make sure the cable is not hanging up on the cable guide under the bottom bracket

I'll try routing the cable UNDER the pinch bolt body. I'll see what happens.

But there is no hex tension adjusting bolt on this FD

there does not appear to be "Stops" on the barned shifters themselves. They just butt up against the top and bottom of the mount body. But I too am surprised at how little range there seems to be on those shifters.

Updates.

1. I backed off the small ring limit screw a bit to allow the cages to sit more centered over the small ring (so to have a little more clearance than absolutely necessary but also to allow enough travel inside to move the chain down)
2. I adjusted the orientation of the FD very slightly to better align the cages parallel to the rings.
those two moves improved things to a large degree.
it would then shift across the three rings quite well. A bit of hesitation but eventually it shifted.

the only issue then was that in the Big Ring, when in the 3rd, 2nd and 1st smallest cogs, the chain rubbed the outside cage. but I could live with that.

3. I finally tried rerouting the cabel UNDER the pinch bolt body (so back IN to the center of the frame.. See photo.) this was a bit tricky because when you tighten up the pinch bolt it wants to loosen the cable wrap. I had to hold the cable VERY snug.
But ultimately this improved the shifting too.

so I am pretty much good to go on the front end I think.

Many thanks for all the insights and suggestions. Very helpful.

Peter

Not sure which FDs had the adjuster for spring tension. Some of the models in the FD-M73x era had these, at least on the later versions. Also seen it in the LX FDs of the same era as well as the FD-6401.

Overall glad to see that the changes that you made have helped. Guess that with older chainrings that doesn't have the modern tech, front shifting becomes a 'brute force' task.

Enjoy that overly large frame. Don't see double top tubes too often.

I haven't read the thread thoroughly so please excuse any redundancy.

I've used those exact shifters with two or three triple cranks, road and mtb.

I've used road front derailleurs send they've shifted the triples perfectly. The left shifter has no indexing so all that's needed is to get the height, angle and limits set. Very simple. I believe the shifters must use road FDs.

A fellow on the RBW Rivendell Group shed some light on WHY routing the cable UNDER the pinch bolt helped my shifting.
he wrote: "That's an M735 front der. I think you may have better luck with an M737. The M735 has a really long lever arm, which requires a lot of cable to pull it. The M735 was pretty much only used with thumb shifters, which had a comparatively large barrel, and thus pulled a bunch of cable. The M737 has a shorter lever arm, and does not require as much cable pull to move it around. Those were intended to work with rapidfire shifters, but worked well with barcons. "

and that reasoning makes a lot of sense. since i have limited cable available in these bar cons, lowering the attachment point (by routing Under the pinch bolt) would shorten the arm above the pivot and so require less cable to move the FD body the same distances. (I think)