Forgot to send the photos, note the wet secondary During Idle!

and this just in, when the car is off, fuel is dripping from the Vac. Diaphram Shaft where is screws to the secondary plates....does this mean the shafts are leaking????

I gave up on a Holley and bought a Summit 500cfm carb. Best $300 I have spent on my Mustang.

When you rebuilt it did you put the check ball back in?

M1Mustang69 wrote:

Secondary float level was set correctly on install (as per Holley Instructions). I tried turning it in. No change

I have a second 1850 that I'm going to try swapping the throttle plate to see if the leaks stop, but this idle/secondary booster thing is baffling

But have you checked it with the engine running? Also if I remember correctly isn't there a little pin with a pointed end that goes under the squirter? Or is that just for a double pumper? Man, been a long time
 

-Triton - The Diaphragm secondary does not have Check-Ball, it has a little brass insert with a small hole pressed in where a check-ball typically goes!

-Raymond - The I did drop each Float while the vehicle was running annnnd I did put the Check-Pin back in the primary Squirter!  

The Fuel Drips very consistently and steadily from the secondary Boosters-------------and I have NO CLUE WHY!?!?!?!  very frustrating.....Not to mention the new fuel leak slowly dripping from the Diaphragm Rod Screw area!?????(only when car is off)
 

Well - Not sure of your experience level, so I apologize if this is basic for you: The dripping secondary boosters, and the idle screws being turned all the way in (lean) would be consistent since the engine is getting all the fuel it wants at idle due to the dripping secondaries. First thing that I would think of - the inlet needle valve on the secondary side isn't sealing completely.  Did you replace the inlet needle valve assemblies? . Try removing the sight plug on the secondary bowl while the engine is running - does fuel constantly drain out of the hole? That indicates that the secondary bowl is overfilling. That is commonly caused by dirt stuck in the needle and seat - it doesn't take much. I think I'd remove the secondary needle and seat assembly and either replace it if you haven't already, or blow it out with some compressed air. Then reinstall and reset the float level while the engine is running. Fuel level in the bowl should be just at the bottom of the sight plug opening. If it still overfills, then the float may have a leak and is sinking, allowing the bowl to overfill. In that case I'd replace the secondary float.

Thank you kevin….no offence taken for obvious reasons....moving forward, to spare you im passed the basics, I rebuild these guys, but im not an engineer, or haven't been working with all sorts of carbs for decades like most....so when some funky stuff happens I may not know why...this was the first time I saw Constant Dripping from the secondary booster circuit, so your insight is greatly appreciated....now I know 

So the update is I concluded the throttle plates were worn and damaged (from the dripping fuel when the car was off by the vac. secondary Rod.....)  so I swapped it with a newer one....disassembled the secondary bowel and thoroughly cleaned it again with carb cleaner......the needle valve seemed to function consistently, with that observation I assume it would function better with constant lubrication from the fuel....

bolted it back on and whammo, everything was Kosher!  all booster dripping stopped, all leaks stopped....car idles fantastically!  
Conclusion: Vac leaks on throttle plates and Debris on Needle Valve.....

owner of the 68 Stock 289 2v C4 Coupe has said that he whole heartedly does not recall a time when his car has run this Strong....Owner of 38yrs....(converted intake to 4bbl and after 3 carbs laded on the Holley 600cfm)