I have install the correct 3/16" bead cowl/gas tank welting on two cars I restored (a 28 and 29) with minimal problems. I didn't need to attach anything to the flat part of the welting, as it was long enough to grab it on the inside. I bought my welting from Roy Nacewicz that has the correct paper core and is printable. He calls it pyroxilyn. I loosen the cowl to A pillar bolts (remove most of them) and put the welding in one side. I then mark the holes and then punch out the holes a little bigger than the 1/4" bolts and remove the welting. I then install the gas tank and slid the welting in the cowl area and across the gas tank and down the other cowl. Again I mark the holes and remove the welting cross the gas tank and down the cowl/A pillar. I then punch the holes slightly larger than the bolt holes 5/16" to 3/8". Now the holes are all made. I then slide the welting into the joint of the loose cowl and gas tank. Sometimes you need a screw driver to pry open the joint to get the welting to slid in (from the inside). Once the welting is mostly in, I use a vice grip or pliers to pull the welting bead tight against the joint. Maybe the Roy N. welting has a longer tail on it, but I have had no problem clamping onto it and pulling it tight from the inside. Roy's welting is more expensive than the cheap plastic cored stuff, but in my opinion is well worth it. The cowl gas tank welting is suppose to be painted body color. I have see some model A with black welting a to me it looks wrong. On the last welting I installed, I found a trick that worked well. On the bolt holes that are very hard to get to, like the top of the A pillar/gas tank, I used a soldering iron to burn the hole in the welting.
Rusty
