My 1965 122 has a B20 engine from a 1969 and has been upgraded to the 1975 240 electronic ignition system. What would the correct timing be for this setup?
Thanks,

10 degress before,at 700 rpm's

Whenever timing, you should also check the timing at speed to see if the distributor is giving you the proper advance at higher rpm. Since you do not do most of your driving at idle, the timing at normal operating speeds is more important to overall performance.

John
V-performance.com

Quite right about the effects of the advance. If your using the old B18 cast iron dist & SU's, you should lower the idle speed to 700 as noted, set at 10-12 deg, then set the idle up to about 800-900 rpm where the engine timing will be somewhere around 16-18 deg if the centrifigual advance is working properly. If there's a vacuum advance on your dist, plug it, then do the above setting.
I always like to take the dist apart and clean the advance mechanism before I set the timing.
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'89 245 sportwagon, destroyed by hit & run driver, RIP. '04 V70 2.5 T Sportwagon, 12k mi and '91 245 5-speed, 209k mi, replaced the '89