Alfa Pages

[mg907]

As I wrote in my introduction, since September 2011 I'm the proud owner of a nice 3th serie 33 (see pics there).



Before the purchase I didn't perform a long and deep road test, because of the extremely cheap price...so I began to notice
something wrong after one or two weeks

So I'd like to ask your advice.

Here are the symptoms list:

- Starts immediately both with gasoline and lpg
- Performances are really good with gasoline, going down slightly with lpg
- Idles quite well both with gasoline and lpg (with lpg idle is a little higher)
- Some vibration when idling
- Runs rough expecially between 2K and 3K rpm (but not really misfires)
- At higher revs vibrations seem to disappear, maybe because their frequence gets higher
- Car strongly shakes under load at those revs, expecially during uphills
- Under load the engine sound is not uniform but similar as going on 3 cyls, but not identical
- The gear lever shakes as well
- This behaviour is almost the same both with gasoline and lpg (a little worse with lpg than with gasoline)
- Cannot really say if it is running on 3 cyls, but something similar
- No explosions from the exaust, even on long downhills, just some popping when idles.
- Old Lodge 25HL spark plugs replaced with brand new NGK BPR7ES. No apparent improvement
- No differences in aspect and color between the old plugs when I replaced them
- Spark plug wires replaced because a little discharge was noticeable in the dark. No difference
- The distributor seems OK (not replaced)
- No strange noises seem to come from tappets or valves
- No water or oil consumption
- Both timing belts position is perfect (both marks on the pulleys correspond to the T mark on the flywheel)
- Ignition advance not checked (I have no strobo light)
- Pneumatic advance pipe correctly connected to the distributor
- Maybe a compression test should be worth (I'm planning to buy the tester)

Any suggestion is appreciated!

Sorry for having bored you ...and enjoy your boxers!


Mario

[BigAl]

Hi Mario
I would first check the balance of the throttle bodies and then try a different AFM, or if you can open it up and check and clean the tracks.
Check for any air leaks
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

[Bobkelso]

Hi, first try as suggested by BigAl.
(balancing carbs and checking for air leak,
like one rubber pipe disconnected from a
carb or connected in the wrong place,
leaving an open hole to get air in).

One other possibility is a valve non working perfectly,
the rest of the motor being perfect (no oil consumption).
I also experienced that on a carb boxer with very few km,
it really looks new, all metal surface without trace of time
or oxidation, and I mounted it without open it to control the heads,
but unfortunately my motor should have had some problems
with previous owner (probably an error with the belt positioning/
tensioner regulation, that bent little a valve or
it was kept stopped too long and a valve seat rusted,
so the valve seat was burned when motor was reused,
or LPG mix was too low on a cylinder for bad/bent
pipes and very high temperature burned a valve).
Same symptoms of your, running rough expecially at LPG
and low rpm, at higher rpm compression is quite regular,
with few vibration (and less transmission to the body car
as frequency is higher and "impedance" doesn't match).

In my case it was an intake valve, so keeping out
the filter box I could easily hear a different noise
(really bigger noise on revving for detonation non well
contained and "air leak"noise at idle for not detonation)
from one cylinder respect the others,
you can do this test easily.
But if it is a problem with an exhaust valve
I don't now a simple test without removing
the exhaust manifold (you can try hearing
the sound at the escape, if you notice irregular
detonation? or use a stethoscope on the manifolds?)
Compression test can give a more reliable answer.

What I tried:

One try it can be do "italian job" (valve cleaning):
a travel in 4°gear at 5000/5500 rpm at gasoline,
maybe with addictive for valve cleaning in the tank,
but I thing it works only for very small damages
like carbon deposits on valves or
very light burned/rusted seat valve
(not working with sticky or bent valve or
very bad burned valve, or blocked hydraulic lifter).

If it a blocked hydraulic lifter one try is put
cleaner/detergent products in motor oil before
the next oil change.

Actually:
my motor is better but not perfect, still some vibrations,
and at low rpm has little less force than normal
(tested with acceleration from low rpm in 5°gear, in that
test my old carb motor and my 33 I.e. (Imola) were better).
I'll have to open the heads and do classic maintenance,
also because I don't like this sound the motor do,
there are some more frequencies than usual,
it seam more "rumor", like sport car or motorcycle,
but it is less the relaxing "music" boxer usually does.
_________________
Alfa 33

[gritsop]

before anything else please post photos from your engine bay. There are many pairs of eyes looking at this forum so there is a high chance to notice something that you miss

regards
_________________
Thanassis Gritsopoulos
1991 Alfa 33 1.4 IE
2001 Alfa 147 1.6 Distinctive

http://www.alfa-restoration.co.uk
Parts Shop: www.alfa-restoration.co.uk/shop

[lee16v]

From your description I'd be inclined to think you have a burnt valve. Do a compression test.

[mg907]

Hi guys,
first of all I've to thank everybody for the prompt reply and in particular Bobkelso for the long and detailed one.

I think it should make sense making a diagnosis before start replacing components without really understanding what it's really wrong.

As a first step I carried on BigAl's suggestions, but carbs seem well balanced. I tried to add more throttle to on bank and less to the other (and then the opposite) without noticeable difference.
So I put the balancing screws back as before.

Second step: air leaks. I sprayed a few of WD40 near the joint between carbs and intake manifolds, expecting a rise in RPM
when spraying close to an hypothetical air leak. No result so I suppose there are no air leaks

Third step: replacing the upper cover of the ignition distributor: I'm waiting to go further in the checklist before doing it because it looks in good shape and I don't want to replace spares without any real need.

fourth step: looking at the carbs little pipes. I think Bobkelso was speaking about the little ones connected to the oil vapor
recycling system. I tried to disconnect them one by one without dramatic change in the engine behavior.

Fifth step: looking for a bent or burn valve (as suggested by Bobkelso and lee16v) . I still have to perform that check. I found on ebay lots of nice compression testers, not really expensive, but all coming from the UK, and I do not like to wait for a long shipping time.

So I'm planning to build something by myself in order to blow some pressure air into the cyls from the spark plug hole with the help of my trusted air compressor.
When a cylinder is at its TDC with both valves closed air should flow only into the crankcase through the cyl segments. No air flow
should reach the intake and exhaust manifolds, if valves provide a good compression. Obviously it is not easy to find the TDC for other cyls but the n. 1 because there is no way to inspect the position of the cams in the hydraulic tappet-boxers. I'll have to see at the position of the ignition rotor in addition to the flywheel marks to overcome this difficulty.

I'll keep you informed about the outcomes.

Before stop writing this long post, two more general statements reflecting my opinion:

First:

LPG gives a fantastic help in engine diagnosis, mainly for two reasons:

1) It's a great amplifier of every tuning or mechanical issues
2) Makes you able to exclude everything related to the carbs if the engine doesn't work fine both with LPG and gasoline as well.

Second:

engine sound is extremely important in boxer engine Alfas, as it is one of their most appreciated characteristics.
A car stereo is needless in such a car, even if you like music very much listening to the engine music is always the best choice.

So if the sound is not "relaxing" as usual but it is rough and uneven my 33 is 50% less attractive than it could be!

Thank you again and have fun with your Alfas

Mario

(p.s. as advised by gritsop pics of my engine bay are going to come soon)

[Bobkelso]

Hi Mario,
About the check of the little pipes:

- yes, I mean the little ones connected to the oil vapor recycling system

- but also the pipe for the vacuum ignition advance
(one time I had this pipe connected in the wrong place,
on one of the pins on the carbs that
keep closed the holes for the vacuometer '',
so one carb was getting air from the remaining hole..)

- verify also little pipes that carry LPG to the air intakes
(this rubber pipes can be 2 or 4), if one is too much
bent, so obstructed (or there is one obstruction/bent
in the cooper joints, at the ends fitted inside the 4 aluminium
'grid/nozzles' for the gas that are bolted on the carbs)
may be you have one cylinder running very low LPG/air mixture,
so a dangerous mix of misfires or very hight temperatures
depending on rpm, I think a problem like this could
initially burn a valve and after keep it constantly burned.

Normally if the LPG/air mixture is keeped correct
(not too much poor) the boxer valves shouldn't burn,
as the temperatures at the valves remain only slightly
higher than normal (with LPG, instead with methano
temperatures and troubles are more serious) and in a range
still apceptable for the strong materials of these motors.
I think so because I had seen many 33 with LPG that
just keep going on for years without heads problems.

Good work!
_________________
Alfa 33

[mg907]

Hello all,
I followed BobKelso's advice and I checked all the small pipes coming from - going to the carbs. They all seems well connected to the
right places as the pneumatic advance pipe showed in the following pic



In the meantime I'm still working to exclude electrical/ignition causes. Spark wires still have some very little discharge visible in
the absolute dark. I'm planning to replace them all. I wonder if even the distributor-coil main cable must be of resistive type as the on in my car. Anyway I
checked the distributor cover and rotor once again and the seems in good conditions. Even the distributor shaft has no free play...




Then I made another test, trying to disconnect the ignition to one cylinder at time, aiming to individuate which cylinder makes less
difference to the engine behavior when deactivated. I used the DIY tool in the pic, connecting the black thick cable to the distributor
and the thin brown one to the body ground, in order to prevent damages to the coil.



The outcome was surprisingly that none of the 4 cyl spark plug disconnection makes a big difference from the others.
Engine runs on 3 cyls every time at the same way. So my hope to find out the bad cyl in such a way was disappointed.

Next step: run my own compression test with this other DIY tool I built for the purpose.



I'll plug it in every spark plug hole at TDC blowing compressed air to find out leaks from the valves.

It's all for now. If you want to listen to my engine sound, please download the following mp3.

My advice is to listen especially to the last part of it because at the beginning there are some hesitations due to the cold engine.

http://www.ginograziano.altervista.org/111_1484.mp3


Many thanks to everyone once again!!!

Bye

Mario

[john 33_16v]

Mario, you are one resourceful fella .

Good luck, hope you can sort out your problem soon.

John
_________________
If it aint broke, fiddle with it until it is!
- - - - - - - - - - - - - -
93 33 16v Mirtle Met
08 Fiat Grande Punto Exotica Red
90 Yamaha FZR600 Genesis- Silky white/red/blue

[Bobkelso]

Hi Mario,
very clear sound recording, it seams a professional one ''

I don't have understood if you changed HT cables
with new ones or with another old set to do a test,
as they should not show dispersions if new, and
if you checked also the HT cable from the ignition coil.

Hope this can help you:
one time my motor did the same rumor of your when it had:
- one valve non perfect AND dispersing high tension cables,
sometime at idle it was like running on 3 or 2 cylinders,
had some shakes in acceleration, and
I cannot identify clearly a specific bad cylinder
doing the "one cable removing" test,
as the problem was also the ignition coil HT cable that
was dispersing to mass (sometimes also visible in the dark) ''
with more noticeable effect running on LPG,
as is easy to have misfire on LPG with weak sparks.

I changed HT cables, all five (also the ignition coil one)
and it was really better, it remains only the unusual
rumor from a specific valve and very little vibrations
(I'm programming to do maintenance).

About cables:

First original Alfa set of cables was something like
'Cavis' - Class B (140°C) type with hipalon insulation;
this cables after some years near the motor heat and oil vapor
are well cooked and dispersing; after some years Alfa/Fiat
used better ones - at least Class C (220°C) type with silicone
insulation (I think they are the basic standard also today).
Both these sets are no long available for the carbs 33.

So I searched a set of cables but it seams it
is not easy to find one with the right length
for the carbs version of the 33 boxer
(every version of the boxer had different
sets depending on the ignition system and year).

In my carbs boxer cables are classic resistive type
(something in the range 7000-5000 ohm x meter;
you can use also 3000-2000 ohm x meter racing cables
for stronger spark but in that case I think you are
starting to use the ignition system out of original
specifications, maybe with quick deterioration
of the spark plugs or other components).
Before replace the original cables I measured them
(from electrical connection to electrical connection):

- 733 mm cylinder 1 and 3 (I think standard is 730/720 mm)
- 645 mm cylinder 2 (I think standard is 650/640 mm)
- 635 mm cylinder 4 (I think standard is 650/640 mm)
- 596 mm coil

The best match in length and aspect (same rubber pipe
old style on the spark plug) that I founded was
the set of 5 cables 'Beru ZEF 801', economic (55 euro)
and good quality (Class C -220°C - 40000 Volt - silicone):

- 700 mm cylinder 1 and 3 (little short with LPG parts bolt on carbs but ok)
- 650 mm cylinder 2 and 4 (ok)
- 600 mm coil

Before to install new cables I enlarged and smoothed a bit the
entrance of the cable retention clips on the carbs and motor,
to avoid to punch the new cables insulation when positioning
them and verify they don't touch hot metal parts to assure them
long life. My old cables were in very bad condition also because
for a while they were mounted without all the clips and touched
hot parts (the oil filling pipe and the air intake conducts)

There was also the Bosh kit similar to the Beru one
but for the carbs version it costs twice than
a 8/9 mm racing cables set ''''
_________________
Alfa 33

[mg907]

Hi all, just a quick update on the topic....


Spark Plug wires.

I'm finally sure that it isn't a matter of wires. Even if there are still some minimal discharge they are not so bad and do not cause
any engine misfiring.

Anyway I'll follow Bobkelso advice and I'm going to start searching for the Beru ZEF 801 wiring replacement that seems to have a good
value/price ratio. In the meantime I replaced the coil-distributor cable and there are no more discharges visible in the dark now.

But I wonder if it should be possible make this engine running with normal copper - noresistive cables when resistive spark plug are mounted
(as my NGK BPR7ES are). If it is possible it should be easy and cheap build the cables by oneself, using the spark plug wire,
easy to purchase for few euros per meter.


Checking cyls compression

The usage the DIY air tool was a little disappointing: blowing pressurized air into each cylinder, it's not easy to discover any perceptible difference between cyls. Always the engine tries to move the car forward even if the hand brake is on. Pressure arise to 80-90 psi (the max provided by the air compressor) and goes down smoothly with no evidence of air leaks from valves. The real thing is that my home made air tool cannot work at 100% as a compression tester, it is not able to make you aware of little compression
mismatch between cyls , so I'm planning to buy on Ebay a true compression tester.

Listening the noise

With the engine idling without air filter, with the help of a piece of hose I was able to find out and listen to a noise coming from the air intake of the n. 1 cyl. carb, a sort of tac-tac-tac, that can be clearly heard only from there and not at all from the other carb.
The source of noise is highlighted by a red arrow in the picture.



So I suppose that there should be something wrong in that cyl, maybe a valve not closing properly.

Observing spark plug.

In the days before I drove the care mostly with LPG. I found something strange checking the spark plugs. Cyls 1 and 3 spark plugs look
almost white and cyls 2 and 4 ones are pretty brownish.





So I suppose that, running on LPG the right bank (from the driver perspective) receives a lean LPG/air mixture. Maybe the LPG pipe splitting device containing the regulation screws do not share the same
amount of LPG to both the cyl. banks. I'll carefully search for any obstruction or air leak on lpg pipes, as suggested by Bobkelso

But maybe the asymmetrical LPG splitting device can take the blame of that????



Anyway in the next day I'll avoid to use LPG and I will let the engine run only with gasoline.

Conclusions

Extremely lean LPG/air mixture to right bank may have caused some damage to a valve of cyl 1. That can be noticed even running on gasoline (vibrations).

When running on LPG the symptom is actually more evident because in addition to cyl. 1 damaged valve, right bank receive
a too lean LPG/air mixture as well.

Does it makes sense?

Thank you to everyone and especially to Bobkelso!

I'll keep you informed.

Mario

[33bits]

Hi Mario, i had a similar problem to this a few years ago and i too tried EVERYTHING to solve it, it ended up being a fault with the high tension ignition system, 1 of the plug leads had a wierd fault and was somehow earthing out at certain revs. (it was a 2.0 75 so there were 10 HT leads). After an expensive set of decent leads along with a new distributor cap all was healthy again.
Welcome on here and i hope you soon get this fixed. Alex.
_________________
155 sportpack
33 16v Sportwagon
33 Permanent 4
33 16v (for sale)
156 JTS sportwagon
contact me for any 33 parts. Alex, 07896-327708

[Bobkelso]

Hi Mario,
here you are doing an interesting post for similar problems.

Unfortunately if you have heard some strange sound from one
cylinder there are some probabilities of a mechanical problem
(valve / valve springs / hydraulic lifter).
You can try to use the car with a valve cleaner addictive added
in the gasoline tank (about 10 liter of gasoline and the addictive),
is a quite inexpensive try. I tried also a hydraulic lifter cleaner
addictive in the motor oil 20 min before oil change. Little improvement.

I also tried 'water cleaning':
spraying water on the intake conduct to break eventual carbon
deposits on the valve stem or valve disk but it didn't do improvement,
may be the problem was different or it was to much difficult to dose
right water and rpm (if you put too much water or not well sprayed
you dry the oil from the metal parts and heard bad dangerous
rumors from the cylinder, if you put too few water the process
of 'water cleaning' is too much long). Some mechanics know this
method but consider more safe and practical open the head and
do a classic inspection and cleaning.

About ignition system:

- distributor air-gap distance, cables resistance,
spark plug type, coil power, are calibrated together
to get reliable sparks at every rpm,
if you use normal resistive cables but with different
spark plug type maybe you have weaker sparks;
I read that cable and spark plug can be of different resistance value
and also of capacitive type, if I understood what it means in practice,
they change very much impedance with frequency, so mixing
different components (for example resistive cables and too much resistive
spark plug) can result in bad spark at some specific rpm..
I hope somebody here can say something more specific about,
I'm just starting to learn about electric specifications of the ignition parts.

Moreover, there are also many legends about the necessity to use
the original type of spark plug on the 8v boxer, they say that
electrodes different from the original 4 ways system can do misfire or,
if too much long, do spark directly with the piston doing electric corrosion.

About GPL system running lean or asymmetrical:

if cylinder 1 have make less depression in the aspiration conduct,
for me it would have sense that also cylinder 3 get less gpl,
because in these system the gpl is obtained by depression
and in your system the cylinder 3 and 1 shares the same gpl pipe.

If you can, verify also the valve/splitter you put the photo,
if some asymmetry/obstruction is present in the inner parts
or play in the valve screw. In gpl system a typical error/problem is
when the cooper pipe joints are been fitted (screwed in) too much
in the other parts and so where little crushed in the inner part,
not visible but reducing the open section / gpl flux;
in my system I had also to test the rubber pipes as I have four of these
instead of two, so they are quite small and when bent too much
one can have a reduced open section/ gpl flux respect the others.

Until you are sure about what exactly the problem is, may be
you can try to open a little (10-20°) the principal gpl valve
(the one you put the photo) to see if motor works better and
avoid damages due to lean running on some cylinders.

In my motor, I have marked with pencil 2 regulations on that valve:

1 - minimum CO2 tested with the exausts probe at 3000 rpm,
only to use for periodic controls
(ideally it should be the perfect regulation, but in practice these old
gpl systems without electronic controls cannot get the same right
regulation at all the rpm, so in practice it is a little lean running
and also some power holes in many rpm ranges)

2 - 10-20 ° more open, tested on road, for normal use
(little rich running, more safe and more power at always all rpm,
consider that gpl mixing rules are more like diesel than gasoline,
it keep on working well also in quite rich mix, of course there are
few more CO2 than best possible but still no powders at the exausts,
so still a better solution than conventional fuel).

Good work, surely you'll get to solve it ''
_________________
Alfa 33

[mg907]

First I reply to Alex...

Thank you Alex, around 1998 I owned a 75 2.0 Twin Spark as well and I had the same experience of you. My 75's HT cables where really worn and I decided to replace them with some very cheap ones. The engine didn't want to run smoothly until I replaced them again with some good quality and expensive ones. Unfortunately that car was stolen a couple of weeks after
But my Alfa 33 doesn't seem as demanding about HT cables as my old dear 75. Anyway I'm still looking for new cables, but in my village they
are not available, so I'm planning to buy them the first time I'll go to Rome.

Then to BobKelso...

About valves and hydraulic lifter I'll follow your suggestion, I'm looking for an effective valve additive to add the gasoline but at the moment I was able only to find many different injectors cleaners of several brands...do they work as well?
I'm not really an expert about those products because I was always very skeptical about them, but maybe it's now time to try them.
The water method looks really interesting but I'm to much concerned about my engine health to try it

In the meantime I made the mixture of the n. 1 cylinder a little richer and vibrations are a little less strong when idling.

About ignition system:

Now the situation is the following:

- Resistive spark plugs BPR7ES
- Resistive carbon plug wires (around 7-8 K Ohms each one with little differences due to the length, maybe impedance can vary with RPM but I cannot measure it).
- New copper wire between distributor and coil.

No discharge visible in the dark, anyway I'm going to replace everything but plugs ASAP.

About plugs I read and heard tons of discussions. Everything could be said has already been said, I can only add that Lodge 25HL plugs are expensive, hard to find and their quality is actually poor, so I turned to NGK.
A couple of months ago I was able to find Lodges at a local spare dealer for 7 euro each one, but there was some rust on them, especially on the washer, so I preferred not to buy them.

About LPG system running lean or asymmetrical:

I don't really agree with you about depression. As far as I can understand depression in the intake manifold is not affected
by bad valves, because when the piston breathes the mixture from the manifold valves are always open. Am I wrong?

I strongly agree with you about all the rest. I'm going to carefully check everything you suggested me, especially about the two different
LPG regulations and the pipe joints.In addition I'm planning to replace the all-in-one valve-splitter with a simple splitter and two separate regulation valves in the 2 pipes going from the splitter to the carbs. That for two main reasons:

- To make the LPG equipment totally symmetrical
- To be able to balance the mixture going to the cyl banks

The only problem is how to find the LPG regulation valves. LPG equipment installers usually don't like to sell single parts and normal spare parts dealers rarely have them. Even get them from the breakers is hard, because old fashion LPG equipped cars are nowadays not so easy to find even there.

Anyway, until I modify the LPG equipment I'll run with gasoline only.

Many thanks at the moment and I'll keep you informed.

Mario

[Bobkelso]

Hi Mario,
may be a good revision/control of the copper joins screwed-in
and of your valve-splitter, to eliminate major visible asymmetry
should already garantee a good balance DX/SX of the gas flux
beetwen few %, that should not cause any problems if running
LPG with a little rich mix if no other mecanical problem is present.
Still, your project of fine calibrate different LPG lines is interesting,
I think you will need a precision pressure guage to tune it.

About air depression affected by valve problems:
I'm not sure but my picture is that if exaust valve doesn't work well,
piston calls air also from exaust, so less negative pression in the intake;
if intake valve doesn't work well, air is pumped back in the intake,
so less negative pression in the intake; this can affect power of some
cylinders non only by less compression but also by leaning the mix
(bad combustion or misfire), because both gasoline and LPG
are dosed by the amount of negative pression (with very more
sensible effect for LPG both on dosing and on possible misfires).

Thinking at this post I recalled this article about how to diagnostic
motor problems monitoring the air pressure variations in the intakes:

http://autospeed.com/cms/A_111456/article.html

But usually mecanics use the classic methode,
they read the pressure on a manometer screwed on
the spark plug place, revving the motor only with the
electric motor starter (I correct myself: I see now
there are compression tester tool for 30 euros):

http://www.youtube.com/watch?v=v2l7C6QsH-s

I founded also this more expensive tool, similar to your
first idea (air compressor connected to the plug place)
but with two manometers (I think one is connected
to the pressure control and the other give idea
of the flux entering in the motor):

http://www.youtube.com/watch?v=QNf0IOIvIcY&feature=related

About cleaners I have very little experience:
I just know the ones for the motor oil (to use just before the oil change)
are petroleum based with the plus of some dispersing agents added,
they give (few?) probabilties to solve a hydraulic lifter problem;
the ones for gasoline (valve/ignectors cleaners) give (few?) probabilties
to solve deposits problem on the stem or disk of the valve
but probably for thick deposits they need to be used more times,
so it is difficult to verify if they are doing some positive effects..

For me cleaners worked half..motor is still not perfect.
I have not yet open it because in my case it is not so bad,
planning to do togheter with other maintenance works
to save some time and money (oil and belts change is arriving)..
_________________
Alfa 33

[mg907]

Hi Bobkelso, hi all!

first of all thank you for your reply and your precious advices!

I've to tell you that some days ago I brought my car to the service station in order to get replaced a worn
cv joint boot and (mainly) to maintain good relationships with the owner (I've already done this work by myself several times
although never in a Alfa 33).

He is a very nice person and his little service garage is in a lovely cottage in the country
(the location is not very convenient for people that have to leave their car there!)

Sometimes he likes better gardening than repairing cars, anyway he is always well available for good advices!

Here is what he said:

1) Alfa Romeo boxer engines love 'dancing' so I haven't to worry too much.

2) Maybe there is a bad valve but there are cars with worst ones running without problems.

3) The separate LPG regulation is a good idea but he would also add a diaphragm in the air intake of the air filter to shrink
it and to take less air in (and consequently more LPG). This should slightly affect the performances when the engine is
running with gasoline.

4) do not waste your money with the so-called screwdriver-magicians or carburetors super-experts Keep away from them!

My next actions will be...

1) I'm going to buy a compression tester from a well known Italian e-commerce site. It is quite cheap, less than 25 euros, let's hope the quality
will be good enough

2) Perform the compression test

3) Build the separate LPG regulation. I've already bought everything is needed for few euros from a Polish ebay seller
dealing with LPG spare parts. They offer normal shipping only and I do not trust so much on the Italian postal service
and I think the Polish one should be more or less the same.
Honestly I'm not sure to receive the shipping

4) After the above step I'll try the air intake diaphragm, as suggested by the mechanic

5) Finally I'll check the spark plugs again.

I read carefully your air depression arguments, and I've to say you were able to convince me!

The article on the autospeed.com website is really interesting and well written! I wonder if it is possible to
take advantage in our car by the oil vapor recycling little pipes, linked to the intake manifolds, connecting the gauges to them

About the tool shown in http://www.youtube.com/watch?v=QNf0IOIvIcY&feature=related I really cannot imagine how it could work.

I'll show you with some pics every new development!

Thank you again.

Mario

[Bobkelso]

Hi Mario,
I want say to pay attention if your car is actually shaking too
much and you use it to do many kms:
where I work they measure also vibrations, with accelerometers,
and say that vibrations in cars if are strong (due to the motor or
due to an imperfect wheel) are dangerous, not only
for the car integrity (you could have to change some spares
before usual time) but also for the driver integrity,
there are some legal limit values used as 'attention limit',
(and some cars don't respect them also when new, so they
are 'fatiguing' when you drive them on long distances,
and can have adverse effects on driver after years of use).
Ok. now I stop scaring people

About the boxer technical solution.

What I read on internet is that boxer was chosen by Alfa
because they wanted achieve superior comfort
without using counter-rotating shafts in the motor, because
they drain about 3-4 cv of power in a motor of middle-size.
Boxer doesn't have one natural 'order' of vibrations
that linear four cylinder motors have, so boxer give less
vibrations and don't give the typical strong rumor at the
resonance body car - motor frequency (the 3000-4000 rpm 'vroom')
that all normal 4 cylinder motors give.
So in Alfa Sud and Alfa 33 the central motor mounting rubber bush
(but also the front one) was projected quite solid, like sport car,
because there were few vibrations to filter.
Actually cars usually don't have a boxer motor but have really
better 'motor suspensions' to avoid body car vibrations
(is a more economic but working way to solve the problem).
Now if the boxer motor in a 33 is ok the ride is superb,
you 'fell' the motor when accelerating and still have confort,
but if boxer is running on 3, maybe the vibrations are not strong
like in a normal motor running on 3, but they are not well filtered
to the body car, as the mounting bushes was not supposed to do it,
and car vibrations can range from subtle ones to quite strong ones.
So, what your friend said about boxer that can like dancing a little,
in my opinion is correct if you refer to idle, because there is often
some minor things not well balanced in a used car, or little
difference between valves/cylinders compression, and so
idle can be perfect or a little dancing one,
but is vibrations are present also when driving is not normal,
usually 33 should be quite comfortable when driving,
so probably there is some problem to solve in the car.
As I said before actually I have same problem on my 33,
probably less evident, I have 'to search' for vibrations
while driving to notice them, but I noticed, together with
the different sound of the motor, a difference in comfort
(uhm, may be I'm a little exagerated, I notice something
different also with road bump changing tires type )
_________________
Alfa 33

[mg907]

Hi,
do not worry about frightening me, my 33's vibration are actually not so strong to be harmful for the human body,
they are only noticeable in neutral around 2500 RPM and during uphills. But, as I already said, they are not strong enough to shake the driver,
but only a little the gear lever...

Your discussion about engine suspension in boxer equipped Alfas is really interesting, I'd like to go deeper about 1st and 2nd order engine vibration
in 2, 3, 4, 5 and six cylinder engines but I suppose that here is not the right place. I only mention that I drove for more than 100K km a 350
Morini bike with a 72 degrees 2V engine linked to the frame without any piece of rubber...and I'm still alive!

A quick update about my car situation.
I received at home the compression tester




and I performed the test last week. Even if cheap the tool seems to work fine.

Before starting the test don't forget to disable the ignition!






Here are the test results:




cylinder 1



cylinder 2



cylinder 3



Cylinder 4

Values are really low but after that I was told that I should have kept the throttle wide open during the test (is it true?) and I didn't do so.

Maybe that's the reason for the low values.

I repeated the measure for cylinder 1 after pooring a little of oil from the plug hole.




A little higher...the new value measured follows:



cylinder 1 second measure

Overall results seem not really brilliant!

Anyway I will repeat the whole test with the throttle open. I doesn't want to take any decision before I'll do it again.

In order to perform the compression test I had obviously to remove the spark plugs, and I still found them having a color tending toward white,
even if I have been driving the car with gasoline since 10 days before.
I'm suspecting that NGK BPR7ES plugs don't fit very well, maybe they are a little too hot for 33 engine.

In the meantime I moved back again to good old Lodge 25HL, but I have to say that the engine runs better and smoothly with NGK

Mario

[BigAl]

What should you get on an 8v? I got 200-210 and 160-165 psi on my 16v when i did mine.
I did mine dry with all plugs removed and WOT.
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

[Brit01]

on my 8v I get 180-190 dry and 200 wet. (1988 S2)

NGK 7 I wouldn't say are hot. Remember NGK have a reverse scale.
A #6 would be hotter.
#8 would be quite cold and maybe wouldn't burn very well unless you are racing and pushing the car very hard.

I use B7ES.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Bobkelso]

Hi, nice test and photos.
Who is the internet vendor of your tester, Mario?
(I'm interested in buy one)

Car have still good power?
I think you can notice compression when driving in high gear and low/medium rev,
because at high rev compression leaks are less effective.
Some values to compare (done on safe conditions, on high-way street):

- 1.3 i.e. (Imola) in 5th gear, 13"wheels and 110.000Km was accelerating from 100 to 150 kmh
of tachimeter (real speed you know are 10% less with 13"wheel) in 17,5-18 sec.

- 1.3 v.l. (carbs) when ok unfortunately I didn't do the acceleration test,
I only see that top speed was about 3-4kmh better than Imola before mounting
the LPG system and 3kmh less than Imola after (LPG added 50 total kg more on the car
and some restriction on air aspiration before the filter)

- 1.3 v.l. (carbs) with LPG I tested it after having changed motor
(LPG worked really fine for years, the problem was I broke the driveshaft )
new motor with some little trouble at one aspiration valve and the LPG system on the car
does the 5th gear 100-150 acceleration test it in 20,5-21 sec
(running on gasoline and 13"wheel; actually on 14"bigger wheel it does it on 2-2,5 more sec,
but also tachimeter speed reading is different, now "only" 7% error)

Perhaps differences in relative compression values between cylinders
are more reliable indications than absolute values.
(may be you get lower values when testing motor with low capacity, like 1350cc,
because of the internal air volume of the instrument and of the connection rubber pipe,
or also get lower values when revving too low)

I have some questions to more expert people of the forum
about how one can compare the absolute values:

- the standard way to do the test is removing contemporaneously
all the 4 spark plugs? (I thing so you get higher revs, idem if starter motor and battery
are in good shape, and idem keeping the throttle wide open,
also to avoid effect due to asymmetrical minimum regulation of carb's butterflies..
and what about also unplugging clutch to rev higher??)

- how many oil must be used to be safe with the risk of having
not at all compression air volume and so damage motor when revving?
(I'm still trying scaring people and myself with remote risks'' '' )
and the second test done with oil to seal piston rings leaks does it work well also in boxer,
with horizontal cylinders? oil found its way all around pistons?

Ps.: BigAl, what "WOT" it is for?
_________________
Alfa 33

[Brit01]

Standard procedure would be:

Make sure plugs are easily removable first. Loosen them and then tighten them, putting some copperslip on them. This is because removing spark plugs while the engine is hot is not always recommendable as you can damage the threads.

Run engine up to working temperature.

Remove all plugs.

Disconnect dizzy coil.

Connect the gauge to 1 cylinder and spin engine with starter motor until max pressure on gauge is obtained with throttle wide open. May take 5- 10 seconds.

Repeat on other cylinders.

Wet test: (amount of oil I'm not sure - but make sure you add the same quantity to each cylinder).
Repeat as above.

p.s difference in values between cylinders should not vary more than 10-15%.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[mg907]

Hi all and thank you for the replies!

I suppose WOT stands for Wide Open Throttle, am I right?

That is the way I made the CT (Compression Test ... please don't trigger my acronyms passion on ) :

1) All spark plug removed
2) Throttle pedal untouched
3) Ignition coil disconnected
4) Clutch pedal released (engaged)
5) More or less 5 cc of oil for the wet test (only on cyl 1)


Maybe point 2 is wrong, as stated by Bobkelso, and that is the reason of the low compression values.

(4 Bobkelso, if you want to know where I bought the tester please
send me an email at mdotgrazianatliberodotit...because I don't know if I
can publish the link here)



Car still has a good power and an a really impressive acceleration even if I didn't measured it. About the wet test I think i doesn't matter the cylinder is horizontal, if you wait some minutes after pouring the oil into
the spark plug hole.

4 Brit01, thank you for your spark plugs advice, maybe BP(R)7ES are OK for boxer as degree perhaps is a matter of shape.
Is the color of your NGK #7 plugs a lovely brownish when you check them?

I know NGK scale is reversed compared to Bosch one. For example my Ducati bike requires NGK #9 plugs .

I'll do the WOT compression test again following Brit01 procedure and I'll show you the results.

Mario

[Brit01]

Mario,

Yes 2 important points.

Engine has to be hot and throttle wide open.

My plugs are a bit on the rich side at the moment (well last time it was on the road- being rebuilt at the moment). Should have it going by end of this weekend and will need some tuning.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[BigAl]

I did mine cold, try getting the 16v plugs out with a hot engine
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203