Today I just fitted new rotor arm, dist cap, new magnecor kv-85 plug leads.

Just have the (shorter) cables to the CD box from points & coil to go and should be ready to try to start.

Hopefully before the weekend I'll get it fired up.

One question ... Since I'll probably be running very rich until I get to that stage of CMA, and I'd hope to try the water decoking method, should I just clean & use the old spark plugs for now, or should I use the new ones and buy another set to change them later ?

Cheers.
Declan

Today I finished the wiring to points, coil & cd box.

I fitted the hot air supply to the mfi stat, did a quick double check I hadn't forgotten anything and turned the key.

cranked about 4 or 5 seconds, and sprang to life :)

(This is without the cold start solenoid connected.)

Then I remembered I hadn't opened the air bypass screws at all !

Is there a "start here" setting for the part-load & idle adjustments on the pump ?

Declan,

It's not that easy. The problem is the adjusters are screws-- one on the end of the main rack and the other on the end of the rotating assembly. See the MFI open heart surgery thread for pictures. http://forums.pelicanparts.com/porsche-911-technical-forum/386414-mfi-pump-open-heart-surgery.html?highlight=mfi

The main rack adjuster has twelve clicks per revolution. If you turn it one way, it gets tight and won't turn anymore. If you turn it the other way it comes out of the socket and falls off inside the MFI pump, causing you to mail the pump to Gus for repair. The idle speed has six clicks per revolution, same story.

I suppose you could call gus and he could tell you which way to turn the screws until they were at their stops, and then how many clicks off the stop to put them in the middle of the range. But the better approach is to dial toward the correct mixture setting, following the CMA procedure of setting part-load first and then idle, using an LM-1.

The reason it started without the cold-start is because the idle screws were closed! Too rich of a mixture. For the bigger engines, remember three half-turns from closed for an initial setting.

OK, John. I did read that open heart surgery thread. Very interesting.

I opened the bypass screws 3 half-turns and it still started without a problem without the cold-start !

I have an LM-1, so I'll try to tackle that next.

From the little running I did, it did sound as if it was missing on a cylinder, at random, so I must double check the plug leads are seated correctly (I found that very fiddly to get them seated properly)
Although it is obviously very very rich so it may simply be too rich to fire 100%.

Cheers.

Today I adjusted the timing to tdc @ 900rpm.

I couldnt get a smooth idle so knowing it was very rich (and I didn't have much time) I leaned the part-load by about 2 full turns, and got a lovely smooth idle so I could adjust the timing. (that did make it harder to start with no cold-start connected)

Timing was way off, about 11 degrees advanced.

Didn't get the 6k advance measured yet though.

Went for a quick spin a mile or 2 up and empty back road and its going better than ever !

By the time I got back, it had started lean popping, so I guess that means the stat is working :)

I have a couple of oil drips from the lower cam covers, and one upper cover so need to try tightening those & see if it will cure it.

Any competent Porsche driver tracks faster if brakes come smoothly.

Air filter, compression loss, plugs, dwell, timing, fuel pressure, injectors, belt, correlation, smog.

So where are you in the sequence? Seems like still investigating compression loss, I assume you checked the spark plugs, now you are working on dwell and timing? It's been a while since you listed off all the results of each diagnostic step of CMA.

I'm somewhere in the middle !

Air Filter : Clean.
Compression loss : Leakage & compression on #5 is pretty bad.
Plugs : new plugs, leads, cap & rotor arm.
Dwell : Not checked
Timing : reset today
Fuel pressure : Not checked*
Injectors : Not checked*
Belt : Not checked
Correlation : Set as per later method without protractors.
Smog : Not checked yet.

My next step is to check & set dwell and then reset timing

Fuel pressure : Don't know how to check this ? Must read up on it.

Injectors : Still trying to locate someone locally to test them. Anyone I've tried so far cannot test above 140psi. Local diesel guys not interested so far.

Declan, for fuel pressure instrumentation, see this thread, at the end I give suggestions for fabricating your own P233b.

http://forums.pelicanparts.com/porsche-911-technical-forum/391874-my-lucky-ebay-find-mfi-gurus-only.html?highlight=mfi+gurus

Injectors-- you are on the right track with the diesel guys, Koller & Schwemmer are in Germany and they are the Continental MFI experts, I have never dealt with them but Stijn VanDamme has, you may want to contact him. Certainly someone in UK has this experience even if you have to ring Francis Tuthill himself. . .

Belt-- you need an inspection mirror for this, any old mirror about 3x3" will do.

Smog. You will get there with the LM1, certainly.

This may help, it's not found in CMA but is contained in the factory 1969 service document. Gasoline is the most hazardous, flammable, dangerous, toxic substance commonly encountered-- always work outside so if the car burns the house doesn't burn with it.

http://forums.pelicanparts.com/uploa...1211325244.jpg

Thanks for the info John.

I have contacted Koller & Schwemmer by email, so we'll see if they can help with th einjectors.

Declan, I'm still lurking! If you get a reply from K & S it would be helpful to post their contact info here for future reference.

Declan,

I’m still lurking also. You are on the right CMA path.

Measuring the MFI fuel flow:
Read my prior posts on other threads.
I like to use a long hose back to the filler in the LF fender.

The issue with the fuel flow rate is detecting a restricted fuel filter screen fitting near the bottom of the fuel tank. In normal operation, the fuel is returned to the tank via a banjo fitting at the fule tank drain plug fitting. This is at the lowest point in the fuel tank. The returning fuel tends to ‘stir up’ any sludge and rust on the bottom and eventually suspend it in the fuel. As the car runs for a while, more collects on the screen filter causing a restriction and reducing the flow.

Perhaps the best test method is:
Run a long hose to the LF fender filler and do an initial flow test.
Reconnect the system as normal and let the electric pump circulate the fuel for a while.
Immediately repeat the flow test.

The immediate part is you want continuous flow thru the screen so the restrictions don’t fall off for the second test.

Best,
Grady

Got a bit sidetracked yesterday trying to source a fuel pressure gauge of some sort. Still haven't sorted that. (I eneded up trying to find an electrical pressure sender which I could then log using the lm1 & simply put a 5V meter on, but I'd still need a calibrated gauge to calibrate it from, so back to a simple mechanical gauge !)

I can only seem to find (easily) wither 15psi or 100psi gauges.
From reading other threads I believe 15psi is too low, so I'd need a 30/40psi gauge, considering they are not very accurate at bottom or at top of range

Thanks Grady for the input on fuel flow.

I presume I need to measure both flow and pressure ? Would a good flow rate suggest good pressure, or is it more complex than that ?

Thanks again.

Declan,

I actually did the same thing, I used a VDO electric pressure sender and cockpit series gauge so I could monitor fuel pressure while driving. It turns out that that information is almost completely useless while driving and I was never able to adequately correlate pressure fluctuations to low fuel and keep my eyes on the track at the same time. "What is this car, the freaking SPACE SHUTTLE?" I exclaimed, and removed the gauge along with about fifty feet of associated copper wiring.

Well, here is a nice ANALOG solution. The return hose that runs from the banjo fitting on the pump to the banjo fitting on the filter console has a 7mm inside diameter and 12mm outside diameter. I verified that with PET 999 180 030 50 AND our resident guru, Dr. Ing. Grady Clay, confirms it in this thread: http://forums.pelicanparts.com/porsche-911-technical-forum/202845-braided-fuel-hose-72t-mfi.html?highlight=mfi+fuel+lines

Anyway, I would source locally a piece of similar hose, a tee fitting that fits in the hose, and run another hose to the pressure gauge. You don't need to move the car with this setup installed, but all the connections must be tight and leak-free (see previous prophesies of doom regarding gasoline, etc.) Over here we would just source a fuel pressure adapter from one of the hotrod shops-- these accept a 1/8" NPT fuel pressure gauge of whatever range you want-- the trouble is that they have 3/8" hose barbs which are 9.5mm, this might be a stretch (Pun!) to fit into the hose. But here's an example of what I mean.

http://forums.pelicanparts.com/uploa...1211464298.jpg

This is probably easier than going the banjo route.

You need to measure both pressure AND flow-- a restriction downstream (or in the filter console) could give you adequate pressure but might limit the flow under load. What's really important about this step is what Grady mentions about making sure there's no stuff in the tank that gets stirred up. In the early days of CMA the cars were new and there was limited opportunity for rust in the tank, etc. These days all bets are off-- hence Grady's concept of CMA2-- updated for conditions you find 35 years down the line.

Declan,

Although interrelated, both fuel pressure and fuel flow rate are important, each in their own right.

Pressure is important in order to prevent cavitations at the inlet of the individual piston pumps for each cylinder under extreme conditions of temperature, load and rpm. The engine will run acceptably at modest rpm and cool temperatures with almost no fuel pressure. The point of 1 bar pressure is to insure full pressure at the performance limits and high temperature.

Flow function is two-fold. First is the electric pump circulating system must provide more fuel than the engine can possibly ever use. It is intended for there to be significant return flow at maximum engine consumption.

Second is the circulating fuel keeps the fuel section of the MFI pump cool. The oil section of the MFI pump is at engine oil temperature and is in direct contact with the fuel section (in fact it is all one casting).

The spec for the fuel pressure is 11.8 ± 3.0 psi (0.8 ± 0.2 bar) so a 15 psi gauge is right at the top limit of the spec range. You might inquire about the over pressure limit of a 15 psi gauge you buy. Many quality gauges will tolerate double full scale without damage. The only reason this might be an issue is if there is a MFI system overpressure malfunction (very unusual – I have never seen one). You might consider a ‘pre-test with a cheep 100 psi gauge.

I detect from your tool buying decisions that you want to accumulate all the ‘right’ tools to be able to maintain your MFI for the ‘long haul’. IMHO a good decision.


I like a large, easy to read gauge on a long hose. This way I can read the pressure in the cockpit while driving. If you fill the gauge and hose with some very lightweight engine oil and bleed out any air bubbles, the gauge will react more quickly and possibly uncover momentary loss of pressure otherwise not detected.

The port to tap on the fuel filter console is the one closest to the rear of the car. You can simply install a ‘tee’ fitting in the hose at the banjo fitting there. When reassembling after testing, make sure the fuel hoses are in ‘like new’ undamaged condition and have the proper Norma-Schellen (N-S) hose clamps.

Please be very careful with gasoline (petrol)! Use good clamps everywhere. Don’t tolerate even the slightest ‘seep’ of fuel … the car you save may be your 911 (this is a play on a US auto safety campaign in the 1950s “Drive carefully, the life you save may be your own.”

Best,
Grady

John, Grady,
Thanks for the info (yet again) :)

Regarding fitting an analog gauge, would it be a bad idea to do a permanent install of the pressure gauge in the engine bay somewhere ?

Any downside, apart form an extra 3 points of possible fuel leakage ?



Yes indeed.

I was "pretty sure" this car was a keeper; After a 5 minute drive the other night, I'm now 110% convinced & I can foresee multiple iterations of CMA in it's future. Hpefully next time it won't take me months to get this far !


Cheers.

I forgot to add... re the Norma-Schellen clamps for the fuel hoses ..What exactly do they look like ?

I found Norma-Schellen like this :
http://i24.photobucket.com/albums/c2...ard_5540_a.png

compared to what i know as "normal" hose clamps:
http://i24.photobucket.com/albums/c2...ose-clamps.jpg

Am I correct, (top pic) or are the correct Norma-Schellen clamps different again ?

"Be careful driving out there- the life you save could be mine."

Those were the final words on camera of James Dean, if I remember my trivia correctly.

http://i24.photobucket.com/albums/c2...ard_5540_a.png

Yes, these are the correct clamps for when you button everything up after testing.
Any clamp will do for the tests so long as your hoses aren't damaged and no leaks.

The 1 bar pressure is probably right at the service limit for these 'regular' hoses. Anything we can do to prevent a fuel leak may save the car someday.
The OE N-S clamps are one way.
Periodic hose replacement is another.

Best,
Grady

OK, Still no joy with a fuel pressure gauge, might have a lead, but will be a week or so before I can get hold of it.

I spent the last half an hour adjusting the dwell.
(Something I've never done before on any car ! Used to just set the points gap & that was it.)


I manged to get it from 26 deg to 39.5 deg*, but guess I'm just too ham-fisted to get any closer. There must be a knack to getting minute adjustments
.

My gauge reads in %, & 66.6% translates to around 39.5 degrees as far as I can tell.

So, dwell & timing set.

I got the LM-1 hooked up to make sure it was working & got around 12.8 at idle.

Must say it was much harder to start now without the cold-start hooked up !