John,
If you haven't worked with EC-5's before I have what might be helpful tips for you.
EC-5's take a lot of heat before they get hot enough for the solder to melt. If you don't already have a 100W+ soldering iron, get one. You want the connectors to heat up fast in order to puddle to solder, and ro re-heat the solder before you insert the tinned wire. I use the 140W setting of a Weller gun for these. Bear in mind a Weller only heats the tip for the first minute after pulling the trigger, so work fast or plan on re-triggering often.
Trim the wire insulation just enough to clear the top of the connector cup. If you don't trust your work trim just a fraction more to allow room to flow more solder after you've completed the wire insertion. If you perform a second flow have a means to assure the wire doesn't move when you re-melt the solder. This is where a "Helping Hand" type clamp can be useful.
Don't fill the cups much over half full.
I found things like "Helping Hands" clamps to be pretty much a PITA for holding EC-5's and the wire when initially joining things up. I found a small block of aluminum and drilled some holes in it that would hold the connectors vertically while I worked with them. Drilled holes for other connector types while I was at it. That little block of aluminum has proven to be nearly priceless in value. Wood works well too. I leave the brass connectors in the jig for the entire soldering process, holding the iron on the connector and inserting the wire from above. This is where the fast heat comes in pretty handy, melting the solder in the cup quickly instead of having to wait a long time for it to flow. I've done quite a few of them and I haven't found an easier way yet. There may be one but it has eluded me so far.
Once soldered those connectors can be a bear to snap into the plastic housing. It doesn't always work but I place the housings in a small pot of boiling water for about 10 minutes to soften them up a little, removing them from the water just before inserting the connectors. You'll still have to push the wire ends into the housing with a lot of force. I try not to hold both pieces in both hands but stand the housing up on a table and work the wired end from above. There will still be times you'll need to finish pushing the connector into place with a small slotted screwdriver or similar.
Where are you in the Central valley? I have a place in Valley Springs.
