I have been tuning my Z for awhile now to rid it of a part throttle miss/stumble.I have replaced every piece of the ignition excpet for my MSD 6AL(wires,plugs,caps,rotors).I started to play with accellerator pump cams,squirters,etc for the hell of it.Still there and had a nice stumble/miss at cruise rpm,not surging..felt just like a miss.Finally broke down and went richer on primary jetting by two numbers and beleive it or not the miss/stumle is gone.Question is..Can lean primary jetting cause what can be confused for a miss or stumble?It really felt like an ignition miss at cruise but when I mashed it it would go like hell.It also seemed to get worse as the car heated up from cruising.A very small amount of throttle and it was fine,a little more and viola my miss/stumle was there,but yet mash it and you were moving with no stumble at WOT.Just curious to know if others have been thru this.Any help,thoughts or ideas more than welcome...thanks guys in advance.

 

A miss or surge at cruise is caused by a lean mixture.
Usually holley carbs are calibrated plenty on the rich side
so unless you had primary jetting much smaller than stock I'd suspect a vacuum leak. What jetting did you have in it when it was missing, and what jetting did you step up to and what
carb are we talking about?

 

Speed Demon 750DP.It came factory with 76/83 jetting and I jetted it down to 70/77 to stop it from fouling plugs when I put the motor in.That is where it was missing/stumbling at.I went up to 72 on the primary side this morning and it seemed to help this situation.Demons come with air bleeds that you can tap into the carb to fix this?Would this help cure this?