Re: GTV 2000 carb Q's

[Simon Favre <simon@domain.elided>]

Jeff Matson wrote:

>OK, bet you've never heard this one before:
>I've got a '74 GTV 2000, long ago converted to Weber DCOE's (early 80's
>based on records I have).  The puzzler is that the records I have
>mention that the car has a 1600 intake manifold.  
... {SNIP}

>1.  Can this really be true?  1600 intake m'fold on a 2000?

The intake manifold gasket is the same on all Alfa inline 4's from the
Giuliettas to the last of the US 2000's. I don't see why it wouldn't
work, tho it was probably more work to install due to linkage 
differences.

>2.  Would it be worth my trouble to try and locate a 2000 intake
>manifold and make the switch?  I assume I'd have to then change most all
>of the jets and such in the Webers.  Any thoughts on where to look for
>such a part?  How could I identify what m'fold is on the car now?

If it works, I wouldn't bother changing it now. The way to identify
what you have now is to look for the thermostat. Look at the upper
radiator hose. If it comes out of the manifold casting with no sign of
a thermostat housing, you have a 1600 manifold. That thermostat screws
into the end of the manifold casting. If the upper hose comes out of
a more traditional bolted on thermostat housing, you have a 2 liter
manifold and the receipts are wrong, or the whole story hasn't been
told. What kind of air box does the car have? Most likely, it's a
Euro air box. If that's the case, I don't see why they wouldn't use a
Euro manifold for the carbs.

>3.  I can't sort out with much certainty what's in the carbs now. 
>Original setup had 30mm venturi, 50F8 idle jet, 135 main jet.  I believe
>it now runs a 125 main jet (last records show this change).  I do have
>notes from the P.O. showing some chats with Weber people, but I don't
>know if he ever had anything done or not.  Can anyone comment on whether
>these make any sense?

The jet sizes are pretty easy to identify. Under the little round cap
with the wing nut, you will find all the answers except one. ;=) The
size of the main venturi can only be determined by removing the air box,
the outer part of the venturi, and then the main venturi from deep in
the carb throat. On the jets, there is a stamped part number for the
main jet, the emulsion tube, the air correction jet, the idle jet, etc.
You might want to pick up one of the standard Weber books: the one by 
Passini, or the Haynes Weber manual. They show you how to identify each
part, and what the number ranges are. 

>4.  Am I better off keeping my fingers the hell away from the Webers and
>just driving the car?  That's sort of my inclination right now, but if I
>could get a decent performance improvement by getting the correct 2000
>intake stuff fitted I might make a good project out of it.  I'm good
>with this sort of stuff, just never touched carbs before.
>Any tips/input are greatly appreciated.

If the motor is fairly stock, there is a decent set of jet sizes that can
be installed with relative ease. You just need to check ALL the part #'s
that are in the car first and ask again when you have the real numbers.
If the car has good power and the plugs look normal, I wouldn't mess with
it.

BTW, when I put Webers on a 1750 for my '67 GTV, I kept the 1600 manifold
and air box that was in the car, rejetted the carbs and changed the main
venturis. The venturis were the most expensive part.

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