Hi guys, I have a stock 750cfm carb on my 76 vette, anyways, when I floor it, the vehicle basically pauses for about a second then it kicks in... The primaries are working just fine because if i keep it under the power requirement for the secondaries, there is no pause at all.... As soon as my secondaries are needed though.... that annoying pause comes into play... I think that they secondaries are either allowing too much air to come in too soon and the mixture is too lean... or the secondaries aren't opening soon enough.. hell it could even be the accelerator pump... I took it to get rebuilt about a year ago at a local shop here.... could they have set it so that it would be ideal for the l48 180 hp engine? (i have about 300hp now...) anyways these are just some ideas I came up with, so if anyone could help me out, i would appreciate it, thanx ;) :eek: :nopity :eek:

 

if it is a Q jet the secondary air valve is opening to fast. check the windup on the spring and also check the choke pull off as this also controls the air valve opening rate.

 

Yeah its the rochestor Qjet, ill be sure to try that, thanx :yesnod:

 

Stinger -
Clem is right - your secondary airvalve is set up too loose. Set the spring windup to 7/8 turn to start with. You can then unwind it 1/8 turn at a time until the car stumbles, and then tighten it up a hair. This assures that the airvalve is set up to open as quick as the engine can handle it. The following is the procedure I outline in my Q-Jet tuning paper for adjusting the airvalve:


The secondary spring windup is adjusted with a small, slotted-head screw on the passenger side of the carb, right at the top of the carb on the secondary side. The screw head points right out to the side. 90 degrees from this, on the bottom, there is an allen-head lock screw that keeps the slotted screw from turning. If you have trouble seeing it, place a mirror under the area until you spot it. With a small slotted screwdriver holding the adjustment screw, loosen the allen screw about ¼ turn. This will allow you to turn the slotted adjustment screw. Counting the turns, allow the slotted screw to slowly unwind until all spring tension is gone. You can use your mirror to see the spring disengage contact from the pin lever underneath the air horn. If the spring tension was lost after only ½ turn, the windup was too loose. Bring the spring into contact with the lever. Note when it just barely touches. From this point, wind the spring up between ¾ turn and 7/8 turn. This is a good starting point, and will prevent any bogs or hesitations due to premature secondary opening.