Alfa Pages

dtm · Alfa Arna Joined: 28 Nov 2004 Posts: 12 Location: Portugal

Hello. The idle speed on my Alfa 33 is a little low and the car runs a little irregular, but if I speed it up to about 1000rpm it purrs like a kitten. The idle speed is a bit under 750rpm and I’d like to put it a little under 1000rpm, how can I do it?
Thanks

Ben_nz · Posted: Thu Dec 16, 2004 8:14 am Post subject:

Does your 33 have carbs or fuel injection?
Does the problem occur when the engine is cold or hot?
When you say you speed it up to 1000rpm, do you mean using the accelerator?

Eddie W · Posted: Thu Dec 16, 2004 9:23 am Post subject:

There is a throttle stop screw on each carb. Screw each one in by the same increment( ie 1/4 turn) Until you have the idle speed required. Do not fiddle with the screw that adjusts the linkage between the carbs as this should have a slight clearance and you will upset the synchronisation.
Personally I too like a faster idle around 1K rpm.
Regards Eddie
_________________
A LITTLE FURTHER A LITTLE FASTER

dtm · Alfa Arna Joined: 28 Nov 2004 Posts: 12 Location: Portugal

Sorry, mine is a 1992 1.5ie and the idle speed is below 750rpm when hot, and I have to speed it up with the accelerator. At idle it wiggles a bit, sort of irregular.

gritsop · Posted: Thu Dec 16, 2004 10:11 am Post subject:

Hi,

Is your car a Marelli IAW or Bosch management system?

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

Wizz · Posted: Thu Dec 16, 2004 10:31 am Post subject:

I have a 1.5 IE '92 as well, with a Bosch system. I adjusted the idle so it sits just below 1000 rpm now, seems to work well - even on cold/moist mornings.
To adjust it, it's sorta what Eddie W said, only there's only one screw. Just follow the throttle cable.
_________________
//Wizz
Alfa 33, 1.5 IE (1992) (Series 3)... now with 1.7 IE Very Happy

bobbber · Posted: Thu Dec 16, 2004 3:05 pm Post subject:

There's a couple of pipes that go into the inlet manifold to the front/right of the car. The thick one is for boosting the idle when the car is cold.

The thin one is the 'idle bypass tube' - adjusting the nut on here adjusts the idle speed.

A small hole drilled into the inlet butterfly helps stable the idle... but that's a different subject!
_________________
Fiat Bravo 165 Sport

bobbber · Posted: Thu Dec 16, 2004 3:07 pm Post subject:

Ooh, and ...

The adjustment on the throttle cable is not for adjusting the idle, as such - should only be adjusted to stop the cable from having slack.
_________________
Fiat Bravo 165 Sport

dtm · Alfa Arna Joined: 28 Nov 2004 Posts: 12 Location: Portugal

Ok. My Alfa as a Bosh Jettronic system. So the throttle screw doesn’t adjust the idle!?
Thanks

bobbber · Posted: Fri Dec 17, 2004 10:11 am Post subject:

That's how I understand it to be.

The throttle only adjusts the throttle 'over and above' the idle speed, the idle speed being adjusted by the nut at the inlet manifold end of the pipe I've marked in red :

http://www.alfa-restoration.co.uk/img3.jpg

Hope that helps!
_________________
Fiat Bravo 165 Sport

LDA · Alfa 33 Joined: 28 Nov 2004 Posts: 276 Location: France

bobbber, do you have more of that diagram? or the key to go with it? is it one of the workshop manuals?

L.
_________________
A good workman allways blames his sh*t tools.

dtm · Alfa Arna Joined: 28 Nov 2004 Posts: 12 Location: Portugal

Thanks.
That’s a very helpful tip Bobbber