I've got a big bore TQ on my 340 and at a slow steady cruise speed (some at highway speeds but not as bad) I get some slight surging and it seems every so often it sounds like it will die. It feels fuel related. Anyone?

GIVE the tree a turn or so CLOCKWISE .... it will raise the rods and give it another jet-size or two.

Yes, I agree, try richening the primary metering rod tree.

Doing it now, then for a ride.

Went around town (small town) and it seems to be worse with 2 turns CW.

do you know what rods are in there ?

I have no idea.

You might want to pull them out and check the "steps" in them ...

What would I be looking for, a baseline?

CW raised the tree right? Might go a bunch more turns & if that helps, it confirm (or deny) that it's a lean prob which it sure sounds like classic lean

Was it surging before the engine work? If it ran OK I would go back to where it was then maybe go 1/8th turn at a time and run it up the Golden road. Does the secondary air valve snap back into position if you tap the rear?

It was doing it before the engine work, and the last time I took it up the Golden Road I broke a frame rail on the speed bump before Abol bridge, forgot it was there and had 5 people in the car. I'll do some more tuning tomorrow. I'll let you know what I find.

Are you able to pull the rods out? .. there should be THREE STEPS in the rods ...at least most of them do. If you have the TWO STEP ones ..... that could be why you don't see any diff.

I have adjusted the tree every which way and no change, could the floats be high?

i would open it up and check the floats, then set the height correctly