Nathan,
this sounds alot like the problem I had with My 1600 carbs. I couldn't get
the idle below about 1200 RPM except when I pushed on the linkage. (As with
yours, my throttle Cable also had plenty of slack). My problem turned out
to be with the front carb throttle plate hanging up on the side of the carb
body. The throttle plate was not completely closing- or bottoming out on
the set screws. As you described, I could not feel any perceptable movement
in the throttle when I pushed on them, but the engine idle would imeadiately
plunge when I put any pressure on the throttle linkage. I believe the cause
was do to wear to the throttle plate near the shaft. I happened to have a
spare set of carb bodies, when I swaped the front carb with my spare, the
problem went away. If you don't have a spare carb base try removing it and
buffing the carb body near the shaft. This should lessen the friction
between the throttle plate and the carb body when the plate is closing. You
could also try stronger return springs, but I don't think this a
particularly good solution.
----- Original Message -----
From: nruff <NRUFFCORN@prodigy.net>
To: datsun list <datsun-roadsters@autox.team.net>
Sent: Monday, January 10, 2000 9:35 AM
Subject: Fw: Manifold Vacuum
>
> > > Nathan
> > > Does the idle rise after the car starts warming up if it does you may
> > > have the cable to tight.
> > > nruff wrote:
> >
> The cable is loose. If this adds to the dilemma at all, if I push down
on
> both carb's throttle linkages (where the return springs are attached),
it
> sputters and dies and will not recover. When I do this, I can't even
> percieve that the throttle shafts are moving-they already feel bottomed
> out.
> The timing is currently set at 16 BTDC which also helped bring the idle
> down. There is still NO exhaust so it is difficult to judge how the car
is
> operating, and YES the neighbors still talk to me <g> !! The car seems
to
> have OK power but I haven't really gotten on it-doesn't feel like 135hp
> yet.
> I admit though, that I do "baby" my cars, trying to keep them out of
the
> higher RPM ranges. When I cruise around in my MX-6, I get passed by
> grandma's in Omni's, but I don't care. Still it's fun to blow away
> "contenders" from time to time<g>. From the sounds of the rest of the
> list,
> I may have to force my self to keep the RPM's up to really enjoy the
> spirited driving that everyone talks about-sacrifices-sacrifices ;-)
Well,
> I digress.
>
> Thanks again for your input.
>
> Nathan
>
> > > Hey all!
> > > >
> > > > BTW, thanks for all your responses on my many questions during this
> > rebuild,
> > > > it has been a learning experience to say the least. I have very
> limited
> > > > time and access so the restoration has been a drawn out process but
> > > > hopefully I'm closing in on it.
> > > >
> > > > After your advice on my 2L, I was able to take the vacuum line OFF
the
> > > > manifold port and place it ON the carb vacuum port. Made quite a
bit
> of
> > > > difference <g>. I am still experiencing a higher idle than I
perceive
> > to be
> > > > acceptable. I can't get it any lower than about 800 rpm. Even
after
> > > > screwing the idle adjust screws all the way out, the motor will not
> die.
> > > >
> > > > The intake vacuum @ 1000rpm is approximately 18-20 in-HG. Is this
> > > > acceptable? I am fairly certain I am not leaking around the
insulator
> > > > blocks and the carbs are brand new Z-therapy rebuilts (is that an
> > oxymoron?
> > > > <g>). Are there any other ports on the intake or carbs that could
be
> > > > leaking or do any of you have other possibilities?
> > > >
> > > > Thanks!
> > > > Nathan
> > >
> >
> >
>
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