Motor break in with MFI

[TargaT]

Hello All, I plan to fire up my freshly rebuilt 2.4T(73) motor in the next week or 2. Although I am new to MFI I have read enough to know I could run into a rich situation which is probably not good at break in.
Can anybody recommend a process that I can follow when starting to avoid any possible issues relating to MFI. ie
- how should I start the motor
- any basic pre start checks for the MFI to ensure things are functioning properly
- should I disable certain funcions?
I expect the air temps to be around 50F. I have had the pump checked and cal'd ,new injectors. So far I have installed the throttle bodies and set the throttle plates and linkages per CMA. Throttle bodies have been thoroughly cleaned including all air passages. Plan to have the stacks and rest of the linkage installed this weekend along with new fuel lines etc.

Any guidance would be greatly appreciated as I have several hundred hours in this motor along with way too much money

Thanks, Joe

[304065]

Joe,

Set the twelve-click adjuster in the middle, and the six-click adjuster in the middle and go for it. Try to avoid running a lot of fuel into the base of the intake stacks for the cold-start system. Start with the air bleed screws five-halfs open (2-1/2 turns from stop). Make sure the thermostat hose is connected and working properly. When then engine starts the thermostat will be cold and the pump will be set rich. It will run rich for a few minutes until the metal discs heat up and move the operating rod. If you want to avoid that, soak the thermostat housing with a heat gun for a few minutes before you start the engine. You might avoid a ton of fuel being dumped into the cylinders when you start, although a certain amount will be inevitable.

Others much more knowledgable than I are present here. . .

[svandamme]

do disconnect the cold start injectors, they can flood the engine in no time, and can cause major headaches if your engine doesn't start straight away...

simply pull the electrical wire from teh solenoid on top of the fuel filter... should do the trick

as for starting up the engine itself
i had mine spin around without spark plugs , the engine will spin very fast, and build oil pressure, once you see pressure on the gauge... put in the plugs, and fire it up...

[Grady Clay]

Very good question.

The basic issue is you want it to start and run smoothly the first time you want it to start. That requires the ignition to be in proper timing and functioning correctly. That means the fuel system is ready to work as intended.

The distributor can be independently run in on a distributor machine. This lets the points to get settled in, any excess lube removed, the advance mechanism checked and measured. Knowing the exact relationship between the static timing and the advance at 3000 distributor RPM allows you to accurately set the timing statically when assembling the engine. No need to check it at 6000 engine RPM – yet. Every little detail of the ignition system should be repeatedly checked – no incorrect firing order, loose or corroded connections. Even patients when you finally install the sparkplugs to insure the plug connectors are on the plugs will pay off.

With a long term project like this, you should pay attention to the condition of the fuel, fuel tank, electric pump and filter. Clearly you should install fresh high octane fuel. The reason for the octane is the assembly lube and oil from unseated rings reduces the octane rating of the air-fuel-oil mixture significantly. This is not the time to tolerate any detonation. This is particularly true with high compression.

It is not unusual to find the filter screen in the tank fitting clogged – if not at start then soon after as the 911 is driven and sediment is disturbed. A through tank cleaning is worthwhile and removing the filter screen for cleaning and inspection. Unless there is other indication, I prefer to change the main fuel filter at the first service. That way the old one has collected the majority of the storage and assembly debris. While the engine is out you should connect the fuel lines together where they normally connect to the MFI pump and circulate the fresh fuel. This will take some jury-rigging so be careful. Disconnect the CDI and be careful with exposes wires at the starter location. Do this outside and check for fuel leaks.

Remember to fill the MFI pimp with engine oil before you install it on the engine. Does the pump turn smoothly by hand? Make sure you have the pump timed correctly. It is easy when out of the car. Check that nothing has slipped down under the pump.

Are all the MFI linkages free to be adjusted but now tight?

When the engine goes in, have fresh new batteries with clean connections and ground straps (including at the transmission). Still have the CDI disconnected (make yourself a little paint mark on the connector so you can connect it easily (you can’t see the orientation when the engine is in.) Make sure ALL the electrical connections are proper and tight. Did the alternator ground strap get reinstalled? No shaky connectors from handling? No damaged insulation?

I’m assuming you didn’t have the electrics relay panel, CDI or fuel console out.

I agree with Stijn, disconnect the wire to the cold start solenoid on top of the fuel filter console. It should start just fine with only the cold running enrichment thermostat.

You want to start it with the air filter assembly off the engine so you can see, hear and smell down the stacks. Check for any errant hardware on the butterflies. Is the engine firewall sound pad not going to fall in the intakes?

Are you ready to crank the engine? Throttle linkage free and properly operates from the engine and pedal? Nothing to obstruct the return to idle? All fuel lines not leaking? Oil in the system? Oil filter in place? No shop towels in the breather? Big CO2 fire extinguishers handy? Out of doors? Not in gear and with parking brake on and wheels chocked?

Turn the engine over at least twice by hand with the plugs out. With the fuel pump running (but the CDI still disconnected) crank the engine for oil pressure. I would do this several times waiting 5 minutes or so between. Eventually you will start to smell fuel in the stacks (you may even start to hear the “chirp” of the new high pressure nozzles.) That means you have filled the steel lines to the nozzles (it won’t start otherwise.) Check for fuel leaks at the nozzles and on top of the MFI pump. While cranking, note that the fan belt outer pulley is on straight.

Stop and think about checking everything again. Is everything tight? (A general rule is something is either off or it is installed and tight – never on finger tight.)

Find Z1 for #1 cylinder and position the engine say 45 degrees prior. Connect the CDI. Attach the coil wire to a grounded spark plug. Be very careful here because you now have fuel and ignition. If you smell gas, let the fumes dissipate. With the ignition on, rotate the engine CW and confirm spark near Z1 remembering your distributor testing. If the distributor clamp tight?

With the key off, install the sparkplugs. Make sure the plug connectors are on correctly, the cap is seated and one final check of ignition wiring firing order.

Ready for lift off!

When it fires, let it run at a speed where it runs smoothly – somewhere in the 1500-3000 RPM range. Immediately check oil pressure, look for oil or fuel leaks and listen for anything unusual. Check to see that the thermostat is getting hot. Check oil level as it warms. As the thermostat turns off you will have some popping in the intakes as it leans the mixture.

Check the idle. If it won’t idle, just use the hand throttle for now. Unless it absolutely won’t run reasonably, don’t adjust anything now. Asap you should carefully drive it keeping the RPM in the 2-3500 RPM range. Make the trips short and let it cool between trips. Gradually extend the trips, increasing the amount of throttle and RPM as you confirm everything is working OK. Check the static timing and at idle to confirm it hasn’t changed. During the break-in period you eventually will get to short bursts of 6000 RPM and full throttle (you are going to need to check the ignition timing at 6000 eventually.)


The first maintenance is very important and comprehensive. You want to measure the cranking compression and cylinder leakage, adjust the valves, torque the heads & rocker arm shafts and check pump timing and belt tension. This is a start on a complete CMA before you adjust anything.

Part of this first maintenance is to re-torque the CV bolts.




This is one of the few times I’ll disagree with John. If the pump was calibrated, don’t change the adjustments – yet. Yes, it is OK to see how many “clicks” it is from “in” just get it back to where it was set. Don’t move the adjustments too far in the CCW direction (2 turns max) as it is possible to unscrew them.


For those planning a maintenance overhaul it is very worthwhile getting the engine in the best state of tune possible prior to disassembly. You can see the advantage of knowing that all the systems are properly functioning and the overhaul and initial running only has to deal with the machinery.

Another little trick is to use an old muffler for start-up so all the oil and assembly lube ends up there and not in your clean muffler that you intend to use for MFI fine tuning.

Best,
Grady

[pwd72s]

Guys, I've known Grady for decades. Yet his knowledge never ceases to amaze me.

[Zeke]

Originally posted by pwd72s
Guys, I've known Grady for decades. Yet his knowledge never ceases to amaze me.

Indeed. That is the most comprehensive treatise I have ever read on initial start up of a new engine. I have a few books, but a print out of this thread will be in between them for future reference.

[TargaT]

My sincerest thanks to the board and especially Grady. This goes a long way in boosting my confidence level. Now lets just hope I did everything well on the inside. I will keep you all posted. I don't have the most recent pictures but here are a few.

Thanks, Joe

[TargaT]

[pwd72s]

We're pulling for you Joe. May the start go well, and may you enjoy many miles with the rebuilt engine.

[304065]

Grady, outstanding post.

I overlooked where the gentleman mentioned he had the pump calibrated-- my thought was, if for whatever reason the adjusters had been turned all the way one way or another, it wouldnt' be good to start with them full rich-- or lean. But if the pump's been set up, I agree, no touchie!

[Grady Clay]

Joe,

Beautiful engine, great workmanship, I’m sure it will work great for the next 33 years! Give yourself a pat on the back. You are nearing successful completion of many Porsche owners dream. Work hard to attend to every little detail – nothing is too small or unimportant. Whatever you do, don’t now get in a hurry. If there is some issue to attend to – do it now and don’t postpone to “later.”

When I write one of these it is intended to answer your questions and additionally allow others contemplating this to see all the detail necessary. When I state the obvious it may be for that purpose.

Most threads focus on assembling the mechanical parts of the engine. Let’s here focus on all the ancillary parts, the start-up through the first maintenance and CMA. Just what you are doing now.

Please keep posting images. I’ll critique them and edit my post. I could make it 4X as long and still not cover everything but then few would read and study it. Much of answering your questions are part of CMA2. The start-up procedure for an engine/911 that has been sitting or stored is far more delicate because of the lack of assembly lube and the possibility of corrosion on important parts.


It would be wonderful if you can post everything found, done and replaced in your engine. Everyone here will appreciate the details.


OK, on to your images ….
First Image:
What did you use to clean the case?
What cylinders are those?
I trust those are new chain ramps.
Test fit the nozzles in the heads with the engine upside down so nothing gets dislodged and falls into a cylinder. Install the nozzles so they spin in easily with AntiSieze. When you go to connect the pipes to the MFI pump and nozzles, grease between the nut and the pipe and AntiSieze the threads.
What is your intended use? If you plan to install a rear tow hook/jack point, now is the time to install longer bottom two engine mount studs.


Second Image:
Are these two different throttle bodies or just during cleaning?
How did you clean them? You will want to coat the bare magnesium to prevent corrosion. This is particularly true where the washer is to hold it to the head. Use a new plated washer.
Lube all the threads on every piece of linkage, stop, lock nut, etc. First you want them to be easily adjustable. Most important, your beautifully clean parts can corrode very rapidly.
Assemble the linkage with very light lube (WD-40) and then fill each ball cup with grease after you have final adjustment after the first maintenance.
Don’t use screw-type hose clamps on the fuel, cold start or vacuum hoses. Use only OEM Norma-Schellen (N-S) clamps of the proper size.


Keep the images coming. Since I’m doing this from 35+ year memory, that will help me.

Best,
Grady

[pwd72s]

This thread is a huge opportunity for us all...Joe, having Grady offer help and expertise?...it's a great gift!

[TargaT]

Thanks, for the additional advice. Pictures yes I have tons of detailed ones. I've taken photos every step of the way on disassembly and assembly. If I had the time or know how I'd put them on a website so people could access them.
The car was purchased about a year ago (73T targa). It was running very poorly and had a multitude of oil leaks. Some the MFI hoses were missing. I figured with all the effort of tracking down all the oil leaks and the compression being borderline it was best to go all the way.
I had a lot of ideas for this motor but in the end I believed the best thing to do was put it back completely stock. After all this is one of the reasons I bought the car, it was completely stock and unaltered. Besides the car was extremely solid. In the end modifying it would cost me more$ and I believe the car would be worth less. I'm glad I went this route.

The cylinders are stock cast which were blasted and painted. Oven baked while the wifey was out. They turned out great. The photo of the throttle bodies is a before/after. All the passages were completely blocked. I'm surprised this thing ran at all.

A couple of more photos

Joe

[pwd72s]

Joe? Grady will blush because I'm posting this...but IMHO, his shop in Denver was the model for ANDIAL. He's offering one HELL of a gift here. I'd advise you to take him up on it... Grady kicked ass over everybody, including factory wrenches, @ PCA Parade tech quiz contests back when early 911's were the only 911's. Historians here are more than welcome to check PCA parade records. Paul

[TargaT]

Hey, everytime I get near that motor I thank God for the internet, this forum and people like you and Grady.
Don't worry I plan to take all the help I can get. Next time I find myself in Colorado I will track Grady down and buy him a nice dinner.
Now back to business. I just installed my stacks and connected all my linkages. I thought I did a good job of setting up the throttle plates. Lifted them all off about the same distance from closed. What I'm finding though is when I connect the throttle valve pushrod (#4 on diagram)on the left side I am opening the right side considerably, so they are obviously not working in sync.
I measure both and they are identical at 149.5 mm. When I set my throttle plates I did have to adjust some of the connecting rods. When I measure them they vary by maximum 3mm.

What should I adjust to get the left and right side in sync.

thanks, joe

[pwd72s]

Bump...hoping Grady weighs in. Good question Joe, but since I've never done this, I don't have a clue. Have you read the MFI tech info of this site? "Check, measure, adjust" is the biggie...here's a link:
http://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

[Grady Clay]

Nice Targa!

“I just installed my stacks and connected all my linkages. I thought I did a good job of setting up the throttle plates. Lifted them all off about the same distance from closed. What I'm finding though is when I connect the throttle valve pushrod (#4 on diagram) on the left side I am opening the right side considerably, so they are obviously not working in sync.
I measure both and they are identical at 149.5 mm. When I set my throttle plates I did have to adjust some of the connecting rods. When I measure them they vary by maximum 3mm.
What should I adjust to get the left and right side in sync?”

Since you have had the throttle bodies semi-apart (moved the stops, cleaned the air passages, adjusted the links) you sorta need to start from the beginning. It would be ideal if you could have them professionally set up. Baring that solution; the vacuum (cleaner) flow bench is your next choice. There have been several good threads about this but I don’t have the link at hand.

The crux is to set the air flow the same on all six throttles while off the engine. Try and get them even with all the air bypass screws about 1-2 half turns out (CMA calls for 3 half turns on new throttle bodies.) Err on the side of too little air flow.

When you install them on the engine all six are on their stops. You then start installing links starting with one from a middle throttle to an end throttle. The links should take very minor adjustment to have an end throttle come off its stop when the center one does. Use very light lube and actuate the center throttle via the link to the cross shaft. Once you are done all six should come off their stops simultaneously when actuated by the main throttle rod that goes forward to the accelerator linkage.

Now it is time to install the pump rod set to the correct length (114 +/-0.2 mm). Do this with the links to the two throttle bodies disconnected and the microswitch backed off. You want the linkage to stay where the pump is still on the idle stop (pump lever all the way lean – to the rear of the car.) If the linkage wants to actuate the pump lever, find out why and fix it.

You should be able to reconnect the rods to the throttles without opening them off the throttle stops. If not, adjust those two rods so the pump and both throttle bodies come off the stops simultaneously. CMA allows for a maximum difference of 5 mm L-R. You can take off the left arm from the cross shaft and usually get both L&R rods the same length.

Now is the time to borrow the Correlation Protractors, P228b & P228c (you need both.) The CMA procedure is pretty good here.

The idle will probably be too high after the engine has a few hours on it. You may have to repeat this entire process – just now on a running engine. If the idle is too low, you can simply use the hand throttle.

Now would be a good time to check all the throttle linkage in the chassis. Check Here Everything should be cleaned and lubed and the plastic bushings replaced and the new ones lubed. The common places needing attention are: The accelerator pedal hinge, remove the pedal and get some oil back under the rubber covering at the mounting bolt holes to lube the hinge. Install new bolts with AntiSieze.
The little bell-crank at the pedal assembly can contact the sheet metal of the tunnel, “adjust” the sheet metal if necessary. It isn’t uncommon for the joint in that link to fail, inspect carefully.
Check that the plastic throttle stop in the floorboard is easily adjustable.
Confirm that the hand throttle stop is tightly clamped on the throttle rod. You can adjust the retaining friction on the hand throttle by adjusting the through bolt.
A common old-age failure is the accelerator cushion, it is worthwhile summarily replacing. The proximate cause of failure is usually incorrect adjustment on the accelerator pedal stop. Check this link.
The bell crank at the transmission, the link linkage piece to the engine need attention. Replace the plastic bushings at the #3 cylinder accelerator bell crank – that is very difficult when everything is assembled and in the car.

Before you start the engine you want to check that all the accelerator linkage os free and can’t possibly stick open. Set the limit of travel of the accelerator pedal to where the throttles are almost full open. You should be able to hold the pedal hard against the stop and still move the linkage at the engine slightly open further. That last bit means nothing to performance but if you use the stops at the engine things will get damaged.



On to Image three:
What was the condition of the MFI pump drive belt and tooth pulleys? They should be replaces as a set on three as one slightly worn pulley will ruin a new belt and damage the other pulley.
The pressure host to the MFI pump is a common source of oil leaks.
I assume you replaced the paper/alu heater tubes with new OEM.
Is/was your car with A/C?
How are the heat exchangers? The left one is particularly important for proper MFI operation. The left one looks like a ’72 and not a ’73 in this view.


Image four:
Judging by all the oil and “agricultural material” the engine should cool dramatically better.
What did you have done to the case?
It appears to be a virgin, is there any sign anyone had been into part of it prior?



When you connect the oil hose to the back side of the oil filter consol, pay particular attention to cleaning the threads. You should install it with grease between the nut and hose fitting and AntiSieze on the threads.

Did you have the oil tank out for cleaning? Carefully inspect the inside of the tank for rust or other debris. There isn’t any filter protection between the inside of the tank and your nice new bearings. Cleanliness is paramount.


” The cylinders are stock cast which were blasted and painted. Oven baked while the wifey was out.”
For the record, I’m not in favor of painting cylinder fins. It does slightly reduce the heat transfer from the cylinder to the air. In this case it probably won’t hurt anything.

Keep the pictures coming. If you have all the images in one file, can you burn a CD and let me edit them for you?

Best,
Grady

[304065]

I'm going to stand corrected by the Maestro AGAIN, I said five half-turns, five-half turns is correct only for a 2.0-2.2, three half-turns is correct for a 2.4, CMA p.22! Bravo, Grady!

This thread is getting printed out and going in the MFI looseleaf.

By the by, the CMA you can download from Wayne's site is fuzzy. Do a search under Derek Murray's name, and download the clear version from his signature. With the orginal version you will think you have had one too many Spaten Optimators when you read it.

[TargaT]

Hi Guys, I managed to get the right and left working in sync by lengthening the left push rod slightly. The differential between left and right is 3mm. I suspect this was affected by me rebuilding the throttle bodies. I actually had all the butterflies and shafts out. The shafts and bushing were all really tight so it was just a very thorough clean and lube and reassemble. From what I can see through the stacks, at full throttle all the butterflies seem to be straight up and down. So from a static perspective I'm feeling pretty good about the setup.
Also replaced all the fuel lines on the engine today with OEM stye braided line and proper clamps , nice crimp clamps on the cold start lines.
I replaced the MFI belt but not the gears, they looked to be in good shape. New SSIs are currently on order and I do have new heat exchanger tubing. What I have not gotten yet is the smaller diameter tube that runs to the MFI pump. from the engine tin. Do I get this at the dealer? As wel,l is that what goes on the underside of the engine tin?Mine was missing and how long is this piece?
I don't believe this case was ever apart,although it may have had some minor head work done at one time. Evidence was one of the cam sprockets was on backwards. The chain was rubbing pretty badly on the inside of one of the cam boxes (see photo). Makes me wonder how critical chain alignment is when this car ran in this state for so long.
The car was an original 80K car but I believe the motor's premature wear was due to lack of proper maintenance and poorly functioning MFI. I believe the car was running in rich mode the last 10-20 years.
The previous owner who had the car the last 25 years got the car as a debt repayment from a bankrupt brother in law. He wasn't much of a car guy and basically changed the oil once a year drove the car a few times and threw it back in the barn.
If you don't mind a couple of more questions please.

- the fuel filter I got has a different (much smaller) spigot on the bottom than the original. Do I have the wrong one? My parts guy tell me this is the only one available
- 2 of the fuel lines off the electric pump that go rubber/metal/rubber, the ones that go through the chassis. How do you feel about one solid rubber line. I don't like the look of my metal sections. Is the main reason the risk of abrasion through the chassis?

I'm hoping to have this puppy installed 2 weeks from now. Moving kinda slow cause in parallel I'm installing the rear suspension. Had all the pieces blasted and powder coated. All new bushings, bearings, shocks and brakes.

Thanks, Joe

[TargaT]

bump