I fought the same battle for a long time. The tach was off by 50% high.
Turned out that replacement cables that were slightly too long had
compressed the magnet too close to the pan inside the tach. Took the thing
apart and pressed the magnet back onto the shaft and all was well. I have
some photos and description of my repair on my tr web page (page 3).
Jim Altman jaltman@altlaw.com Illigitimi non Carborundum
http://www.altlaw.com/metro/jaltman.html 69-TR6#CC28754L W4UCK
-----Original Message-----
From: owner-triumphs@autox.team.net
[mailto:owner-triumphs@autox.team.net]On Behalf Of
Scott.Mackay@intl.sematech.org
Sent: Wednesday, September 16, 1998 10:39 AM
To: triumphs@autox.team.net; paradise@icx.net
Subject: TR6 engine speeds
Whoa there Brian,
4500 RPM at 70 MPH?!?!? After grinding numerous tire sizes/gear ratios
through
my spreadsheets, I would challenge something is very wrong with a TR6
indicating
these numbers. A stock '6 (e.g. stock size tires, stock 3.7:1 diff) will
only
be turning ~3250 RPM at 70 MPH, in top gear, no OD. At 4500 RPM, you should
be
rocketing at 97+ MPH. I would suggest double checking your numbers. If the
needles still indicate what you said, line up next to the family grocery
getter
to verify you speedo is accurate. If you speedo turns out to be accurate,
your
tach must be way out. These cars are notorious for having the incorrect
speedo/tack unit installed.
Scott Mackay
Austin, TX
(now turning 3500 at 75 mph regularly!)
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