Chevy,

Long winded answer coming:

I've fitted electric fans to my Amazon and to a TR6 that we rally. Fit the fan to which ever side of the radiator you can (back is better, because the fan doesn't obstruct the fins, but it's no big deal).

Then fit a decent relay (at least 25A), drawing fused power through the 30 and 87 terminals, to the fan, then to earth. You must use a relay, because a switch will melt down if you try and switch that much current through it. Use heavy cable (capable of at least 25A) for the same reason.

To triggger the relay, pick up live (also fused, but since it is only switching the relay, it need not be high amps) power and run to one side (i.e. the 85 or 86 terminal) of the relay. The other side (i.e. the 86 or 85) side of the relay goes to a 3 way (i.e. on-off-on) switch on the dash. One side of the switch goes directly to earth, the other down to a thermo switch, then to earth. This is a bit of overkill, but it lets you turn the fan on or off yourself, or let the thermo switch take over (which is what you do all the time anyway!)

I had a fitting sweated in the bottom tank of the radiator to take a screw-in thermo switch, although it is probably easier to get one of those thing you poke between the radiator fins, or slip in a rad hose. Your local AutoOne in Chatswood sells them. I don't like them much, although they are adjustable so you can change the temp at which the fan cuts in.

If you go the thermo switch route, get one that turns on when the water going back into the block is the temp you want for cooling.

You can put a thermo switch in the top tank, but I figured if your water level gets low, then the switch mighn't be immersed in water and so mightn't work - just when you want it to.

JohnH

PS Make sure the fan is wired the right way around - put the + and - back to front and the fan will run backwards: you don't want that. Make sure that air is coming through the rad from front to rear.