how to install headers?

First, if you've been following other recent threads, you would realize that the Melvins rule, and that you are wasting your time since your motor is a 318. But if you are like most of us real Mopar guys, you've gotten past that and understand that your 318 will respond well to a few simple, and not so simple mods. The headers will be tough.

The 340 833 Dart reply has good instructions, but he forgot to mention beer...and you may add raising the car for extra clearance to install header from underneath.

When I put hooker comps in my 69 318 barracuda notchback, I used a cherry picker to pick up the front of the car about 3' off the ground, and lifted the motor a few inches higher (via come-along tied to garage roof truss). This provided plenty of extra clearance and made the whole installation easier.