Correct timing for 912
 

Hi,
Am going to set the timing on my '69 912, the manual says 3 degrees BTDC. Is this still good despite using unleaded fuel or should it be retarded. the fuel here is invariably 95 octane ( and damn expensive)

For the US listers, note that 95 octane in Ireland is NOT the same as 95 octane here in the US. Ireland, along with the rest of Europe, uses RON as their measure of octane. The US uses the average of RON and MON, which always produces a lower number. 95 RON is roughly 87 octane by the US measure.

To answer the actual question, I'd stick to the original timing. If you're not hearing any pinking, you're not advanced too much, and you're likely close enough. If you are hearing pinking, then you do need to retard the timing, but not necessarily over the whole range. Engine condition and the exact state of tune matter as much (if not more) than the octane of the fuel you're using.

Timing really depends on the distributor you are using. Which do you have?