Hello

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Vyt
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Hello

Post by Vyt »

Hello,

I am a long time racer and alfa enthusiast. I'm pretty up on fixing and rebuilding GTV 105s, but GTV6s are new to me. I recently sold my 1966 Giulia Sprint race car and bought this 1983 GTV6. It turned out to have many issues... looking for lots of help and advice.

-I have a set of FRPA dellorto carbs that seem to be leaning out. I have damage two pistons, a liner and a full set of plugs that had melted. This happened on the first session of the first day on the first lap...so i've never really had a chance to actually drive this car.
buyer beware i guess? Now I'm determined as ever to make this car right..

Thanks
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SydneyJules
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Location: Sydney

Re: Hello

Post by SydneyJules »

Car looks nicely prepared and lightweight- I'm guessing it's a 3.0?

Once your rebuild is complete, I believe it's worth having someone tap the exhaust collectors for wideband sensors so that you can fine tune fuelling with accurate knowledge of air fuel ratios so you can see which banks are not running well- sounds like you've leaned out fairly severely. I would definitely consider some dyno time.

Is the ignition run on the factory advance?

You should definitely purchase Jim K's book for advice on modifying the distributor curve.

Or look at fully programmable injection- or at least the ignition side of things.
Fixing it bit by bit....

Vyt
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Re: Hello

Post by Vyt »

Thanks Jules!
Yes, the car is getting light and getting even lighter. over the winter i've gutted the doors, removed the wiper motor and all sound deadening. The car does have a three litre, which could be causing some of the leaning out issues.
yup, Ive bought a wideband 02 and have rebuilt the carbs, documenting all settings and jets.
yes, the ignition is running on factory advance.

KevinR
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Re: Hello

Post by KevinR »

Hi . I can't see clearly but your fuel pressure regulator should be on return line which is bottom row of carbs . This stops you from running out of fuel but you must set pressure correctly otherwise you will overflow float chambers and get hydraulic lock and conrod out side of block . More than likely those are 2.5 carbs in standard form but you can get mains drilled out . The 3.0 carb SA model already had bigger mains fitted to the 2.5 carbs .
Let me know

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75evo
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Re: Hello

Post by 75evo »

Hi VVT,

Do you have more photos of your belt system? The tensioner in the middle of the Vee looks good.

Vyt
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Re: Hello

Post by Vyt »

Good to know, ill switch the pressure gauge around. What pressure do you typically run with these carbs?
Yes, the Mains have been drilled out from the stock 130, needle float valve is 120..The venturies/chokes have been modified too, around 40mm. Is there a list of recommended modifications for these carbs to run with the bigger 3.0?
Thanks again.

Once the engine is put back together. I'll' post some pictures of the tensioner.

KevinR
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Re: Hello

Post by KevinR »

Hi . Very very Important you have correct pump for these carbs because if you have a high pressure pump from an injection model and you now put the fuel pressure regulator in the correct position on the return line YOU will be rebuilding a new engine again - due to hydraulic lock ( floats can't close off fuel supply ) .
I have post a pic of the fuel pump that Alfa Romeo fitted to all the GTV 3.0 carb cars in SA and this is same pump we race with delivering up to 270hp . Just when you think it's simple you will find Bosch no longer make this pump under this number so they have supplied a chart showing what it's new part number is . This I have attached a pic of as well . This new pump is 100% identical with same fittings in and out . Note its delivery fuel pressure which cannot by pass the needle hence the reason Alfa use the regulator to back it up . You could have possibly blown your lost motor due to fuel starvation .

The original part number on the carb GTV Bosch pump is 0 580 463 014.
Bosch has listed it under new number as in the chart attached to 0 580 464 070 . Look in the tables in the second picture third column row five then it's cross reference .
I double checked this as delivery pressure must be 300kpa and the size of inlet to be 12mm and outlet to be 8mm .in the First pic attached and we currently use this pump .
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Vyt
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Re: Hello

Post by Vyt »

Hi Kevin,

Thank you very much for taking the time to find the information, and post pictures of your Bosch fuel pump.
I'm currently running a holley race pump 1-4psi. Could this still be used? or is the size of the inlet and outlet crucial?
Its nice to know that these cars with the downdraft dellortos can be potentially capable of this kind performance..I'll be picking your brain on the specifics of your engine very soon :D ..I'll snap a few pictures of my current set-up. and i really appreciate all the information so far.

Vyt
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Re: Hello

Post by Vyt »

can anybody tell me what spark plugs are best suited for a 3.0 12V with Frpa carbs..??
Thnaks !

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