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Discussion Starter #1
I apologise for this question as it is likely to sound vague.

I have had a car sitting for 9 years, I inherited it.

It is a 1973 1300 GT Junior.

Obviously the fuel would have been garbage. I had the carburettors reconditioned (i believe that they are Solex, not Webber) however I can confirm this.

My issue is that the mechanic is having difficulty tuning the carb and that it is apparently idlying rough / inconsistently.

The mechanic does not seem to have an extensive history with Alfas (I know I know) but is very good at his job.

Are there any hints or tips you can give me? I think the fuel in the car may be 91 octane unleaded, I will be running it on 98 octane fuel (does that make a difference)

He doesnt have the airflow measure device yet, is this important?

Any help would be greatly appreciated.
 

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Discussion Starter #2
From reading another thread a reconditioning of the carbies may not be enough if just a rebuild kit was used?

If so, what also should be performed?

cheers
 

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`61 Giulietta Spider, `65 Giulia Ti 1750, `69 GT junior 1600, `73 Spider 2000, `74 GTV 2000, `98 156
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What`s your version of reconditioned? If the car has been sitting for quite some time a full strip down and hot bath is normally required to clean out those tiny passages which get blocked when the old fuel breaks down. Essentially they are simple devices, easy enough to set up if the mechanic has some experience of multi carbed engines.
Despite what many (who don`t really know) think the Solex`s are very good and like the other two alternatives keep their tune well as well as giving equal performance. Their only negative is that if the engine is ever modified jet and component selection is nothing like the Weber and Dellorto carbs and the shafts run directly in the alloy casting making it more expensive to repair compared to the bush or bearig the other two use.
The idle jets being the finest jet/ associated passaging in the carb can jet blocked or partially blocked easily so may require removal and cleaning more than once to get right once fuel begins to flow through again it tends to pick up casting swarf etc for a while.
One thing I have learnt though through running a workshop is never assume it is the carbs fault-check the seal to the ports-are those rubber carb mounts not split and the support bar reinstalled? Is the ignition system healthy and ignition timing correct? Do you still have even compression? It pays to check these things first before blaming the carbs.
 

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As Richard says start with the simple stuff.
My car had a similare lay off and was then running rough. I discovered it was the rubber carburetor mounts that had perished.
If the car will run gently push the carbs up and down so that any splits in the mounts will open/close. If the running of the engine changes as push/pull it is the mounts.
Chris
 

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Discussion Starter #5
As Richard says start with the simple stuff.
My car had a similare lay off and was then running rough. I discovered it was the rubber carburetor mounts that had perished.
If the car will run gently push the carbs up and down so that any splits in the mounts will open/close. If the running of the engine changes as push/pull it is the mounts.
Chris
Gents,

thanks for your input. I can confirm that I did purchase 4 new carbie mounts, with the appropriate gaskets and inlet manifold gasket.

I know practically nothing about cars so this has been a learning process for me.

So far my car has 4 reconditioned calipers and 4 new pads
4 carbie mounts and gaskets
reconditioned brake servos
reconditioned brake master cylinder
Radiator fan
brake line hoses and steering tie rod ends
wiper motor and switch, new wiper arms and wiper blades

clutch master cylinder was done not too long before the car went off the road
as well as other stuff that I can't recall off the top of my head.
 

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Despite what many (who don`t really know) think the Solex`s are very good and like the other two alternatives keep their tune well as well as giving equal performance.
How come then I can buy a Weber Conversion Kit ?
You don't see many Solex Conversion Kits around ;)
Ask anyone who owns a Mini Cooper.

Once the spindles in the Solexes wear an oval hole in the carby body and then start to run lean (and untuneable), for the expense of repair it's just as easy to get a good pair of Webers. And then of course there are the tuneable components - lots and lots for Weber (and DellOrto), not a lot for Solex.

As my Alfa mechanic (of many years) once quoted me - If you own a Citroen, run a Solex, however if you own an Alfa, run a Weber (or two).

I don't mean to start an argument here, but there are quite a few of us around who actually 'do know' and will tell you from years of experience that for our cars, Weber DCOEs are the best, followed very closely by DellOrto DHLAs. Solexes were fitted by Alfa as an early concession to pollution control.

On a much more serious note, I hope that you and your loved ones are safe in Christchurch after the terrible devastation.

Regards,
Chris
 

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`61 Giulietta Spider, `65 Giulia Ti 1750, `69 GT junior 1600, `73 Spider 2000, `74 GTV 2000, `98 156
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Chris, I have actually started and owned for some years a business called Italtune in ChCh specialising as the name suggests engine tuning-not just for Italian cars by the way and s have a lot of experience. The Solex carbs perform very well on a standard car, equally as well as the other two makes and subjectively feel similar to Dellorto`s which give better low throttle engine response due to superior idle circuitry.
You are right in that (as I stated above) the throttle shafts sit directly into the carb body and can wear a greater hole allowing "false air" HOWEVER I haveseen lots of Alfas with BIG mileage on them which have not worn a bigger hole in the casting and still provided excellent reliable service. Putting a bush in is not, certainly in Christchurch, an expensive exercise and the need to do this is not common. Webers and Dellortos DO however offer an advantage in allowing one (if modifying an engine )to have a greater selection of jets, venturis etc to custom fit an application.
I have run Webers, Dellortos and Solex`s on the same engine on a dyno session to see which if any offered an advantage and both the Dellortos and Solex`s offered a small advantage in initial power and torque to about 2700rpm over the Webers but above that all exactly same with exactly the same graph.
BMW by the way used Solex`s on their 2002ti so they have real credentials insofar as power/sporting nature goes -certainly in their side draught series as fitted to these and Alfas. Adjustability and a small advantage is easier refurbishment are the only real advantage Weber and Dellorto carbs have got-and of course greater availability of parts outside Europe.
 

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From my experience, Webers are popular because they are simple, robust and the real thing from Bologna are very well built. They also don't seem to corrode internally like I've seen in some Solexes. From a totally qualitative perspective, they look good - simple, functional and the DCOE series at least, are instantly recognizable.

Weber, Solex, Dell'Orto - viva la difference though nowadays, Solex and Weber are both owned by Marelli.

Stay well, our thoughts are with you guys across the ditch.

Chris
 

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Thank your lucky stars they never used pierbergs. Modern mechs dont often work on carburettors. You need and old guy like me but you would not like the bill! Happy to pm tho.
 

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I didn`t know Marelli had Solex under their wing. It was a German manufacturer once wasn`t it? Is Weber/Spica still in existence or morphed into something else-I understand a Fiat corp subsidiary anyway.
my experience generally has been the Webers are the ones that corrode internally first. We had many an Alfa running poorly with the rearmost cylinder idle circuits blocking-very common if car been sitting for a while or used hard after a long period of easy use around town.
Thanks for the best wishes Chris.
 

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Without wanting to hijack your thread, I didn't think this deserved a thread all by itself.

I have a Guilia 1300 TI which has the single two-stage Solex carbie. The second barrel is meant to be activated by a vacuum activator, but that seems to be not working in mine. The symptom is that I must use no more than about 1/3 throttle, just let the engine wind itself up, or it fouls the plugs - presumably when the second barrel is involved it combines with the fuel from the first to change the mixture as well as the volume of fuel delivered.

I'd appreciate one of the carburetor experts here telling me if they've seen this symptom, and if my diagnosis (faulty vacuum activator) is likely to be correct.
 

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I didn`t know Marelli had Solex under their wing. It was a German manufacturer once wasn`t it? Is Weber/Spica still in existence or morphed into something else-I understand a Fiat corp subsidiary anyway.
Solex was originally a French company and as well as supplying carburettors to European cars were also made under licence in Japan as Mikuni-Solex. In 1994 the carburettor part of the company was swallowed by Marelli and changed its name to Magneti Marelli France.

As for Weber, they were taken over by Fiat in 1952 after Edoardo Webers' death in 1945. Carburettor manufacture continued in Bologna until it was transferred to Madrid, Spain in 1990. Webers are still made in Spain to this day.

A couple of years ago I was visiting Bologna and had the opportunity to have a look around the old Weber factory - it is now part of Magneti Marelli Powertrain and is largely an administrative centre. I was shown around by two ex-employees who were there during the final days of carburettor manufacture. There is a small and very interesting museum full of significant carburettor models and even a few engines. It was a fascinating afternoon, capped off by a frantic drive back to my hotel in central Bologna in the back of one of the tour guides Fiat Punto.

I'm not sure who owns Spica now and Magneti Marelli is a subsidiary of Fiat.

Regards,
Chris
 

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Cliffoedh the vacuum actuator is what I would be looking at first-these carbs are similar to the Fiat 125`s that came out with Solex twin choke (the alternative was the Weber).
The accelerator pump diaphragm would be worth looking at as well BUT before I looked at the carb I would be double checking compression as the secondary choke relies on vacuum, it isn`t from memory purely mechanical and poor compression can affect it.
Chris, that info is interesting -I envy that trip of yours and the old factory visit would have been fascinating. Was hoping to be visiing Italy and France this yer so could see these things myself but I doubt we will now.
 

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Cliffordh the vacuum actuator is what I would be looking at first-these carbs are similar to the Fiat 125`s that came out with Solex twin choke (the alternative was the Weber).
I removed the top of the carburetor and the cover for the vacuum pot, and it all looks perfect, goes up and down nicely, etc. You can see the little o-ring over the vacuum hole, see picture. I don't know whether the vacuum actuator is functioning or not. Is it meant to activate under no-load situations, or only while under load? How can I test whether it's working or not? I'm fresh out of gnomes interested in riding inside the engine bay while I drive. :)

The accelerator pump diaphragm would be worth looking at as well BUT before I looked at the carb I would be double checking compression
This engine has excellent compression, so I don't think its that. What symptoms would the accelerator pump diaphragm cause? Because it's not pumping the throttle that causes fouling, rather it's simply holding the throttle open too wide.Wait; wouldn't a wide-open throttle kill the vacuum? So maybe there's a different problem. I don't really get it.
 

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Clifford,

I don't know much about downdraft Solex carburettors so I probably won't be much assistance.

I think the carby fitted to these cars was the C32 PAIA. I don't know whether you have much information so I've attached a picture that may either help you or someone else if they make suggestions on the forum.

The key to the diagram is -

1. Choke assembly
2. Choke plunger
3. Choke plunger stop
4. Choke air jet (not shown)
5. Needle valve seat
6. Needle valve gasket
7. Filter gauze
8. Accelerating pump outlet valve (not shown)
9. Accelerating pump nozzle (not shown)
10. Air correction jet
11. Mixture tube
12. Choke tube
13. Idling jet
14. Accelerating pump
15. Main jet carrier
16. Idling mixture adjusting screw
17. Main jet
18. First barrel throttle
19. Second barrel throttle
20. Accelerating pump inlet valve
21. Accelerating pump bypass jet
22. Float
23. Choke jet
24. Vacuum chamber
25. Setscrew and locknut for securing choke tube
26. Accelerating pump linkage
27. Second barrel throttle adjusting screw
28. Distributor vacuum connection
29. First throttle idle adjusting screw
30. Choke control level

B. Fuel inlet

From the previous posts your problems may now concern part 14.

My understanding of vacuum actuators is that they work when the engine is under load and just looking at them while you blip the throttle with the car parked and in neutral (ie: no real load) won't tell you much. If there is an external vacuum port you will be able to test the diaphragm in situ, otherwise a visual inspection, as you have done, is really all that you can do.

Finally, you'd reckon that if the carby has been overhauled and rekitted, then the accelerator pump diaphragm would have been replaced.

Hope you get your problems sorted soon.

Chris

PS: It's not too late to replace it with a Weber :p
 

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I've attached a picture
...
From the previous posts your problems may now concern part 14.
...
My understanding of vacuum actuators is that they work when the engine is under load and just looking at them while you blip the throttle with the car parked and in neutral (ie: no real load) won't tell you much. If there is an external vacuum port you will be able to test the diaphragm in situ,
...
PS: It's not too late to replace it with a Weber :p
Thanks for the diagram! The photo I shared is looking down on the internals of part #24, the vacuum actuator. The vacuum port is through the little o-ring you can see, so no external port unfortunately. I also had the same understanding about it only working under load, hence my comment about gnomes :).

Wtt the accelerator pump, I thought those gave an extra blip of fuel only while the accelerator pedal is moving down. This is not a problem, that's working fine. It seems to be holding the throttle too far open that's causing the problem. Opening it a little, and progressively as the revs increase, causes no problems, but opening it wide early on causes fouling.

Regarding conversion to a Weber, this car is very original, even with all floor and boot mats intact, and mostly in original paint, so I'm reluctant to do anything to change that.
 

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You're right about the accelerator pump and you can usually see it work if you look down the barrels and open the throttles quickly. I only mentioned it because Richard J. was suggesting it as a potential problem.

Sometimes I've found that using Colortune type spark plugs helps with these types of issues (Gunsons colortune 14mm spark plug). You can see the colour of the flame and diagnose problems due to fuel mixture quite easily.

Is the distributor advance mechanism working OK ? It certainly seems to with gentle acceleration but if the engine stumbles and runs roughly it may be sticking.

My general experience is that the poor old carburettor gets blamed for a lot of engine ills. Carbies are basically passive devices that meter fuel in response to a pressure gradient, though occassionally they have active components (eg: accelerator pumps). Engines run well when all components are in good order and set up correctly - from the type and quality of the fuel, to the fuel pump, timing, points gap, coil, plug leads, plugs etc. etc. You get the picture and from the sounds of it have checked all of this. Have you tried asking the local mechanics as it's always difficult diagnosing problems from a distance.

As to the Weber - I was only kidding. If you have a nice original car, keep it that way. Post a photo or two of it sometime.

Please keep us informed.

Regards,
Chris
 

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Timing is a definite possibility. I believe the normal advance mechanism works properly, but this dizzie has no vacuum advance. A PO changed to optical points firing CDI, so might have removed vacuum advance, or possibly the 1971 Giulia 1300 TI had no vacuum advance in the first place. Does anyone know whether it should?
 

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Timing is a definite possibility. I believe the normal advance mechanism works properly, but this dizzie has no vacuum advance. A PO changed to optical points firing CDI, so might have removed vacuum advance, or possibly the 1971 Giulia 1300 TI had no vacuum advance in the first place. Does anyone know whether it should?
I don't know about the vacuum advance - someone else on the forum will have to answer that one. My Alfa is a 1970 1750GTV and it had, as standard, a Bosch distributor with a mechanical advance system.

As a first step, I'd bypass the CDI and go back to a standard set of points or install a Hall effect system (Electronic Ignition Conversion Kits for Alfa-Romeo). They are connected in the same way as points and fire the coil directly. Before I fitted my car with a 123ignition distributor, I substituted the points in this way and it not only worked very well but still looked original.

CDIs were the first of the 'electronic' ignitions and if you could get used to the high pitched squeal that many emitted, they worked well until either the stepup transformer or the main capacitor or both started to age. I think my old motor mower is fitted with one.

Chris
 
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