Mark, actually there is a calibration adjustment on the back of the gauge. I
estimated the rpm for now, until I find someone with an accurate mechanical
gauge to check it with. Seems to be about the same readings at exact mph as
the gas tach read. I'm not sure about the tachs being the same, but there
sure is a wide range of adjustment on the gauge, varying from where it is
set now by at least 1000 rpm each way. So I think it should work just fine
whatever the ratio.

Karl

>-----Original Message-----
>From: Mark Drillock <drillock@earthlink.net>
>To: thewestyman@MINDSPRING.COM <thewestyman@MINDSPRING.COM>
>Cc: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON.COM>
>Date: Friday, April 02, 1999 3:49 PM
>Subject: Re: Success: tachometer in my TD Syncro Westy!
>
>
>>Hi, Karl. What have you done to calibrate the tach for the pulley ratios
>>in the Vanagon application? Have you calculated the difference of the
>>alternator speed vs engine speed in the Jetta as compared to what you
>>have now? Do you know if all of the VW Diesel tachs assume the same
>>pulley ratios? Thanks for any info as I hope to put a tach in my TD
>>Westy soon.
>>
>>Mark