Many carbureted cars had a cushion in the throttle linkage. The purpose
was to prevent the throttle from closing completely when lifting off the
throttle. Closing the throttle too rapidly, would cause excess vacuum and
would suck too much gas through the idle circuits. The car would often die as
a result.
But I do not remember any such device on the Euro carbureted
Alfas, nor do I remember anything in the Weber its self.
So in some
respects, what your Alfetta is doing is reasonable. But it should drop to
about 2000 rpm and then gradually creep back to the idle setting.
I
suggest you lubricate the throttle linkage, specifically the bell crank the
changes the direction of the linkage to the Webers. The L Jetronic spiders
are notorious for the bell crank rusting up and locking the linkage. In fact,
the L Jetronic linkage can be adapted to work nicely with Webers.
All of
our USA version Alfas had a cable running to the top center of the Spica
manifold. You mentioned a cable linkage on your Alfetta. Are you using part
of the Spica linkage to work the Webers? If so, I suggest removing the bell
crank at the front of the cable to clean and grease the pivot. And use
powdered graphite on both ends of the cable.
I just checked the linkage
on an Alfa engine with Webers in my shop. It has the Spica modifed for
Webers. The cable activated bell crank seems to move. The linkage is stuck.
Or maybe the throttle shafts are stuck. The engine has sat for some years.
Biba, I suggest you lubricate all you throttle linkage connections. Maybe
use penetrating oil so it works into the cracks and clearances. If that
helps, maybe tear it all down and use grease.
To see if the distributor is
really returning to static timing, put a timing light on and watch the
advance. The timing should advance smoothly as you open the throttle. I
should return rapidly to static when you back off the throttle. I used to
grease the advance weights as they can get rusty and hang up.
Ciao,
Russ
Neely
________________________________
From: AlfaCyberSite
<[email protected]>
To: AD <[email protected]>
Sent: Fri, February 12, 2010
9:13:48 PM
Subject: [alfa] Unintended Alfa acceleration
Nope, Toyota doesn't
have a corner on the market. Okay, the problem is/was the engine revving high
when slowing down. First it only went up to 3K, then when it started going to
4K+, I turned around and came back to my shop. I'd stopped along the way to
see if the accelerator cable was pulling out. Using my anemic needle nose
pliers it didn't seem so.
Weird part is just as I was turning into the
driveway, the idle went down to normal.
'75 Alfetta GT; Nord; Weber 40
DCOE's; Euro inlet manifold, etc.; MarelliPlex
Cable was tight, but tightened
it a tad more.
Throttle shaft/unit not hung up
Nothing missing on the inlet
manifold
No cracks on either the distributor cap or rotor
Springs in place on
the mechanical distributor advance
Distributor tight - doesn't rotate
Biba
Irwindale, CA USA
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