<VV> Advice needed on throttle shaft repair

[Mark Durham]

Charles, generally speaking, the harder shaft will wear instead of the
carb base, but it will wear as well. If you decide that the shafts are
leaking, AKA, use Matt's method, the engine will speed up if it gets
any of the starter fluid past the shafts, I would suggest that you do
both new shafts and the o-ring kits, to get a good seal. After all,
these carbs are 40 something years old. But, I ran the original carbs
220K miles back in the 60's and 70's, so its not a real big issue.

That probbably should do it, if that is where the leak(s) is. Also,
take a look at your spacers under the carb, and the gaskets, they tend
to crack, and make sure the crossover tube is tight with clamps on the
carb nipple and the crossover on both sides, then check for leaks at
the hose for the vent valve. It could be leaking anywhere.

Also, the engine going down in RPM by itself could be just a re
rigging problem. Have  you made sure that both throttles are sitting
on the throttle adjustment screw at the 600 RPM then set up the
linkage from there? Its very easy to lift one or the other when
adjusting. I've done it all, and had the same problems. Good luck.
:):)
Mark Durham

On Tue, Feb 22, 2011 at 12:29 PM, Charles McKinley
<cmckinley313 at verizon.net> wrote:
> Is there a methodical way to check whether my throttle shafts are worn
> to the point where I need to replace them? As far as I know they're
> still the originals on a '63 Monza 80 hp with about 80,000 miles on
> the clock. It appears from Clarks catalog that I have a couple choices:
>
> 1) try a set of their throttle shaft seal kits and keep my existing
> shafts (assuming they're not too worn);
> 2) buy new shafts;
> 3) maybe 1) + 2)? (i.e. new shafts plus seal kits - or is this
> overkill?)
>
> The symptoms that lead me to suspect worn shafts are
> 1) difficult to set and maintain a steady idle at ~600 rpm.
> 2) sitting at a stop light, the idle speed tends to slowly decrease
> from, say, 1000 rpm to ~500 rpm.
> 3) Difficulty balancing carbs with Unisyn tool - the mixture and idle
> adjustments don't behave as they should. In particular, the mixture
> screws can be anywhere from 1.5 turns out to 5 or 6 turns out with no
> difference in the engine speed.
> 4) I've observed gas leaking from the throttle shafts onto the
> manifold, and it seems like this is a pretty good hint.
>
> Advice will be most welcome!
>
> Thanks in advance,
>
> Chuck McKinley
> '63 Monza 900 3-speed
>
>
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