Low vacuum, poor gas mileage

[ClydesdaleKevin]

I'm pulling a crappy vacuum...My gas mileage is in the toilet at about 5.8 mpg.

If I hit the trottle too slowly she wants to bog down...there is a flat spot I didn't really notice before just before the secondaries open up...I'm thinking its something to do with the choke since I reused the old one off the old carb because the new one was different enough to where I'd have to modify the hot air intake on the manifold to use it.

Right now, if I set the choke to where it stays closed enough to start the motor easily when cold, it doesn't open all the way, and then the rig runs like crap and stalls.  If I set the choke too open, It won't start at all.  If I set it to where its closed but opens up a little when the motor starts, it will start but stall right away...unless I hold the butterfly closed a little with my index finger until it warms up just enough to stay running on its own...and then it runs fine...although I still get that flat spot accelerating...and its bad enough that I have to downshift to first when I'm stopped so that it revs up to speed...otherwise it acts like it wants to stall out.  Then I shift to second, then drive, and all is well at highway speeds.  Any ideas?

Kev

[ClydesdaleKevin]

I'm beginning to think my original idea, that the choke is the culprit, is correct.  I'm definately running way too rich, and since you can't adjust the mixture on a quadrajet carb, it has to be the choke setting.  On the body of the choke itself is are the words "leaner" and "richer" with arrows in the appropriate directions...so if you adjust the choke, you are leaning it out or riching it up.  And I'm really thinking that the choke that came with the new carburator has a different "throw", distance the arm travels to open the butterfly, and a different rate of opening than the old choke from the old carb.  We'll see in AZ when I have time to install the new choke and modify the heat riser coming from my manifold to work with the new choke.

Another bizzare thing is that when we were finally through San Antonio and the weather warmed up. the rig started running better.  Prior to that the air temp outside was in the 30s.  It was also a higher elevation...and I had no problem with even the steepest hills going 55mph.

And the flat spot wasn't nearly as bad.

Gas mileage went back up to around 6.6.

Now its cold again and I can smell the excess gas being dumped into the carb.

Curiouser and curiouser!

Kev