Hi Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
dklawson
Yoda
Offline
The RVI models are the Smiths tachs that don't like electronic ignitions. The RVC are generally OK and simpler to hook up.
EDIT: VDO does have several possible donor tachs and they routinely show up on eBay. I noticed something while working on several of the RVC types having the needles with chromed hubs, their scales aren't uniformly spaced. This means you can sort of calibrate them if you transplant a complete VDO into the case but you'll have some degree of error across the span. Most VDOs are linear apart from the very bottom of their scale. I got VERY good results using the aftermarket electronics to power the original D'Arsnoval movement of the RVI tachs. I added a parallel trim pot to the movement's connection to the electronics. This kept the original needle and the movement designed and balanced for it. The results were much more linear across the span than transplanting the whole movement and sticking the original Smiths needle on. This is discussed in more detail in the PDF.
EDIT: VDO does have several possible donor tachs and they routinely show up on eBay. I noticed something while working on several of the RVC types having the needles with chromed hubs, their scales aren't uniformly spaced. This means you can sort of calibrate them if you transplant a complete VDO into the case but you'll have some degree of error across the span. Most VDOs are linear apart from the very bottom of their scale. I got VERY good results using the aftermarket electronics to power the original D'Arsnoval movement of the RVI tachs. I added a parallel trim pot to the movement's connection to the electronics. This kept the original needle and the movement designed and balanced for it. The results were much more linear across the span than transplanting the whole movement and sticking the original Smiths needle on. This is discussed in more detail in the PDF.
