lol. i like having both tires spinning and the back end of the ramcharger going sideways

 

I do as well.
Though the thought of the 400 having an LSD behind it is rather scary with a long bed. lol

 

you must have forgot about this

 

Quit posting that, damnit.

 

Quick thought, would a leaky carb at the top of the fuel bowl cause a vacuum leak?

I'm about to the point of messing with the idle mix screws to pick up some off idle power.

 

no. the float bowl has a vent tho. it should not cause a vacuum leak.

when adjusting the idle mixture screws you adjust the left and right mixture screws equally until you can get it to idle as high as possible. then you adjust the throttle stop screw to make the truck idle where you would like.

 

Blast.
I need to figure out where it's leaking. I'm pretty sure I've got a vacuum leak SOMEWHERE. I just can't figure out where. It still stumbles a bit with the vacuum advance disconnected, or hooked to straight manifold.
GAAHHH.

I am kind of hoping maybe I can fatten up the idle a smidge and eliminate the stumble. Am I partially correct?

 

this is were it would be nice if you had a vacuum gauge. it might help verify that you have a vacuum leak. with how few vacuum lines there should be on your truck it should easy to check. does it seem to idle fine? if so then you may not have a vacuum leak. could possibly have a bad accelerator pump. i would probably get the truck up to operating temp and then try adjusting the idle mixture screws until it idle as high as you can get it to then see if things run better.

 

It starts and idles great. It started surging maybe 200 rpm at one point a couple weeks ago, but it hasn't done it since.
When the idle is as high as it can be with the idle mixture, that would be leaning it, right?

 

no. that would should be the sweet spot where it is about perfect mixture. turning the screws clockwise from that position would make it lean and counter clockwise would make it run a bit richer.