I have recently bought are really pristine 52mm (2") vacuum gauge with the
typical Smith's black dial consistent with the 100 instruments. I am thinking
of putting in a three-gauge supplemental panel, using new Smiths guages from
Holden. There are a few technical and aesthetic questions which I would
appreciate advice on:
1. VACUUM GUAGE. The 1/8" feed pipe must by necessity be fed off the
manifolds vacuum. Which alternative would you prefer:
a. Holden sells a thin 'spacer' for the 4-bolt H6 manifold, which
appears will fairly line up and not be significantly thicker than the stock
spacer. It has a 1/8" barbed male connection built in, so you do not have to
drill the manifold. I could either mount one, or if there is a thickness
difference, mount 2, and 'T' them together with a connecting hose, and run
hose to the gauge.
b. Alternately, they sell a 1/8" T connection for copper. Could I put
the T in the vacuum advance line to the distributor? I am assuming, maybe
incorrectly, that the vacuum in this line is a relatively static value, and
rises over a matter of seconds with engine load, and that putting an
additional 2 feet of vacuum line on the system would not radically affect the
input to the vacuum advance. This is a more attractive alternative in terms of
keeping the gauge connection out of sight, but can I do it without screwing up
the advance?
Also, if I locate another Smiths vacuum, could it be used to monitor
carbuerettor synchronization? I.e., is manifold vacuum a sufficiently accurate
way of reading the piston lift in the SU's that you could use it to keep the
carbs in synch? range is 0-30 in Hg.
2. There is a great looking 2" (52mm) Smiths black dial quadrant type
ammeter that reads +/- 30A, with the traditional V bezel. Is this range okay
for the 100's generator? Were these gauges originally shunted, or does Smiths
ammeters have internal shunts.
3. I am looking for an old 2", preferably Lucas or Smiths, voltmeter
without the battery 'pictogram', to go along with the vacuum guage and ammeter
in a three-gauge panel. If anyone has a line on where to find an old one or a
NOS gauge, I would appreciate it. (I would abandon this if I locate another
vacuum guage and there is a legitmate reason to have to vacuum guages.
4. My thoughts on mouting the panel are either to suspend it with a bar
clamped to the choke cable bracket, or to mount it against the center vertical
panel on the tunnel. Any suggestions?
Answers to any of the four, or other thoughts very much appreciated.
Allen Miller BN2/M
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