scott suhring wrote:
>
> Tim:
>
> My sense (please, those who REALLY know provide a definitive answer)
> from looking over the by-pass valve when installing the gaskets and
> valve was that screwing it in (to the right) caused an inner threaded
> shaft to move inward toward the valve, thus compressing the spring,
> causing a thighter fit and more vacum needed to open the valve, with
> the noticible decrease in the idle RPMs when you screw it in.
>
> Scott Suhring
> Elizabethtown, PA
> '70 TR6
>
> Tim Gaines wrote:
screwing the adjustment screw IN (clockwise) actually reduces
> > the spring load on the valve and causes it to open under less pressure.
> > Do I have this right? What I really want someone to tell me is how to
> > make the adjustment.
> > Tim Gaines
> > 1980 Spitfire
> > 1974 TR6
> >
Scott, Tim,
I've done the adjustment on mine following the outline in the Bentley
manual and it responded well. Turning the screw clockwise reduces the
spring pressure and at some point allows the diaphragm to "float"
resulting in a sudden increase in idle. To adjust do the following.
1. Disconnect vacuum retard line and plug the line. This should bring
engine idle rpm up to about 1300 rpm.
2. Turn the adjusting screw clockwise until the engine speed increases
abruptly to approx 2000-2500 rpm (indicating the valve is floating).
3. Turn screw counterclockwise just far enough to bring rpm back to
1300. Using the throttle, suddenly increase engine speed and let it
return to normal. Engine speed should drop back to 1300. If it doesn't
the valve is still floating and should be adjusted counterclockwise a
half turn at a time until you can rev the engine and have it return to
normal (1300). When you find the point at which this happens back the
screw out counterclockwise one half turn more to properly seat the
valve.
4. reconnect vacuum advance.
All this comes from the Bentley manual p. 224.
It probably would be a good idea to back the adjusting screw all the way
out as you begin to ensure that you don't start out with the valve
already "floating".
Hope this helps.
Skip Osmundsen
'76 TR6
'60 TR3A
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