While it is possible for an individual to fit the top, E.R.A. recommends that the top be installed by a professional upholsterer, especially if you have a roll bar. The following general guidelines will be of some help. ERA takes no responsibility for any damage resulting from installation of the top by any party. 
PDF installation manual here If you intend to install side curtains in the future, E.R.A. can supply a template to duplicate the correct windshield angle, or you can use an angle gage to set the glass angle at the center of the windshield to 44-45 degrees above horizontal - with the chassis rails level.

Do not try to fit a cold top! Always work at room temperature or above.

To prevent scratches in the paint, tape heavy paper over the area of the rear body snap studs. Punch holes so the studs protrude through the paper. Some detail pictures of a finished top here.

Install the front channels onto the windshield frame. The inside portion of each front channel has a stud that fits into the slot of the frame. See below. Press down to engage, slide to the outside and down in the windshield frame. Check that the stud is secure in the windshield frame.

Secure the stationary brackets to the windshield side posts with the screws provided.  Use a mild threadlocker like Loctite Blue on the screw threads. 

Latch system

Assemble the rear bow halves together. Turn the knurled adjusters all the way into the ends of the bows. 

Install a ferrule in each of the receptacles adjacent to the body just outside the seat-backs. Slide the bow assembly into the sockets with the hinged brace toward the rear.

Install a snap on each rear flap as close as possible to the outside corner: 

Punch a center hole in the fabric. Use the snap backing plate as a guide to make 4 small slits in the fabric with a sharp knife.  If you don't want to cut the holes directly, press the outside piece into the paper to make a mark.  Then, accentuate the marks with a pen and cut the slots.

(4) From the outside, insert the prongs through the small slits. Install the snap backing plate to the underside of the material, bending the prongs to secure the snap. 

Lift a Dot installation

Lay the top in place over the rear bow and secure the snaps to the studs in the body closest to each rear door opening. If the top is too tight for the snaps to reach the studs even at the lowest height adjustment, remove some material in the where the main bows come together to create some slack. 

If the frame doesn't follow the contour of the fabric, it can be "tweaked" to fit by hand/over-the-knee bending. 

Starting on the passenger side of the car, install the balance of the snaps in the center of the flap, alternating from each side towards the center.

Snap installation
If you have a roll bar, slice the back panel below the window to fit around the roll bar back leg.  (The 289 FIA's brace goes forward, but the top of the roll bar hoop still requires a small pocket.)

The filler will be added later.

top with roll bar
Back leg of roll bar

Beginning at the center, carefully un-tape a portion of the top fabric from the windshield. Glue a portion of the top fabric to the front vertical face of the channel with contact cement. Do not apply the glue to the top of the front bow, only to the front surface. Work from the center to the sides until the entire top surface is glued. 

Remove both front bows and wrap the front of the fabric around inside the channel, leaving a couple of inches hanging at the sides. Trim the excess front fabric and glue the material into the inner surface. See above. 

If the car has a roll bar, carefully make a slit from the bottom edge of the top to about 1" into the plastic window. A small boot can be made from two pieces of fabric sewn together, sandwiching the top material between them.

pad under lift-a-dotGlue felt pads to the underside of all snaps to prevent paint damage..

Use 2" masking tape to tape each front channel down to the top of the windshield securely at the outer edges. Pull the top fabric over the top of the channels, beginning at the center and working over to each side, taping the material to the windshield glass as you work.

tape on top

 Alternately adjust the top over the rear bows and pull and re-tape the top material at the front to remove slack from the top and minimize wrinkling. Do not pull hard at any time. Stress can break the windshield! Make sure the top material is centered on the front bows and windshield. Keep adjusting the fabric at the rear and front of car until the top is smooth and sag free.

With the top fabric installed, tape down the edges of the front bows securely.

Attach the latch "hooks" to the windshield frame using the hardware provided. See the diagram above. Determine where the latches must be installed on the front channel to provide proper tension on the front channel when installed with foam rubber between the channel and top frame. Mark the holes for the latches on the fabric of the front channel, then remove the channels from the car to drill the holes for the rivets.

Rivet the latches to the front channel. Remove the remainder of the mandrel from the rivets, and peen the backside of the rivet as flat as possible. 

Glue the extra flap of material on the top over the exposed rivets on the backside of the front channel. 

Glue 1/8" thick foam strips to the inside of the front bow channels to seal the top of the windshield frame.

(after fitting) 

Cold temperatures make top installation difficult. 

  • Install the top bows with the hinged frame toward the rear. See above.
    (Use the threaded adjuster to lower the frame hoop for easier initial installation.)
  • Lay the top in position across the top bows. Install the header channels on the windshield by engaging the header tang into the slot in the top of the windshield. 
  • Engage the outside windshield clamps to the header, but don't cinch them down. 
  • Working toward the center from each side, press the lift-a-dot fasteners onto the body studs. It helps to rock the fastener back and forth a bit. 
  • When all lift-a-dots are secure, cinch down the windshield clamps and adjust the height of the bows at the sides. 
  • If the top is too loose, unscrew the knurled ends of the top bows to raise everything. 
  • Remove in the reverse order.