Radiator and fan clearance stock 66 Dart GT with 225

On my '64, the fan does need a spacer (at least 1 inch if I remember correctly) or it hits the balancer. I had some fitment issues when I installed my Champion radiator also.

I did a thread about it if you want to take a look, though I'm sure there are some differences between my '64 and your '66.

Also, like RRR said, slide the rad in last. It's impossible for me to install my fan with the radiator in.