I have qjet, off the car that I'm rebuilding. When I turn the mechanical throttle linkage by hand, the primaries open wide, to perpendicular. The secondaries open pretty wide, but not the whole way, say to 70-80 degrees instead of 90. Is that right? Does vacuum handle the rest? If it isn't right, how do I adjust it? TT
they should open 90degrees ideally. there is a tang on the primary throttle shaft that rotates with the shaft. As the throttle opens, the tang rotates rearward and contacts another tang which in turn pushes on the secondary link which opens the secondaries. bending the second tang a little towards the front of the carb will get you additional degrees of secondary opening. Also pay attention to the secondary link - is it bent? is it adjusted right? there are three or four pieces there that operate the secondaries. changing one can have an effect on the other.
The rod is straight, that's for sure. Those tangs will bend will they? Hmm, hope I don't snap anything.
I typically make that second tang adjustment using a needlenose pliers fwiw If I need to change the first tang I tend to use a long screwdriver and ball peen hammer
This is a long shot but... Once when I was rebuilding my Qjet I had the same problem. It drove me nuts until I saw that the accelerator pump rod was too tall in the rebuild kit (by about a 1/4" if memory serves). I cut it "down to size" and everything went perfectly. Like I say, a long shot, but maybe...
I've built at least 4000 in the last 10 years since we went full time here, and never in one single instance did they not require some minor "tweaking" to get both sets of throttle plates to a full 90 degrees when fully open. My book describes how to make a positive stop for them, which is highly recommended if you want the carb to come to a full open position every time you go to full throttle. Many early units that don't use the double spring arrangement already have the provision for a positive stop, all the double spring varieties or going to need one.......Cliff
Working as intended. I did some research on this some time back, and they're only supposed to open to 80* on big blocks and to 70* on small blocks. You can tweak it as mentioned earlier to get more out of it, but this is normal operation from factory.
