Idle problem 1981 GTV 2000

[fazersix]

Well I cannot unscrew it any more! It is 2.5 turns out  the others are 4.5 and the car drives ok.
If I screw it in then I high that due to the rounding of the head I won't be able to back it out.
Beginning to think this is a drill and screw extractor to get it out and the re-tap the thread .
Has anyone done this?
Still high idle but am also thinking it is the mounts as Carlo said cos I recently changed the engine mounts and the carbs dropped without the stay on and i did notice some small cracking on the mounts (I think!)

[bonno]

The idle mixture orifice is machined to a fine tolerance and I would not attempt to drill and extract idle mixture screw. Recommend to liberally apply wd40 down the orifice and gradually remove idle mixture screw by unscrewing it in the anticlockwise direction. Ensure flat bladed screwdriver fits snuggly within the orifice.

[carlo rossi]

i have this before, and the others ended up cutting the collar off
to relieve the screw slightly under the top of screw
when you get it out get a new one it could be cross threaded

[bonno]

Here is a photo of the idle mixture screw orifice (collar) and idle mixture screw (PS photo does not include spring, washer and o-ring). 

[fazersix]

Cheers Carlo and Bonno the task looks a whole lof better now. I removed the other barrels screw and can see that the thread starts approx 10mm down from the flags which is roughly in lime with the screw head.
So cutting the collar off level with the flange should a,low me to cut a deeper slot in the screw head  well above the thread. This may take a few weeks cos I have to source the mix screw and tap (Dellorto Uk has a 7mm x .5mm tap).
Will get some gaskets and new jets and tubes as well. Will also do the carbs mounts, since they are most likely original.
Will post when I tackle the mix screw .

[fazersix]

ok popping is too lean
for those cams the settings are wrong!
you need 210 air 7772.08 correctors  and 150 mains
idle jet at 55 ok lean a little \
your should be 4.5 turms out at the start
this all assumes the chokes are stock 32mm

Hi Carlo I have checked all of the jets and tubes and found the air correctors to be 240.
I will go with your recommendations but what effect would 240 have?

[carlo rossi]

240 is too lean pollution stuff
go the recommended settings dont play with other bypasses it will create hell

[fazersix]

With a bit of patience and the use of a Dremel type tool I was able to remove the collar and re-slot the screw and was able to remove it with a screw driver. The thread turns out to good, so the binding must have come from the o-ring/spring!
Now to strip the carbs & clean and replace the carb mounts.

[fazersix]

Hi Carlo
I just received the jets but I ordered mains 155 instead of 150. Do you think this will be too rich!
Also you said the idle jets are a little lean at 55 what would you recommend?

Cheers

[carlo rossi]

no should be ok
we can adjust that out if needed
so the stack should be 210 ,77772.8 , 155

[fazersix]

Yes that's the stack, thanks.
In the middle of a full carb clean out!

[carlo rossi]

whilst they re off
whats the condition of the rubber mounts are they cracked
also if you have them out the next step is to change the auxillary venturi to 34mm from 32
but you will need 58 idles for that

[fazersix]

Hey Carlo,
The mounts certainly had a fair bit of cracking on the outside, I didn't examine that much since I was changing them any way!
New ones are fitted and ready for the carbs.
I did not take the venturi's out so left the 32mm in - that will be a later project.
I have the carbs assembled and testing the pump volume.
Do you know the correct volume? The tag on the DLHA40H carbs say 1160360401100.
I have found some info on alfabb that say 20 sots per port 7-9 cm3.
So total of 40 shots should give 7-9cm3 total out put or 3.5 - 4.5cm3 per port.
Does that sound right?
I have the floats at 14.5mm and will check the fuel level is 27mm (so I have read).

Cheers

[bonno]

I have attached a link to a recently uploaded video that might help. The first part of the video is for bench testing fuel discharge rate (40 pumps should give 14-16cc) and the second part involving on car tuning. Please note this is specific to the 1300 Nord engine, but are the same from my experience on servicing the twin Dellortos on my Alfetta GTV 2.0L, particularly for setting of idle mixture screws and balancing. Apart from internal cleaning of carbs, the fitting of service kit will ensure you will get the best possible result.
https://www.youtube.com/watch?v=eKEqqimaF3M

[fazersix]

Thanks Bonno I have watched a lot of Scuderia's video's.
His video is consistent with an alfabb post that has pollution model carbs 'H' which I have are in the 7-9ml per port = 14 - 18ml total for 40 pumps. My first result was around 12ml, after a slight adjustment I now have 16ml (8 per port), which looks good!
I have attached the document!