Hi All!
I have recently removed the air pump, gulp valve, etc from my 72 GT. Now, the
only
thing hanging off of the intake manifold is the vaccuume advance for the
distributor.
At idle, the vaccuume advance is acting like a speaker and humming (buzzing?)
My
guess is now that the gulp valve is no longer attached, there is a stronger
linkage
between the intake manifold pressure and the vaccuume advance. If I remove the
vaccuume
tube and place my thumb on it I can feel the thupa thupa thupa on top of a
constant
vaccuume. (Electrical analogy - a sine wave riding on top of DC.)
I placed a timing light on it and did not notice the timing jumping around, so
I am
guessing that the magnitude of the variation in pressure is not enough to
change the
actual advance. However, the noise is annoying, and it doesn't seem like it
would
be good on the vaccuume unit.
Has anyone run into this problem? My guess is that I need the equivalent of a
low
pass filter. Either a large vaccume resivoir, or perhaps a restriction in the
line.
Any ideas?
Thanks!
Dave (waiting for a new MG in the states) Hall
http://www.pacifier.com/~dlhall
72 MG BGT
74 Midget
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