Mech. Speedo ratio's, Spider Euro gauges wanted

["Dean W. Cains" <dwc@domain.elided>]

Hi Group:

In an effort to 'Italianize' my '74 US Spider, I'd like to change (among 
other things) all the gauges to those that feature Italian text and 
European measurement units.  I've already got the 3 small gauges (benzina, 
olio and acqua), but I still need a speedometer (km) and tachometer 
(giri).  My question concerns the calibration for the speedometer (notice 
that I didn't say accuracy).  What determines this?  Alfa has used various 
rear axle ratios for different model years and maybe also for different 
markets.  Is it the speedometer itself that has to match the rear axle 
ratio, or does the speedo drive gear in the transmission have to match the 
rear axle ratio?

Also, what triggers the later (pre-'85) electronic tachs?  Is there just a 
connection to the ignition coil?  I ask because one of those may be easier 
to find, and they are just marked 'x 100', with neither 'rpm' or 'giri' on 
the gauge face.  Any chance they're any more accurate than the cable-drive 
tachs?

Anyone have any of these 'Italian/Euro' gauges for sale, in reasonable 
condition?

Thanks for any info you all might have to share.

Regards,

Dean W. Cains
Lutz, FL
'74 Spider Veloce (the Spica iniezione stays put, and is more than 
Italian-enough for me)
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