Smiths copy tachometer

[PeterR]

Hi from the Antipodes! Interesting discussion regarding Smiths instruments, thank you. My 1970 A65 is very original in most respects, but I think it has the incorrect tacho, which optimistically asserts that the engine is operating at a higher RPM than it really is.  The ratio marked on the tach is 4:1, but it seems that 3:1 is the correct ratio?  It doesn't bother me too much as my focus is listening out for nasty engine noises, but I assme that the remedy would be to look out for a 3:1 item?
BTW, I have been able to install a positive fixing for both the tacho and speedo using SS coupling nuts, M5 bo;ts & 'top hat' grommets.  This has probably already been done by others, but happy to provide more detail if required. 

[limeyrob]

Yes you need a 3:1. This was a common error as the Triumphs used a 4:1 and people would get a used tacho and assume it would be OK.