Finally getting around to CMA on my MFI

[declang]

Houston, we have a problem.


Right, I've hit my first problem, I think.

I was so happy with the leakage figure of 5% or 6% on #4, I got brave and tested #5

240 degrees clockwise rotation from #4, visually checked where cams are, should be rocking, looks right, checked inlet valve clearance - bit tight, but should be OK.

Took out plug, put in hose form leakage gauge, setup & zeroed leakage gauge, plugged in hose from plug hole ... 45% leakage.

Damn and blast... or words to that effect.


I turned a few revs, and got rocking again on #5, (inlet rocking, visually seeing exhaust off lobe, matching a 120degree mark on pulley). same thing. 45% leakage.

I haven't checked exhaust valve clearance.

I'm thinking I have a problem.

I didn't bother moving onto next cylinder

[Grady Clay]

First, check ALL the cylinders.
Do a ‘cranking compression test’ also.
Repeat your #5 cylinder test, noting where the air is escaping.


Now may be the time for what the Ferrari guys call an “Italian Tune-up”:

Find some place where you can drive extended up-hill under full throttle, high rpm and high speed – safely.
Repeat several times.
Re-rest the cylinder leak and cranking compression tests.

Best,
Grady

[304065]

Declan,

Be absolutely certain that the #5 piston is actually at TDC on the compression stroke on that cylinder.

The way you can do this is: start just ahead of TDC, connect the air, you should see 80% leakdown because the intake valve is open. Then rotate the engine until you see the needle flip and you feel the engine push back, keep turning until the mark on the pulley lines up with the notch in the blower housing-- THAT is TDC. Read the gauge. Still 45%?

If so, then follow Grady's instructions to the letter and see if it helps. If not, then prepare for extreme de-coking using seafoam or water.

A related, relevant question is, WHERE is the leakage coming from? Intake, exhaust or crankcase breather? A rubber glove, like the ones you wear when working on the car to protect your hands from nasty Volatile Organic Solvents, can be stretched over the intake funnel on #5, the exhaust pipe, or with a rubber band, the breather outlet on the case. The air has to go somewhere assuming it's not leaking out the spark plug hole.

This has happened to me several times and invariably it's something other than a bent valve, it's operator error or a piece of carbon or something. (Someday it will be my turn. . . )

[declang]

Grady, John,
Thanks for the suggestions.

I did crank up the pressure to about 4 bar and could hear the air leaking, but don't know where from.

I'm waiting on delivery of the gaskets from our host to get the throttle bodies & stacks back on, so can't do the italian tune up yet.
I'm also waiting on delivery of a compression gauage, so can't test that yet.

Hopefully I'll find half an hour this evening to test again.

Thanks for the input & I'll post my findings later.

[declang]

Update.
I leakage tested #4, #5 and #6 again

#4 = 5%
#5 = 50%
#6 = 5% **

** When I started on #6, I had about 60%, found it was the intake valve, and a light tap on the the rocker arm sorted it.

I used the "glove on the exhaust pipe" method and found #5 is exhaust leakage.
I haven't checked any of the exhaust valve clearances yet.

I went through them again in case the inlet valve was sticking on #6 but I got the same 5% figure again.

I'm now thinking the problem with #5 might be carbon stopping the exhaust valve seating properly, or am I just hoping ?

Must admit I nearly paniced when I got 60% on #6 to start with !

Cheers.

[304065]

Declan, you very well could have a burned exhaust valve on #5. Or you could have a piece of carbon blocking the valve from closing, could have fallen off the head or piston and be lodged in the bottom, gravity being what it is.

Did this engine run well before this exercise? Before tearing it down I would look inside #5 with a borescope or pull off the starboard heat exchanger and have a look at the valve (easy enough to do) to verify that things, in fact, HAD gone horribly afoul.

Once you get it running the picture will get clearer.

[declang]

John,
This engine ran very well when warm.

I started down the CMA route as it was very very rich, especially when cold.

I've never driven another MFI car, so cant compare, but it would blow the socks off a basic 2.7 CIS I've driven, so I thought it was going well.


Cheers.
Declan

[declang]

Update:
I've checked all cylinders for leakage now, and have :

#1 = 5%
#2 = 9%
#3 = 5%
#4 = 5%
#5 = 50%
#6 = 5%

#2 : Can't find where the leakage is. I did crank up the pressure to about 6 bar and listened. I can hear it, but cant find it ! I still have the glove on exhaust, but its not inflating at all. I tried putting a glove on the inlet port, and think I got it held in place, but no evidence of leakage there.
Sound seems to be coming from under the air shroud somewhere, but I cant pinpoint it.

#5 : is exhaust. still haven't done any further investigation.


I now have a compression gauge.

I presume "cranking compression" is the compression I get while cranking the engine, not running/idling ?

[Flieger]

Could a broken/loose/pulled head stud have caused the head to loosen and slap the top of the cylinder? Maybe the mating seal is worn and allowing air out.

Excuse me for lurking before posting only now.

[declang]

Originally Posted by Flieger

Excuse me for lurking before posting only now.

No problem ... I welcome any and all suggestions !

[declang]

How do I do a compression test ?
I presume it's "cranking compression" I need to check, but I'm unsure what I need to do.

I have the electrical panel with the CD box out of the car.
I have all the pipes off the injectors

Should I simply take out the fuse for the fuel pump, and turn the engine using the starter motor, or is there more to it than that ?

I have a sealey compression gauge CT955



I have it fitted to the spark plug hole & get compression while turning the engine by hand.

[declang]

Today I finally got my package from our sponsor. (I think it got routed through the UK, so it took aaaages), so I now have dial gauge & z-block, the gaskets for throttle bodies & stacks, new cam cover gasket kit, new dist. cap & rotor arm, etc.

First off, I guess I should measure the cams & see what I've got.
Can I measure exhaust cam from the top also, or do I have to do that from underneath ?

Thanks.

Edit:
OK, I got the z-block & dial gauge setup with dial gauge on the inlet valve "collar"
I measured 10.7mm. I thought I should see around 5.4mm .. or am I missing some logic here, and (5.4 * 2) = 10.8 ?

Help !!

[declang]

I've checked all valve clearances now, and they are all set. very minor adjustment on a couple of exhaust valves, others were all perfect.

While I was down there, I noticed both case halves are stamped with 7R

From memory..
901 101 101 7R
901 101 102 7R

Also I noticed stainless heat exchangers, which I didn't know I had !

When I dropped the oil, I was amazed how much like petrol it smelled & I've only done about 150 miles maximum since I changed it !

So, I'm a bit stuck right now:

How & where to measure the cams using the dial gauge & z-block. I want to do this while I have the cam covers off, & access to inlet section is great without the TB's & stacks in place.

Declan

[declang]

update :
My dial gauge is only 10mm travel, so I'm now waiting on delivery of a 25mm gauge.

Full deflection seems to be 10.7mm, so I still haven't measured the valve lift correctly !

[declang]

OK, After ordering a 25mm dial guage today, I was searching on here for any specs on valve lift values to check against, and found the link to drcamshafts.com.

That shows the early S cam as:
inlet : 0.455" = 11.56mm
exhaust : 0.399" = 10.135mm

I also spotted the "setting" column as 5.0-5.4mm and that rang a bell from an earlier post in this thread, so I read back to see.

Yes, Grady explained about measuring valve lift at overlap which I totally ignored !

I have been measuring (trying to measure) the total valve lift, hence my needing the bigger gauge.

(I was silently cursing Wayne for selling me a 10mm dial gauge when I obviously needed a longer travel, but now it makes sense ! Sorry Wayne !)

So, that's this evening's work planned. Measure the valve lift at TDC overlap.

[declang]

Inlet valve lift at TDC overlap is 5.2mm **

I haven't figured out yet how to meaure the exhaust valve using the 10mm gauge !

I should have a 25mm gauge soon, so will get more accurate readings on the valve lift & should be able to measure the exhaust valve at overlap also.

** I presume TDC overlap is one crankshaft turn (360*) from TDC Compression ?
It's the only way I can think of to get both valves open at the same time.


I also finished assembling the throttle bodies with the connecting arms between the butterflies and still have good equal airflow. I followed the recommendation above about assembling without grease, checking airflow & then assembling with grease & checking again. All good


I started to refit the electrical panel (with the CD box) but I need to shorten the mad cable assembly I had from CD to coil & points.

Where should these 2 screend cables be routed ?

I've searched for pics of MFI engine bays, but haven't come up with anything thats shows the cable routing.


Thanks,
Declan

[declang]

feels like I'm talking to myself here for the last while .. should I start a new thread, or keep posting here ?

Anyway, Today I refitted the throttle bodies.

Nobody told me how difficult it would be to remove old gaskets. I think it took me 2 hours of poking & scraping, stuffing rags into the inlet ports, vacuaming the pieces out, spraying with WD40 to soften the paper that was left, scraping and scraping, etc etc.

At least its done now, just need to torque the nuts.

I got some stainless nuts & stainless wave washers. I presume thats OK ?

What torque do I need on these, or is is just "damn tight"

Next step will be the stacks .. Should I use wave washers or flat washers for those, and what torque should I use on those ?

Thanks,
Declan

[304065]

Declan,

We are still here, listening intently for the results of that cylinder.

Stainless is fine from a corrosion standpoint but remember that stainless can gall against the steel studs so be sure to use some sort of antiseize when you reassemble. Old zinc-plated nuts would be fine.

What dimension across the flats (ATF) or if you prefer German, Schlusselweite (SW) of nut are you using on the stacks? I prefer an M8 SW 12 so you can get a 12mm swivel socket on it. This is one of those sockets that looks like a universal but instead of having a 3/8" square drive on both ends, it has a 3/8" female on one end and the 12mm socket on the other. Makes it easy to get on the nuts. Anyway, it's not hard to find M8 SW 12 even though the 13mm type are more common in hardware stores.

Wave washers are correct, these don't do much to maintain the torque of the fastener, they are really to protect the magnesium from damage by the nuts. There's no torque specfied in the factory literature so in this case we look at the torque of of every OTHER M8 fastener in the car for which a torque is specified, and it turns out to be 25NM (18.4 foot-pounds). So that's a good torque to use. That isn't very much torque at all, by the way. The fact that you are compressing a paper gasket should affect things, but I would go easy on it-- you do NOT want to crack the ears off the throttle bodies, they are old, brittle magnesium and this is easy to do.

The stacks are little teeny M6 studs with 10mm ATF nuts. These should get a torque of 11NM (8.1 foot-pounds). You can break these as easily as breathing on them, so stay away from the 24" breaker bar and just use a little toolkit wrench to snug them up. Again, there are paper gaskets to compress but it shouldn't take much, you just want to eliminate air leaks.

Obviously you should use no gasket sealant of any kind, they seal just fine without it and avoiding the sticky mess or horrors of RTV is a step up the wheel of Porsche Karma.

The reason nobody told you how hard working with MFI was is because if we told you, you would trade in your 911 on a used Fiat Panda, become a strict vegeterian, begin wearing cork-soled sandals and answer every question with a question. Far better that you cuss, swear, bleed, sweat and puzzle on the road to MFI triumph: the chainsaw-like howling of the flat six flat-out at wide-open throttle under load, baying like the hounds of hell in some macabre Wagnerian anvil chorus, has NEVER been heard by the owner of a Fiat Panda.

Have a nice weekend.

[declang]

Thanks John !

I spent ages doing the valve adjust and trying to measure valve lift, so lots of revolutions.

I happened to check #5 leakage again, and now it is down to around 20% (from 50%)
Valve clearance was a little tight, but not too bad. I adjusted it anyway.
I'm hoping the italian tune-up will help !


I didn't find any 12mm atf nuts.

When I was buying the stainless wave washers, I bought some other washers & nuts, etc, all stainless, so I thought I'd stick 'em on instead of the old zinc plated ones.

Guess I'll take them off again. I didn't torque any of them yet, so an easy job.


Fiat Panda, eh. Interesting.

[declang]

Not much prgoress since..

I took off the stainless nuts & put on the old steel nuts again.
Both TB's in place now.
I refitted the stack to 4-5-6

I got carried away & refitted the upper cam covers
Forgot I still had to measure the total valve lift when I get the new dial gauge !
I hope the gasket will survive for a second use, as I don't have another ?

Next job is to refit the rear electrical box.
I've shortened those crazy long screened cables & fitted a nylon braided sleeve.
Just have to crimp & solder the spade & ring tags on the ends now.

Cleaned points (not bad at all actually), refitted & gapped.
Vacuum advance works nice & freely.