[Matthew K]

Hi all,

This may sound like a stupid question, or that I am losing my mind, but I am wondering why the choke on my 1984 twin carb GTV causes an aspirating / air rush noise INSIDE the car. Or so it seems. When I have the choke open it sounds as if there is a little tube under the dash sucking air in.

Mind you when the engine is running there is a kind of a buzz or vibration under the dash as well - maybe there are hoses touching the firewall or something.

Anyway, just thought I would ask if anyone else has experienced this phenomenon, and what could be going on.

Hey - could it be the vacuum line from the cam cover? Probably another stupid question.

Cheers,

Matthew.

 

[PSk]

If you car has Solex carburettors they have a weird choke setup (opposite to normal, instead of restricting air they add more fuel or something) which sounds horrid when used ... even scared the mechanics at my fathers workshop when I left my GTV there once.

Solution is to not to use the choke ... I never have, just 3 pumps and away you go.
Pete

 

[Matthew K]

Dell'ortos actually. I used to not use the choke at all, but I recently had the engine rebuilt and it won't hold a steady idle without the choke on for the first ten minutes or so. I've nearly finished the first thousand km on the rebuild, so I'll have the carbs tuned (they were set deliberately rich as a protective measure) in the near future and with luck I won't need to use it again. I'm also looking forward to a tuned engine which seals at the top and bottom ends!

 

[Giorgio68]

Matthew,

Does your car has a mechanical fuel pump, if so that could be going bad. I had the same problem on my Giulia Super (Twin carbs), everytime it started difficult and then got worse. I replaced the pump problem solved.
hope I am making sense, just a thought.

Giorgio

 

[Matthew K]

It does have a mechanical pump - - do you mean it's going bad because I need the choke out to hold idle, or is it because I am hearing a noise with the choke out?

 

[Giorgio68]

Matthew,

I was saying my Giulia started difficult when it was cold. I usually do not use the choke, yes it does make air noise when choke pulled. I have solex on mine.
Once the car started it was fine later, then I found out it was the fuel pump.
You can test your fuel pump to see if fuel is coming to the Carbs.
Take the fuel line off that goes to the carb and stick it in a plastic small bottle, then try to cranck it see if fuel is coming when the car is cold.
Again this may not be your problem, but its an easy test. It is always better to have a new fuel pump since you don't know when it was changed last time.

Giorgio

 

[alfahaka]

Dell'ortos actually. I used to not use the choke at all, but I recently had the engine rebuilt and it won't hold a steady idle without the choke on for the first ten minutes or so. I've nearly finished the first thousand km on the rebuild, so I'll have the carbs tuned (they were set deliberately rich as a protective measure) in the near future and with luck I won't need to use it again. I'm also looking forward to a tuned engine which seals at the top and bottom ends!

Running rich while running in is an iffy proposition - and if it is rich why would it want choke? I have never heard the noise the choke on Dellortos in a 116 alfa makes despite having owned 5 of them - not because it doesn't make any (it might) but because I've never used the choke!

I can say that you CAN hear a lot of general induction noise from inside these cars, and I wouldn't find it suprising if you can hear "sucking" noises with the choke on.

Get the thing tuned and the problem should vanish one way or the other!

 

[Matthew K]

Will do - I've been longing for the day I can have it tuned, so if there's no good reason to leave it running rich ... !

 

[Damo105]

My 105 has Dellortos, and the choke also produces an audible sucking sound, I just assumed it was normal!?

 

[Matthew K]

Actually I just had a poke under the bonnet and discovered that the vapour return line which connects to the cam cover wasn't connected where it should go through the firewall. I plugged it as a stopgap until I have time to look for the other end, and the sucking sound diminished - maybe you have the same issue.

 

[Clayton105]

The noise you are descibing sounds normal to me. Dellortos are very noisey when you have the choke on. When you use the choke, you are pulling air though a separate circuit (through the jet cover from what I remember) therefore you have a very different sound that does sound very odd.

I would be worried about this "The carbs were set deliberately rich as a protective measure" - crud... If it was a standard rebuild, set them how they came out of the factory! Too far rich or lean can cause damage for different reasons.

I always used to always rebuild carbs as part of a full rebuild. Even here in Canberra (goes to -5 regularly in winter), you could give then one poke on the accellerator, pull the choke and they would burst into life and idle straight away... when everything was set up properly.

The biggest problem with the choke on carburettored Alfas was stopping the choke cable from seizing.

 

[Matthew K]

Yes, true, in fact the transport company who brought it interstate delivered it with a stuck choke cable - it made for an interesting idle at about 3000 rpm. I'm using the choke pretty infrequently now, and it's really only a problem holding idle at the lights when it's cold.

I wouldn't say the carbs were way too rich - just tend to drop a bit of unburned fuel when I open up the throttle under load. I had them stripped and rebuilt a year ago so I'm confident they are OK. I'll get it tuned when I get the time - wish I had the knowledge and experience to do it myself.

I've had a few sceptical responses to the "set a bit rich" notion, but that's what my mechanic told me. He did the rebuild just before we moved interstate (actually *after* we moved!) so it wasn't him trying to get repeat business. Everything else seems OK thus far (750 km on) so I guess I trust his opinion, but I know there are many schools of thought on rebuilds.

 

[Tassie Tuner]

You shouldn't need to use the choke much, as others have already noted, but when you do, it's entirely normal that the carbies make more noise, with a bit of sucking noise. It's not that much louder, but is immediately noticeable. You should only need the chokes on very cold Hobart mornings - like less than 5˚C. However, as you're from Sydney, I know that you might think it's cold here all the time. My brother, who has lived in Sydney for about 35 years after growing up in Hobart, now thinks anything colder than 16˚C is cold, while I think that 16˚C is a warm winter day!

-Don

 

[Matthew K]

No worries Don - my personal thermostat was influenced by Sydney, but I grew up in Tas, so the climate feels entirely normal to me! I find I'm not using the choke much at all now that Hobart temps have climbed out of the single digits. 16 degrees is just fine with me!

Who do you reckon is good for carb tuning, etc? I've heard good stuff about Jedamzik but I know you were pretty keen on the guys in Collins Street.

 

[Tassie Tuner]

No worries Don - my personal thermostat was influenced by Sydney, but I grew up in Tas, so the climate feels entirely normal to me! I find I'm not using the choke much at all now that Hobart temps have climbed out of the single digits. 16 degrees is just fine with me!

Who do you reckon is good for carb tuning, etc? I've heard good stuff about Jedamzik but I know you were pretty keen on the guys in Collins Street.

I don't know much about Jedamzik, apart from the fact that he used to service a workmate's Mercedes several years ago, and seemed to be OK. He also took over his garage from an ex Tasmanian rally champ, Lin Gigney, whose daughter (rallying must be in the genes!) navigated for Peter Brock in Targa in a Monaro a few years ago. Lin used to be good for buying suspension parts and Cibie lights from, prior to his retirement.

Autocraft in Collins St is a good place. The Kershaw brothers who run Autocraft are Italian car specialists, and have both owned Alfas and Fiats. One of them still owns an Alfa 33 Quattro, I think. The rally blokes don't get their cars serviced there for nothing - they are real enthusiasts, and have plenty of good mechanics working for them. Just don't go in there anytime near Targa Tasmania time, as they are overflowing with rally cars then! However, I'm sure the brothers would jump at the chance to work on an Italian car. They are pretty versatile, and also do (real) 4WD servicing, and supply and fit 4WD accessories like bull bars. If you need many car accessories, like Koni or Bilstein shocks, or driving lights, they are always the first people to try in Hobart, I've found.

Another place that specialises (or used to) in Italian cars is Fogarty Automotive Services. Terry Fogarty who used to run it died several years ago, so I don't know if they still specialise in Italian cars, although I remember his widow said that she'd continue running the business like that, in a newspaper notice at the time.

Yet another place, although I don't know much about it, is a place out in Glenorchy, run by some Italians named Bocchino. They specialise in Italian cars like Fiat, Lancia and Alfa, and VW's and Ferrarri's, from memory, and also have a highly-regarded bodyworks business, I think.

-Don