Weber 32 DAT (Coupé 1300) investigations

[Modano]

Hi !
this topic aims at discussing my findings, learnings and issues I'm running into with a 10 year-paused Weber 32 DAT (among other things).
I've collected over the years a huge amount of diagrams, books, documents, and now I'm practising them

The Weber 32 DAT is not that common (much less resources on the internet than many other Weber carbs, including parts, although the part numbers of many parts are shared with DMTR, DATR...)
I'm very lucky on this journey as I changed my Weber 32 DAT 3/250 (original one) a few months before I "paused" my car. Therefore the one in place was a brand new 32 DAT 3/251 (normally equipping 828 D3 engines), and therefore I have a spare carb to tear down, study, check etc...
BTW the original carb had nothing on spec (150 needle instead of 175, all jets were incorrect size ...)

On these models, there are not many ajustments to be made : only the idle screw on the bottom (left untouched yet) and a screw for the butterfly rest position (left untouched yet)

What was done so far
The first issue I solved were punctured floats. the spark plugs were literally wet after 10 sec (and the engine was extremely rough, hard to start, no revving up, and fuel smell in the oil). I took the donor carb for this.
I also changed the needle which had heavy marks on the conical side.
The float fulcrum was "rough" so I also took the old one.

The carb had brownish deposits (old fuel). so I gently cleaned the visible part in the float chamber.
Pipes from/to tank are free, the tank is not as rusty as I thought, and the fuel seems to come pretty clean (obviously changed the fuel filter for a MANN one)
Attached is a pic of the brownish deposits.

I only did basic accessible cleaning (blowing air into jets, cleaning with a toothbrush and fuel, cleaning inline fuel filter).
My first concerns were the float level. The specs are 7mm and 43mm for the total displacement. I had some troubles understanding the 43 mm one, but now I should be fine (see attached picture). I have to fine tune this value, and also check that both floats are at 7 mm. Will also change the metallic o ring of the needle.

The wet gasket
But, before talking about performance and ajustements, my first question is : is that normal that the gasket is always wet from fuel (I mean always, if it dried out after a while, it becomes instantly wet). When removing the top part you can see how wet it is in the picture ? I thought it was due to improper float level, but now that I'm approaching the right values this gasket is still wet.


I'll post some information and scans in the technical resources topic as well. I'll also post some videos.

[squiglyzigly]

My experience is that the gasket is always wet.
I expect it can never be dry because the fuel will always move about when the car is driven or from engine vibrations when idling.
Then there is the volatile nature of petrol. It evaporates very quickly, so the gasket will absorb the fumes.

Ian

[Modano]

Hi all

Thanks for your reply. Makes sense …
I posted a new video where you can see cold (and also warm) engine struggles when throttle is brutally operated.
Struggles range from : lack of revs, drop of revs and even stalling , backfires (!) on the second barrel, fuel droplet running away from the first barrel…
When hot it is a bit better (no backfires for instance)
What are your takes ? Too rich or too weak mixture seem to both cause these kind of behaviors.
I’ve not touched the mixture screw, power and acceleration diaphragms are original.
Float levels should be good now.

https://youtu.be/DudGaqu44tA

[hutch6610]

Bonjour Modeno.
Are You sure you have the distributor timing set correctly with a timing light? Reason i ask is that the engine sounds retarded when you open the throttle and that pop back just seems to make the case for me.
There are two types of pulleys on early cars - one that you time to the marks on the plastic timing belt cover and the later one which has a pointer bolted to the engine and requires a timing light with advance feature to time correctly.  there is a rubber plug you can remove under the wheel arch to do the adjustment.
To tune a carb the valves must be set correctly, the timing (cam and distributor) must be set correctly and the plug/points in good condition or you will be just going around in circles chasing your own tail.
Needs to be 10 degrees before TDC when engine is hot at idle with vacuum pipe removed and plugged. In your case you appear to have the old Marrelli non vacuum distributor so don't worry about the pipe.

I would personally slacken off the distributor a little and turn it clockwise about 15-20 mm and see if it improves. If it does then set the timing with a light.
Good luck.

[capriblu]

I think turning the distributor clockwise will actually retard timing further?

[Modano]

Bonjour Modeno.
Are You sure you have the distributor timing set correctly with a timing light? Reason i ask is that the engine sounds retarded when you open the throttle and that pop back just seems to make the case for me.
There are two types of pulleys on early cars - one that you time to the marks on the plastic timing belt cover and the later one which has a pointer bolted to the engine and requires a timing light with advance feature to time correctly.  there is a rubber plug you can remove under the wheel arch to do the adjustment.
To tune a carb the valves must be set correctly, the timing (cam and distributor) must be set correctly and the plug/points in good condition or you will be just going around in circles chasing your own tail.
Needs to be 10 degrees before TDC when engine is hot at idle with vacuum pipe removed and plugged. In your case you appear to have the old Marrelli non vacuum distributor so don't worry about the pipe.

I would personally slacken off the distributor a little and turn it clockwise about 15-20 mm and see if it improves. If it does then set the timing with a light.
Good luck.

Hi
I've not checked the distribution timing. AFAIK it never was checked in the past history, even when I got the cambelt replaced.
The fact is that the car was running really fine before being stored, and I had to play with the carb to solve a flooding issue, and then, with the problems I now mention, I thought that the carb needed a cleanup & some ajustments.
Is there a way the distribution got altered somehow (maybe a tooth jumb for the cambelt which need replacement btw ?).
The distribution here is a electronic one (Marelli AEI, no condensator, no breakers, just the induction sensor and the usual electronic components), but it also has a vacuum diaphragm, along the inertial rotor, so 2 dynamic systems. To be fairly honest, I cannot expect the vacuum diaphragm to be of any use, it must be long time punctured. The inertial system seems to work fine, but maybe it is "slow" and sluggish, and induces a delay.

So, is that kind of distributor ajustable as you said ?
Also, is the fact that when hot, the engine runs much better (albeit not perfectly at all), compatible with a ignition timing issue ?

[squiglyzigly]

The electronic Marelli magnetic pickup distributors are prone to wires fatiguing and causing a mis-fire. Especially units with vacuum advance.
Inside the distributor there are 2 unshielded wires that are moulded into the magnetic pickup. These are the wires that fail and cause a misfire. Eventually they break and stop the system from firing completely.
They go through external white fly lead to the amplifier/coil.

Take the distributor cap off (and maybe the rotor arm for a better view) and inspect the wires for fatigue.

Maybe this is causing your problems. If not it’s good to keep an eye on.


Good luck
Ian

[Modano]

Hi, thanks
When my engine was flooding (huge consumption, fuel in oil , impossible to throttle , wet spark plugs) I first thought it was misfiring so I cleaned up all the connectors (coil , transistor which had red gummy oil) , cleaned up the rotor cap and contact.
When I read about these Marelli I thought that the wires you’re talking about are more of a binary issue : really bad behavior or Ok but won’t cause small misfires , but maybe I’m wrong.
I have a new set of plugs, will try these ASAP
Will also share the spark plug color after yesterday’a tries. Also , after I adjusted flooding, it was running ok but a bit low in performance and a bit sluggish . The plugs were dry and white so weak mixture.
Since then I’m doing trial and errors with books and small tries 😅

[Modano]

Spark plugs (old) were sooty and black .
Putting in New ones didn’t really change anything (and they re going to be as sooty and black).
What bothers me is that suffocation when calling the second barrel when cold, and a much better experience when hot.
Wouldn’t a ignition issue cause problems all the time ?

Another question : is the brass pipe over the second barrel supposed to drop fuel at each “call” ? Here it barely brings any fuel , sometimes does sometimes doesn’t, while the Jet below seems to do okay.
I cannot find this channel in the diagrams of the DAT.

The carb had fuel residue over the time that went gluey, I cleaned as much as I could but maybe some channels are still dirty.

[Modano]

Another question : is the brass pipe over the second barrel supposed to drop fuel at each “call” ? Here it barely brings any fuel , sometimes does sometimes doesn’t, while the Jet below seems to do okay.
I cannot find this channel in the diagrams of the DAT.

I think I found out this one on the new Haynes manual : it is the full load fuel channel, so driven by the full power valve and it’s diaphragm and ball. I need to check if it is supposed to be operating only when reaching high revs or when throttling “brutally”

Edit : mistaken full load circuit and power valve

[hutch6610]

I've not checked the distribution timing. AFAIK it never was checked in the past history, even when I got the cambelt replaced.

Well my friend it should have been and the person changing the belt should have done it as it wont time up exactly where it is supposed to be otherwise.

So, is that kind of distributor ajustable as you said ?

Yes - all Beta Distributors except Digiplex is adjustable - Have you had it checked with a timing light recently to make sure it is timed to 10 Degrees before TDC? Judging from your previous quote that is a no.
It does not hurt to check it and adjust if necessary - there is a 13mm nut at the base of the distributor on a clamp which you slacken just enough for the distributor to rotate.

Also, is the fact that when hot, the engine runs much better (albeit not perfectly at all), compatible with a ignition timing issue ?

Again yes it can, when cold it revs sluggish especially when on choke and improves when hot after the choke comes off. When you snap the throttle open you get that deep sucking and crackling/ popping you see in the video. It sounds retarded, that's when the ignition fires too late, It can also cause some of that sooting of the plugs.

The distribution here is a electronic one (Marelli AEI, no condensator, no breakers, just the induction sensor and the usual electronic components), but it also has a vacuum diaphragm, along the inertial rotor, so 2 dynamic systems. To be fairly honest, I cannot expect the vacuum diaphragm to be of any use, it must be long time punctured. The inertial system seems to work fine, but maybe it is "slow" and sluggish, and induces a delay.

Then check to see if it is punctured by taking the pipe off from the carburettor and sucking on it, unhygienic i know but has never done me any harm - if no resistance then it is indeed perished and will need replacing.

Please Modano get it timed with a light before you proceed to do anything else. Don't just dismiss it as it was fine before as you don't know for sure.

Could you also tell us what jets you have in what holes. Using that photo you have posted here what combination jets are in what holes?

[Modano]

Hi, thanks for all these answers and advices.

Yes - all Beta Distributors except Digiplex is adjustable - Have you had it checked with a timing light recently to make sure it is timed to 10 Degrees before TDC? Judging from your previous quote that is a no.
It does not hurt to check it and adjust if necessary - there is a 13mm nut at the base of the distributor on a clamp which you slacken just enough for the distributor to rotate.

OK, so, my experience is still limited on ignition timing, but I'm currently documenting myself.
I have the timing chart (without the vacuum) and I guess I need to check the 10° BTDC (static) and , running high on revs, reach 27° BTDC. That would guarantee proper static and inertial advances, right ? I saw a couple of used strob lights, not that expensive. Once the setup is correct, for the 10°BTDC I just need to rotate the distributor, once the clamp is loosened. For the 27° I guess I'll need new springs/grease in case it's not properly working. (Will open a new topic)

Then check to see if it is punctured by taking the pipe off from the carburettor and sucking on it, unhygienic i know but has never done me any harm - if no resistance then it is indeed perished and will need replacing.

Definitely totally punctured, I can blow/suck without any effort. The vacuum adds an extra 12° advance, but this time depending on the depression. Cannot really measure this, I guess I'lle need a new capsule, but AFAIR it was impossible to find 10 years ago, so now....
Is this a game changer, or the proper static+inertial will already be a solid basis if correct ?

Could you also tell us what jets you have in what holes. Using that photo you have posted here what combination jets are in what holes?

I checked these. The carb was new, made in 1989 and installed in 2008. The jets are all onspec. But there may be some gluey petrol residue left in some channels. But you're right, I need proper ignition timing at least make sure we are not totally out of specifications.

[Neil-yaj396]

Coming late to this but I had years of fueling issues with my 1300. A part strip down of the carb only partially sorted this and the car only really ran well after driving to Northern Italy in two days.

However, the very rough running returned a couple of years ago and this were sorted by soaking the jets in solvent for a few days.