replaced distributor with 2 new but can't get plugs to fire on time.

That does sound strange, core on a new part! I know what you mean about just throwing on a part and it works, like to know why! Did you try your old cap on the new dist.? They used 2 different types,think one was actually a mitsubishi, i think. Back in the day worked on a few of these, good little engine! Head gasket blown between 3&4 was common, or was it 1&2? Was doing a head job once, had a piece of heater hose stuck down between the chain to keep tensioner from popping out, buddy came in the shop saw it and pulled it out and said look at this it was sticking down in the motor! I let him know why, should have made him pay for pulling it all the way down in front to put the plunger back. Sorry for the rant, not many times we get to relay with another mechanic.

I was a GM tech until I "discovered" Toyota dealership that cared about the service dept and took care of techs etc. When I rebuilt the Nissan I had trouble keeping the tensioner in place and a much younger friend showed me your trick (sorta same way - so you can teach an old dawg new tricks!). I had the head resurfaced and the block decked because of the potential problem with head gaskets. I haven't tried old cap but I think I still have it. I put new cap and rotor on this old one I picked up. Another friend told me that it's possible the new distributor is indexed wrong (or different) and I would have to take the oil pan off to re-index the drive for distributor. I just keep thinking that can't be right and I don't want to take the oil pan off either! Plus when I was checking timing, #1 lined up perfectly with TDC (accounting for timing advance) on compression. It will drive me crazy until I figure this out. Something is different between the old and new distributor and I can't see any difference what so ever but I don't believe in Santa Claus. I'm almost as flustered that it fired right up with a 150K distributor as I was when the new ones wouldn't work!

I know it really dont matter but if you figure it out let us know. Have a good one, gotta go turn a few, just help a buddy now sorta part time. Used to run my own shop but just got burnt out doing it every day and then at home too for family and friends, i am sure you know all about that! Been doing this a loooong time myself. Oh, the indexing thing is a good possibiliy also, only thing that makes any sense. Which leads me to think the new unit may not have been new, cant say.