Hi Gary:
I hadn't previously seen any mention of the "hot day, high tach reading"
syndrome anywhere. Thanks for bringing it up-I thought I was the only
one with the problem and assumed that the guys who calibrated it had
made a mistake somewhere. And, of course, I've been too lazy to call
them and ask about it, but it's been really weird to drive the car and
after a while the tach starts reading higher and higher--with no
corresponding increase in road speed.
Regards
David Sosna
garywinblad@attbi.com wrote:
>
> Good work Doug!
> Until you put a hole for adjustment, there NEVER is one.
> Yes, the control is VERY sensitive.. and with vibration,
> it WILL change. And the top end is always the problem,
> you will probably notice on hot days, it will read very
> high, conversely I guess, on cold days it will read
> low.. so do your drag racing on hot days so you don't
> over-rev ;-)
> Gary
> > I got around to calibrating my tachometer today. I had expected there to be
> > a rubber plug over the calibration potentiometer, but on my car, the tach
> > has no opening that allows access to the adjustment.
> > Fortunately, the cover came off the tach easily and I was able to remove the
> > tach from the housing and calibrate it to a diagnostic tachometer. This gave
> > me the chance to clean inside the lens, so now my speedo & tach are clean &
> > all the other gauges look dirty.
> > So, there I was, holding the innards of my tachometer in my hand while it
> > was connected to the cars wiring harness with jumper wires. I felt like a
> > heart surgeon.
> > The adjustment is very sensitive, it takes very little turning of the
> > potentiometer to make a large change in the reading.
> > I set it at 3000 rpm, and so far it seems pretty close, but I did see that
> > at higher rpm the diagnostic tach was reading higher then the car's tach,
> > about 4150 at an indicated 4000 on the cars tach. I did not check any higher
> > than 4000.This may not be a real issue, as my valve gear should be good for
> > over 6000 rpm & the tach only reads to 5500.
> > I hope my pistons are good to 6 grand too ;-)
> > I will be out with the Tiger tomorrow for the Woodward Avenue Dream
> > Cruise, are any other listers planning on being there?
> >
> > Happy Motoring
> > Doug Leithauser
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