Mike C.----I can't tell you if or where you might have the vacuum leak
that you suspect. There are a couple of points that have been offered to
you that is open for debate.
Meanwhile, you should have vacuum present at the retard capsule, at idle
speeds only, IF the vacuum line is connected to a port on the carburetor
downstream of a closed throttle plate.
If you have no vacuum present at the distributor, follow this line back
to its source. A functioning retard will change the timing by as much as
16 deg. (i.e.12 deg. BTDC to 4 deg. ATDC) and slow the engine down
approx. 500 rpm.
Conversely, if your engine speed has been set by carb adjustment only,
with no vacuum retard in operation, there will be no change in speed if
you pull this line off the retard capsule.
I haven't ran with the thermostatic switch in the top hose for some time
now, so I'm not up to speed on how this works, entirely. I do remember
at when the coolant got to a certain temperature, the switch would
interrupt this vacuum, and cancel the retard. We know this interruption
of retard speeds up the engine by allowing the timing to increase by
several hundred rpm.
Here's what I'm not so sure about...If it is necessary for the coolant
to get up to a certain (normal running) temperature before the switch
opens up the retard line, this would cause the engine to idle much
faster than normal, as the coolant is warming up. (Just as if the retard
was canceled by coolant being too hot) I don't remember this ever
happening. Once the Choke knob was pushed home, the engine speed would
idle around 800 or so, even with the gauge reading about 120 deg.
So, based on old memories and what I believe should happen, the only
purpose of the thermostatic switch is to cancel the vacuum retard during
times when the engine was idling, and too hot. I welcome discussion
from those who find it differently.
Dick
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