors. PMOs are beckoning...

Your belt isn't a bit loose and slipping at high RPM is it? I found my pulley highly worn after it had apparantly run for some time without enough tension. This might explain the high rpm leaness?

Aren't AnalogMike's symptoms common for a stock MFI system mixed with an aftermarket "Low restriction" muffler? Basically the fuel requirement curve has been changed and the stock 3D spacecam doesn't adjust for it. Check out this thread for a fuller discription.

Hi Mike,

You are correct. The CMA doesn’t tell where zero degrees on the throttle valves are supposed to be, therefore leaving the two side push rods not accounted for as well. I think the definition of the zero degree is equally important as the 114 mm on the pump rod. Lee Rice states that you should turn the stop screw ¾ rev from fully closed. I think that may be too much. Question is how the stop screws on the TB’s where set from factory. Does anyone know???

Regards,
Carsten

Mike,

You are correct; CMA assumes you have good (or new) throttle bodies. Porsche doesn’t consider throttle bodies serviceable “in the field.” Of course we all know better. You can send throttle bodies out and have them rebuilt and recalibrated.

Matt brings up a good point. You have to go through the entire CMA before you focus on any one issue. All the mechanical pieces must be proper BEFORE you try and finesse the system. There can be almost no teeth on the pulleys and the belt will still run the pump. However the pump timing is constantly changing as the belt jumps the remaining teeth.

Carsten,
The factory, with all new parts, set the throttle body butterfly mechanically and then finessed it with air flow measurements on what we would call a flow bench. They then selected the best for California emissions cars, the better for USA and the others … well….
The issue here is these are not new parts. Many with worn (even slightly) tend to adjust the stops to reduce idle air flow (even though some of that air is coming past the throttle shafts.) Some push the limits with the throttle plate sticking in the bore. I’m not against adjusting but the critical issue is, as I said above:
1. The idle is proper on all six.
2. Every throttle butterfly and the pump lever come off proper idle at EXACTLY the same time.
3. The air and fuel maintain proper correlation throughout the full range.

With badly worn throttle bodies, the throttles start off in a non-original position. This has a progressive effect as they open compared to the pump setting. This is probably the most important thing you can detect with measuring the correlation. The problem is that you can’t correct it. The solution; rebuild or replace with new. Not small pocket change.

OK, off to the two side rods. The issue here is that the two throttle bodies do the same thing at the same time. Since the actuating levers all go across center, it is important that everything is the same side-to-side. An important aspect of correlation is that both #1 and #4 (and the others) do the same thing.

Over the years these engines have been worked on by some very creative mechanics. Some solved problems and actually made the MFI better. Others, …well…. Another reason for correlation is to find some hack repair attempt, mismatch of parts, or damage/wear that effects everything. I have seen a 2.2 throttle body on one side and a 2.4 on the other. Many times the wrong MFI pump. The ball linkage slotted to change the ratio. Fabricated linkage pieces and worse. A good test is to compare the big cross shaft with a known good one.

Best,
Grady

Hi Grady,

I have come to the same conclusion as well; if you have worn out TB’s you can forget to get it to run properly. My only problem is that I don’t know any places that can rebuild TB’s in my country (Denmark) or in Europe. I have 3 sets of used TBs. So I took the best set, and made new bushings for the throttle shafts. Had to take 0,5 mm (OD) of the shafts to make them round again. Very difficult if not impossible to get the shafts aligned perfectly in the bench. Have looked for replacement 8 mm shafts but without luck. Incorporated an O-ring to get the bushings airtight. The car runs if not perfect then just reasonable. Think I have come to a point of balance between part load adjustment and idle adjustment where further adjustment won’t help, because the “original throttle stop position “isn’t correct.

I would greatly appreciate if you Grady or any one else with a set of rebuild TB’s would measure the length of the two pushrods on your perfectly running motor for me. That must be the easiest way to establish the “original throttle stop position “. Or???

Regarding DIY on rebuilding the TB’s:
- Has anyone come across other more common TB’s or cabs, with 8 mm throttle shafts that might work in MFI TB’s?
- What would be a smart way to deal with the wear in the casting?? Would any one dare just to fill up the wear with some kind of “metal filler plastic padding”? Or is machining to a bigger OD with new plates the only option (it’s the best for sure I think…)?
- Where to get new throttle plates?

http://marinestore.co.uk/Merchant2/merchant.mvc?Screen=PROD&Product_Code=so-md35920&Category_Code=ppp


best regards,

Carsten

Carsten,

Throttle bodies are small and light weight. Have you considered shipping them to the States for rebuild? Bruce Anderson’s book lists this rebuilder:
Eurometrix http://www.eurometrix.ws/ “just across the Atlantic Sea.” You might e-mail them and ask about customs, etc. It is expensive but perhaps worth the effort.

Pelicans, what other rebuilders are there?

Best,
Grady

Eurometrix rebuilt mine a few years ago. Exellent work - they came back 'as new', great customer relations.