Hello all,
This is the first time I've submitted to this list, although I've been
following it for a few weeks. I'm enjoying much of the discussion.
Any thoughts on this one?
The speedometer in my Series 5 became unsteady. I replaced it with one of
my spare speedometers, which seems to be working fine.
However, while testing speedometers, I discovered that my tach may be
inaccurate; it seems to indicate a higher RPM than the actual RPM. The
puzzling part is that it seems to get worse (less accurate) after driving
the car for a while (hot engine). What I'm referring to as "actual RPM" is
from a Tach/Dwell meter. To be honest, I have no reason to believe that
it's particularly accurate. However, RPM indicated by the Tach/Dwell meter
and MPH indicated on the speedo are consistent with calculations based on
overall gear ratios and tire circumference.
Tach/Dwell Car's tachometer (RPM)
tachometer
Initial driving, After driving a while,
cold (cool) engine hot engine
1500 1200 (80%) 1120 (75%)
2000 1640 (82%) 1500 (75%)
2500 2080 (83%) 1920 (77%)
3000 2510 (84%) 2370 (79%)
I tried two other well-used Series-5 tachs; they also indicate
higher-than-actual RPM's, although I don't know that the inaccuracy varies
for these. (I didn't test them to that extent.)
I was wondering if this was typical of these tachs; has anyone else noticed
this problem?
It's really just an annoyance; I'm not sure that I'll worry about it too
much. I'm just happy to have this car back on the road.
-------------------------------------------------
I've also discovered that I have some extra instruments that I'm willing to
part with. All are Jaeger instruments. They're all of same style. The
lettering is distinctly larger and blockier than that of Series-5
instruments. I'm guessing that they are from an earlier model Alpine; I
think I acquired them with a parts car - an Alpine with more conspicuous
fins. The descriptions may help someone figure out the application(s). I
have ...
2 Speedometers
0 to 120 MPH
both have identical markings
"SN 5324/16 1000"
2 Mechanical tachometers
0 to 6,000 RPM
red lines at about 5400 and 5600
both have identical markings
"X 100
3.21-1
RN 1316/00"
2 Water temperature guages, 120 to 250 deg. F
3 Oil pressure guages, 0 to 100 LB/0"
1 Fuel gauge, 0 to 11 gallons
E-mail me if you're interested.
Jon
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