I would like to know how to change from a single point distributor to an electronic distributor in my Datsun 620 w/ L20 engine. Thank you.

 All you have to do is get a distributor from a 79 620 Pickup, complete with mount, drop it in, connect the wires, and you're rolling!  I've done it on 510s and both 521s I've owned in the past. 

from what I've been told:
[quote]'77-78s used that remote ignitor box[/quote][quote]'79-84 used the matchbox type[/quote][quote]
all from the datsun L series motors...

[/quote][quote]everyone asks how to hook them up so here is the way:

 [font=Arial]The + side of the EI coil is wired to the "B" terminal on the matchbox. Letter "C" on the matchbox is wired to the - side of the coil.[/font]

[/quote][quote]ANY of the L series pedestals will physically fit, they bolt right on, but there are A LOT of different timing variations. The plug wires CAN be rewired to compensate for a wrong dist/pedestal combo, but ya gotta know what yer doing!
[/quote]

Thanks for making that clearer  than I  did.  I meant to say 79 and up rather than just 79.  I've used the earlier ones with the remote box also but they are a little more tedious to wire in.  If the new pedestal lines up the distributor differently than the stock one, just make sure that you pull the stock one with the rotor pointing at #1.  Then wherever the rotor is at when you install the new one will be number one then simply install the other leads in the proper firing order.  You'll also want to get a coil for electronic ignition and eliminate the ballast resistor.  I used a 280Z coil in most cases.

If I remember right the 620 also had a heat or speed activated mechanism that would not let the second set of points kick in until temp or speed was reached. I'm doing this from memory so I don't remember which it was. IMH do you remember? You may want to locate that and disable it. Also you can also buy a Pertronics conversion kit and drop it into the distributor. When I had my 620 I always ran it on one set of points. Got it right after my wife and I got married. It ran like crap even after I invested in a new carb. I ran it like that for two years then decided to rebuild the engine. I was amazed, I had been running it with a valve that had a chunk broke off of it the size of my thumb. Those were tough little trucks and a lot of fun in the snow! More fond memories.

I don't recall that about the distributor but I did my conversions on 510s and a 521s.   If I recall, my 620 had a single point distributor.