I am getting ready to replace my old alternator with a newer model. It calls for 8 ga wiring and I have been trying to solder the connectors on the end of the wire, with no luck. How big of a soldering gun is required to make this work?
Thanks,

One of the "standard" big Weller pistol grip dual-wattage guns should do it. Just be sure to have the terminal & wire clean, so the heat isn't wasted on dirty conductors.

Used to solder 10ga. wire/terminals all the time with one.

A tip: Slide a length of heat-shrink tubing waaay down on the wire (about 1" long), strip the wire a bit too long for the connector, leaving some bare copper between the finished terminal and the wire insulation. Clip an alligator clip or hemostat on this void (heat sink). Solder the connection and let cool. Remove the clips and slide the heat-shrink back up the wire, and shrink to cover the terminal and joint.

The alligator clip/hemostat will prevent the wire insulation from melting due to the heat needed to do a large gage solder joint.

Just remember good soldering practice - if the pieces are hot enough, the solder should instantly liquify and flow when you touch it to the pieces being joined. Push enough solder into the joint, remove the heat, and DON'T MOVE! Let the joint cool without wiggling it.

A little non acid soldering flux helps too. Solves your cleaning issues immediately.

I have a Weller 100/150 watt gun that I have had for centurys now. Well ok...maybe not that long. I got it in the early 70's. Still works like new..

The only thing I have to do is occasionally loosen and retighten the electrode nuts so that the electrode is connected properly otherwise it doesn't reach rated heat and can be very frustrating to attempt to solder with.

I had a 100watt and it just did not seem to get hot enough. The gun would heat the solder no problem, but it just did not get the 8ga wire hot enough for the solder to flow in. I guess I will look for another soldering gun and try again.
Thanks,

As Bill mentioned, it might flow better if you use a liquid or paste flux on the wire.

Dosnt most solder come with flux in it?

Dosnt most solder come with flux in it?

True most rolls of solder are cored with a mild rosen flux. However, the flux helps clean the materials (wire) and pre-fluxing wire helps the wire to better accept the solder.

Thanks for all the input, I guess I am off to find a new soldering gun.

You might do better with one of those mini-torches. Be careful not to get it too hot.

I use a Weller Pro 260/200 watt soldering gun model. Works well even on 8g.

Looks like I am in the market for a Weller Pro 260/200 .
Thanks everyone for your help.