Hey I just rebuilt my 750cfm qft slayer carburetor and reinstalled it on my 1967 mustang with a 302 out of an 89 fox body that has had some work done to it. I know this carb is too big for it but I had it on there running fine before until it needed a rebuild.
i just got the floats set and my idle mixture screws are currently 1.5 turns out from fully seated. My idle speed screw is set all the way out so that there is a square made by the throttle plate and the transfer slots, the spring by my accelerator pump can that is behind the throttle arm and located on the post that my primary throttle plates sit on does not allow my primaries to close any further than the square that is showing for the transfer slots. This makes it impossible to lower idle speed via the idle speed screw. My secondaries are currently closed and I intend to set idle speed via secondary plate adjustments. The carb also has 75 primary jet and 82 secondary jet with a 65 power valve and factory air bleeds (70 31 31 70 for primary 39 31 31 39 for secondary) also my accelerator pump is set to squirt immediately upon throttle press.
at first it was hard for me to get the car to idle but now it is idling at around 900-1000 with the settings above and is relatively smooth, my vacuum gauge is reading around 20. I am now experiencing a weird issue where I press the gas and it seems a little sluggish which is to be expected with the 750 on the 302 however more sluggish then it ever was, also idling higher then it was, and the weird issue is that the rpm lingers high when quickly tap the gas and rev it. I have attached a video IMG_5100.MOV
any carb tuning tips would be much appreciated it, I am trying to get it back to around where it was.
this silver spring is preventing my throttle arm from closing the primaries all the way and make my idle speed screw obsolete in backing out any further. That causes the amount of transfer slot pictured under it to show.
image below is how my transfer slots are set, this is with my idle speed screw all the way backed out