Hey sorry for the terse reply, I was at work and they don't like me getting on the internet, bunch of *****..
but funny thing is your question...I was playing around with my carb (the one that gave me problems in the first place) and I noticed that there is a "sticking point" where the secondaries won't advance any further without some force. I played with a spring, checked my throttle cable and *yes* there does seem to be some excessive slack, so I will examine all the linkage, put the cab back on, and fiddle around some more sat. night, then post back.
Having extra engines around can't hurt though, right?
For $150 I think I might buy it; seller needs to move it out of the garage. The engine is local, all thats missing is the flywheel (guy said it was brand spanking new so he kept it), oil cooler line, and a couple broken/cut hoses. Has 150k, typical oil cooler leak, but I took out the plugs and examined the seals with a flashlight and they all look solid.

 

This sounds to me like the little "t-nut" (for lack of a better word) on the top of the throttle return spring on the back of the carb (firewall side) has been screwed around with. It's possible to "flip it around" (again lack of a better word lol) if someone who doesn't understand how it works has been playing with it. The result will be that it will stop your secondaries from opening all the way, *and* it will restrict the throttle from opening all the way.

It would feel like your gas pedal stopped short - like it didn't go all the way to the floor, it just hit a wall.

You'd also feel *exactly* what you just described, like the throttle stuck a bit and then travelled further, with more resistance. It's hard to explain and I don't remember all that well lol, but once you look at the part of the carb I'm talking about, and you see how it moves, you'll understand why it feels like that. I remember looking at it and it dawning on me why that was happening.

It's hard for me to explain this - I know what it looks like and how to fix it, but I'm not too good at explaining in words. It's a pretty easy fix though - you'll be able to do it in a minute if that is in fact the problem. I wish I could actually look at your carb and show you; it's so easy to fix once you know what it's supposed to look like.

I know about this, because I've had that problem before - it didn't cause bogging in my case, but it caused throttle travel to be reduced to less than WOT.

Anyways, just an idea, I think you should check this out.

 

I did everything I know to do today and it didn't help. I checked to make absolutely sure that the secondaries start opening at about 2/3rds throttle, and they are all straight up and down at WOT (this is mechanical). Put the carb back on and the exact same problem. And there is a sound like a huge vacuum leak. The motor shakes like crazy when the secondaries open, but its almost undrivable. what to do now I guess I will try and limp over to a mechanic and pay out the ***