On 25 Nov 2005 at 13:42, Cameron Rooke wrote:
> Yes, it's a MK3. And it is a mechanical tach.
Randall's point, I believe, is that irregularly timed electrical
pulses can cause an electic tach to misbehave. Floating points or
badly out of spec dwell could cause this, as could loose wiring or
ground behind the dash. However a mechanical tach isn't susceptible
to this. A sticking cable might make the tach jump in much the same
way that a speedometer can bounce. But the dwell angle (point gap)
won't have anything to do with it, and worn dizzy shaft bushings
probably won't either unless maybe possibly perhaps they cause a
really bad gear fit. It's hard to imagine a mechanical tach hitting
12,000 for any other reason, unless your clutch slipped and the
engine really took off, in which case I'd wonder that something
didn't break.
--
Jim Muller
jimmuller@rcn.com
'80 Spitfire, '70 GT6+
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