More fun with MFI and LM-1
 

HI,

I had my 2.7 RS engine rebuilt again after another missed shift at Watkins Glen. (Wevo is ready to install now!). We put in a lot of new parts and really messed up the pump calibration getting the new engine to run. So I got an Innovate LM-1 after reading all the threads about them on this forum.

We added headers so no more heat to the thermostat...
I pulled off the thermostat and made up a thumbscrew manual thermostat as shown on other threads, for now I have it screwed in all the way.

Engine is running pretty well now but it's a little weird... at part throttle, cruising around on the highway etc it's very rich about 10.5 : 1. Exhaust is very black. At full throttle, I logged some data through 3rd and 4th and into 5th gear and it got a little too lean at higher RPMS, 14 - 15.

I am wondering if anyone knows how the various adjustments ACTUALLY work - part load and thermostat adjustments.

1) Does part load adjustment change full throttle much?

2) Does the thermostat adjustment change full throttle more than the part load? If so, I can richen the thermostat adjustment and lean out the part-load.

Any other ideas?

THANKS!

http://members.rennlist.org/analogmike/04-03s.jpg

Innovate LM-1:

http://www.pelicanparts.com/catalog/shopcart/TOOL/POR_TOOL_CAT447_pg1.htm

-Wayne

Have you done the measurements and the geometry with the protractors on all the linkage?

Hi,

As far as I know and have experienced:

1) With the part load screw you adjust the pump main rack. Hence also the mixture at full throttle.
2) The thermostat is only for use at coldstart and warming up. When at full operating temp it should be max out all the time.
3) The relation between part load and the idle mixture adjustment seems to have a lot of influence on the 2500-3000 rpm range.

First make sure the throttle correlation is correct. If it is, then in your case I would properly try to give it 2 clicks counter clockwise (more rich) on the part load and two clicks counter clockwise on the idle mixture (lean).

Hope this helps.

Where in the exhaust have you positioned the O2 sensor?

Carsten

Another question that can have an impact -- what is the space cam in the MFI pump? Adding headers apparently often messes up the mixture on an MFI'd engine since the MFI cam doesn't take into account the extraction affects of the headers.

But if the engine was running fine previously, before you messed around with all sorts of stuff, I'd go back to the start of CMA and work through the process.

Mike,

What are all the components – cams, stacks, throttle bodies, heads, pump?
What headers? What do you have for mufflers – SuperTrap? Other?
How is your LM-1 sensor(s) mounted? Where?

Also, on your manual thermostat always carefully screw it in all the way but never firmly bottom it and back it off 1/16 turn or so. You don’t want to load the linkage. If you screw it in hard, you can bend the linkage.
With your LM-1 you can start backing the screw out and see where the thermostat action starts. The last ½ to ¼ turn should have the thermostat off.

John, Carsten, and Milt are right on.

You are going to have to set the main mixture for your proper WOT track use and adjust the idle mixture for best part throttle and idle. The part throttle probably will never be great without a stock OEM muffler.

Best,
Grady

HI,

THanks for the replies!

I already have the LM-1, purchased from Pelican Parts.

I have not done the protractor measurements, they were OK before but someone may have messed some up.

THe weird thing is that the right side of the engine is running much hotter than the left. I check with an Infrared pyrometer, at the fuel injectors (screwed into the heads) and the headers near the heads. The left side is coooler on all 3 cylinders... maybe the cross bar is off calibration.

Rims and tires - this is a combo that should not work, but works for me!
Turbo rear fuchs front and rear, front '76 930 8x15 with 225/45/15 and rear '86 930 9x16 with 245/45/16. Hoosier radials.


>> 3) The relation between part load and the idle mixture adjustment seems to have a lot of influence on the 2500-3000 rpm range.
First make sure the throttle correlation is correct. If it is, then in your case I would properly try to give it 2 clicks counter clockwise (more rich) on the part load and two clicks counter clockwise on the idle mixture (lean). <<

That is something I have not messed with much, could do the trick!!

this helps.

> Where in the exhaust have you positioned the O2 sensor?

the LM-1's sensor is on the driver's side collector on the header, on top.

I believe I have the correct 2.7RS space cam in the MFI pump.

> What are all the components – cams, stacks, throttle bodies, heads, pump?

All stock RS parts, but metal stacks from a 71S and K & K dual weber filters with no rain shield.

> What headers?

not sure, RSR style 1 5/8"

> What do you have for mufflers – SuperTrap? Other?

I was using a factory sport muffler for dialing on the street, will use megaphones for the Lime Rock Fall Vintage Festival in a week and may have to richen it up for that.


>> Also, on your manual thermostat always carefully screw it in all the way but never firmly bottom it and back it off 1/16 turn or so. You don’t want to load the linkage. If you screw it in hard, you can bend the linkage. <<

Thanks, I saw that in a previous post so I did that.

>> With your LM-1 you can start backing the screw out and see where the thermostat action starts. The last ½ to ¼ turn should have the thermostat off. <<

good idea.

>> You are going to have to set the main mixture for your proper WOT track use and adjust the idle mixture for best part throttle and idle. The part throttle probably will never be great without a stock OEM muffler. <<

I see, I will try to lean out the idle and richen up the part and try
to get it close enough. Actually only full throttle matters as it's a race car but I dont like the plugs getting fouled driving around and nice to be able to idle smoothly before the races to warm up.

Here is my engine last year, looks the same now except I painted a new fan yellow and no more thermostat or air ducts going to the heat exchangers.

http://members.rennlist.org/analogmike/myengines.jpg

thanks!

Mike,

Conda Green?

It is a big deal if the engine is running differently left-to-right. That should be your number one priority before you adjust anything else.
High on the list are the butterfly correlation and cam timing.

You have a situation where you should follow CMA and more.
Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf

I added some important stuff to CMA here:
“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
http://forums.pelicanparts.com/porsche-911-technical-forum/169445-mfi-thermostat-spacers.html

Don’t skip anything in the CMA and extension, no matter how sure you are.


I would recommend you get a second bung, O2 sensor and extension cable so you can monitor both banks. For your purposes it will be invaluable. Make some protection from rocks for both sensors. Make sure both sensors are in the relative same location in the headers.

You said the pump is 2.7RS. I assume that means it was recently rebuilt by a Bosch builder.
Do you have access to ALL the MFI tools and measuring instruments?

What P&Cs? How is the condition of the throttle bodies?


Cool 911.

Best,
Grady

Mike...welcome aboard....another Rennlist member defector ( or add'l member).

You'll find the guys on this board know their stuff and the ability to post to individual threads ( with Pics!) sure has Rennlist beat in the most of these areas....although John Dunkle is a great guy who has done much with that page.

Nice to see Kermit (?) in better shape following the Watkins Glen Excursion and such. Just missed seeing you again at the Glen during the Porsche clash in June...I was entering the grounds as you were trailering your car out !

Regards,
Wil

One of the reasons your car could be giving different readings from the left and right bank is Cam timing. I found that the right bank was leaner then the left. After mucking with the car for god knows how long, I decided to check cam timing. And it was off. Just a heads up.

Grady,

Thanks for the reply.

>> It is a big deal if the engine is running differently left-to-right. That should be your number one priority before you adjust anything else.
High on the list are the butterfly correlation and cam timing.

You have a situation where you should follow CMA and more.
Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf

I added some important stuff to CMA here:
“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
http://forums.pelicanparts.com/showthread.php?s=&threadid=169445

Don’t skip anything in the CMA and extension, no matter how sure you are. <<

I have the CMA but I think my mechanic adjusted the throttle body stops and it does not cover that :-(

All is OK up to the point in the CMA where I will try to balance the idle screws at 3000 RPMS. Will try that today and see if it helps.

>> Do you have access to ALL the MFI tools and measuring instruments? <<

I don't have the protractors or know how to attach them. But the linkages should be OK as they were not messed with.

My mechanic says the cam timing is right on, it only has 300 miles on the rebuild and he says the dyno numbers show that it must be correct. Dyno #s are VERY strong :-)

>> I would recommend you get a second bung, O2 sensor and extension cable so you can monitor both banks. For your purposes it will be invaluable. Make some protection from rocks for both sensors. Make sure both sensors are in the relative same location in the headers. <<

That would be a good idea.

>> You said the pump is 2.7RS. I assume that means it was recently rebuilt by a Bosch builder. <<

Not very recently, talked to Gus and he said it should be OK. Will try to clean one of the nozzles as you recommended in another thread, as one cylinder seems to be idling worse than the other 5.

> What P&Cs?

Brand new 2.7RS P&C and Cams.

> How is the condition of the throttle bodies?

Quite poor I think, but it's a race car so full throttle is main importance, and keeping the engine running OK during warmup to not foul the plugs is good enough.

I made a vaccuum retard connection to the middle left stack yesterday as the idle was too high and advanced. It pulled the timing back to TDC and idle speed is fine now. But the vaccuum actuator is banging a lot at idle as the vaccuum is not smooth, each revolution of the engine it bangs. I will try to attach a fuel filter or something in the vaccuum line as a small vaccuum reservoir to try to smooth out the pulses.

> Cool 911.

thanks!!

These are the cars I will be racing next week #8-0

http://www.analogman.com/911/lr02ving.jpg

Mike,

I will disagree; idle and part throttle are big issues with a race situation. How you beat that “big iron” is not on the straights but with finesse in the corners. That is where the great throttle response of Porsche’s MFI comes into play. The ability to modulate the throttle in the 0-10% and 5-60% range is critical. Full throttle is a no-brainer.

The MFI 911’s performance at the limit of traction is greatly enhanced by the very precise correspondence between accelerator pedal position and power delivered to the wheels. This is particularly true in a temporal sense; no hesitations.

You will need to pay particular attention to that mid-range, part-throttle mixture issue if you want to win.

I am concerned about your description of the throttle bodies. When you have been off the gas, braking into a corner, and need to have some power to control the car, you don’t want any hesitation or mixture difficulty. That is a mixture issue and the throttle body condition is a significant part of that at low throttle position.


There should be someone in your area with a Bosch nozzle tester. That is an easy (and inexpensive) test and can spot a potential problem without throwing money at new nozzles. BTW, I would test new nozzles and confirm the sealing, pattern, and opening pressure.

The throttle body idle stops are the first step in idle air flow measurements and correlation. You have the CMA, do you have the Factory Workshop Manual? Do you have access to protractors and air flow measuring?


As the saying goes; “The Devil is in the Details.” MFI has plenty of details.
I want you to embarrass that “iron” with your 911.
BTW, what are the other cars and who are the owners?

Best,
Grady

Howdy,

I found the right side throttle bodies were a little off, possibly from strapping my engine down inside my truck for transport. I balanced them and now it's pretty even on the air flow synchronizer.

I also leaned out the idle, idle is now steady and good mixture.
Full throttle is also good. But normal driving (just TOUCH the accelerator pedal on a 2.7RS in normal traffic or you will rear-end the car ahead of you or get a ticket) it is still running very very rich, about 10 - 11:1.

With 1/3rd throttle or more it gets fine. I guess this is a correlation problem. But I had the same problem last year early in the year UNTIL they changed over from winter gas to summer gas. Now, in CT, all gas has ethanol in it. I am thinking that my MFI does not work well with Ethanol. I may try to buy a barrel of gas in another state that does not subsidize the farmers...

anyone else have problems running ethanol laced gas with MFI?

have you tried disconnecting the dizzy vac ?

Ahhh...Analog Mike pays a visit.

Just to fill you guys in, Mike is a long time 911 owner, back when his first 911 was only a dozen years old! I think that Mike was the last guy to win the Solo II Nationals in A stock in a 911, in his case the "swimming blue pool" 72 (or 3?) 911S targa. Thats right, a targa! The kid could drive! Beat a solid field to!

His racing skill is very high as well. Clean smooth, and often wins, beating the big iron handily. Always a pleasure to watch. I look forward to seeing him at Lime Rock!

Hey Mike...is your mechanic as good as your body man?

Mike,

Sorry for not posting sooner. I’m still recovering from our little Colorado Pelican Technical Camping.

Sounds like you are getting closer.
Where does the mixture go rich? What is the idle mixture? Full throttle?

Adding an alcohol (ethanol, methanol) to the gasoline leans the mixture. Try it, you’ll like it.

If you have suspicions about fuel, many local drag strips sell spec fuel. There are independent fuel suppliers all over. Our local VP suppliers (4) sell 112 octane in 54 gal lots for about $230. They also sell in 5, 15, and 30 gal drums and deliver. They sell many octane ratings, leaded and unleaded.
Here is the VP site: http://www.vpracingfuels.com/vp_01_fuels.html?mgiToken=0C15B7C83F4F75C06#leaded

While the fuel issue is worthwhile to pursue, you need to complete the details of CMA first. Have you found access to protractors?

Is there still an exhaust manifold temperature difference left-to-right with your IR thermometer?

Best,
Grady

BTW, I like the 30 gal size drum (19” dia, 29” high.) Two strong men can pick up a full drum and set it in the back of a van or pickup. One person can handle it on the ground or ramp it into a trailer without any other equipment. A full 55 gal drum needs a drum dolly and a loading dock or lift gate.
Steel drums are the absolute best for storing, transporting, and dispensing fuel. You will need a proper bung wrench and a mechanical pump. Be very careful handling fuel.
G.

Hey Jake!

Thanks for the post and helping me out in the race today.
I couldn't quite pass that Ferrari 512S or Bobby Rahal or the other guy in the Chevron but beat all the production cars :)

http://www.motorenimages.com/photos/...rrari-512s.jpg


>> Sounds like you are getting closer.
Where does the mixture go rich? What is the idle mixture? Full throttle? <<

It is rich with no load and any throttle position, about 10:1.
With part load it is very rich, about 10:1 or 11:1 in normal driving.
At low idle it's not too bad, just very lumpy. At full throttle it's OK but a little lean. I fear the pump took a dump and needs a rebuild as their failure mode seems to be running rich like this.
Pump is leaking oil too, really needs help

I was going to try race gas but the LM-1 sensor might be destroyed by the lead :(


Still no protractors, will see if I can get an urgent rebuild on the pump before my big PCA race in 2 weeks.

>> Is there still an exhaust manifold temperature difference left-to-right with your IR thermometer? <<

It was improved a bit by balancing the air metering but I have
not checked recently, I should have done that.

Also installed a new Permatune I got on Ebay a day before the race, runs the same.

Yea....don't 'cha love when Bobby drops in in his little car? ;)

The video of you wasn't too bad. I'll make a copy and bring it up to the PCA race if I can make it.

Congrats on the drive...if I am not mistaken weren't all the 911s behind you running more displacement?? Good thing that Prescott Kelly guy got hung up behind the Pantera...your mirrors would have been pretty filled ! ;)

Mike-
The leaded race gas will shorten the life of the 02 sensor, but it will still work for quite awhile. The replacement sensors are fairly inexpensive so you can carry a spare for when it goes south.

TT

Mike,

The fuel suppliers offer unleaded fuel, including high octane to 109 octane. They also offer spec race fuel for SCCA (PCA, POC, vintage.)

Best,
Grady

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.