I have hard time with a 750 QFuel slayer (vac. sec) on freshly rebuilt mild BB.
Engine has a mild cam 218/218 cam and good manifold vacuum (15in/hg) and runs great with a 600 EDE carb

It runs terrible rich and shakes (plugs black) ...cant drive it out of the garage. I dissemble the carb two times to find debris or cracks but everythink sems okay.

All jets are like it came from factory , power valve is stock 6,5
Float level is in the middle of the glases,

Hope anybody can HELP

 

I set the float to the bottom of the site glass. Have you made sure there is no fuel dripping down the throat? Idle a/f mixture screws set correctly?

 

Did you crack open the rear throttle blades approx as much as the fronts? There’s a screw underneath for that.

 

I have the same carb and I'm chasing a similar problem with a bad shake at idle. Seems to run great at higher rpms. I have not yet cracked open the secondaries as Mark has suggested, but I plan to try that this weekend. If you solve your issue, please post your final resolution.

 

I will try to set it to the the bottom of the glass....

​​ Do you mean i have to check if fuel dripping down the throat with engine off ?

a/f mixture screws 1 1/2 out

 

Is there fuel dripping with it off, idle, and about 1500 rpm.

Set the A/F mixture with a vacuum gauge for the highest vacuum you can get with the same amount of turns both sides.. Make sure the needle is steady.