Jim,
I just took one apart, and I can find no allowance for adjustments
whatsoever. They may be preadjusted at the factory by the tension on
the spring inside.
Joe Curry
jaltman@altlaw.com wrote:
>
> Thanks for the reply. I am still just trying to identify why the tach
> readings jumped so much just changing the tach cable. Your thoughts on
> adjustment are appreciated, but a question: Are there adjustments on the
> tach and speedo to calibrate? where?
>
> Jim Altman jaltman@altlaw.com Illigitimi non Carborundum
> http://www.altlaw.com/ 69-TR6#CC28754L W4UCK
>
> -----Original Message-----
> From: Ken Streeter [mailto:streeter@sanders.com]
> Sent: Saturday, February 21, 1998 8:40 AM
> To: Jim Altman
> Cc: 'Triumph List'
> Subject: Re: Tach Question
>
> jaltman@altlaw.com wrote:
>
> > Lets try this again. Would one of you 6 drivers please note
> > your tach reading at 60 MPH and let me know what it is?
> > Please. No OD.
>
> Jim,
>
> I'm sorry that I didn't reply the first time, but one of
> my TR6s in in winter storage, and the other is awaiting
> a new transmission.
>
> From my recollection of many hours in the TR6, the RPMS
> in 4th gear is very nearly 500rpm per 10mph. Within the
> accuracy of my speedometer and tach, I would see 3000rpm
> at 60mph. Actually, I seem to recall that on my car, the
> tach reading is slightly more than 500rpm per 10mph in
> non-OD 4th -- more like 3150rpm at 60mph.
>
> You can also find this figure in the Bentley manual on
> page 44. There is a chart for "Effective Gearing" giving
> "Engine speeds (rev/min) at road speeds of 10mph and 10kmh"
>
> It indicates 482rpm for 10mph (US-spec cars) which would
> be 2892rpm at 60mph in non-OD 4th gear. The same table
> also indicates 20.7mph per 1000rpm, which means 3000rpm
> would be 62.1mph. This differs from what I see in either
> of my TR6s.
>
> However, the exact number is likely to vary somewhat
> depending on things like what type of tires are on the car,
> if the wheels are stock, and even how much air is in those
> tires. So I find it quite reasonable that my empirical
> numbers differ from those in the Bentley / TR6 factory manual.
>
> If you are trying to calibrate the tach, I would suggest
> instead using an external electronic tach hooked up to the
> distributor to calibrate. You can do this in your garage.
> If calibrating the speedo, the easiest way would be to time
> yourself on an officially measured mile or quarter mile (do
> you have any aircraft-enforced speed traps with quarter mile
> marking on the road?) on a road near your house. Actually,
> if you are good friends with a police officer, there's an
> even easier way! Either of those are sure to be more accurate
> than using the tach to calibrate the speedo, or vice versa.
>
> --ken
> VTR WWW Maintainer -- http://www.vtr.org
> '70 & '74 TR6 Daily Drivers (well, 8 months per year...)
>
> --
> Kenneth B. Streeter | EMAIL: streeter@sanders.com
> Sanders, PTP2-A001 |
> PO Box 868 | Voice: (603) 885-9604
> Nashua, NH 03061 | Fax: (603) 885-0631
--
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