223 I-6 carb problem

[Daves55Courier]

223 I-block 6 now with its third holley 1904 carburator. All three carburators did the same thing. Starts on a dime and runs great until engine warms up, then begins to sputter at idle. Messing around with the idle speed and idle fuel mixture adjusting screws on the first carburator, I noticed that just by TOUCHING the idle fuel mixture screw with my finger corrects the idle problem temporarily. Eventually it returns to running rough again and the engine will die if I dont jump out and touch that screw.
1st carb was a rebuild from Carburator exchange. 2nd one came rebuilt from a Rebcam auto parts store. I sent it back to them and they sent back a different carb. Could it be that in all three of these carbs, the new idle fuel needle screw is bad ? Or is something forcing too much fuel down the idle fuel passage causing it to run too rich ? I dont have a way to measure the gas pressure from the fuel pump, so I replaced the fuel pump which was a NEW one with another new one. No change.

 

[Anonymous]

check your float level. it might be a little off for your motor. aren't those idle screws sealed with an o-ring?

 

[Daves55Courier]

check your float level. it might be a little off for your motor. aren't those idle screws sealed with an o-ring?

Its hard to believe that 3 freshly rebuilt carbs from different places all have the float maladjusted the same way, and if the float was set too high, wouldnt gas be pouring out of the vent hole in the top of the float chamber more easily than being forced down that little idle fuel passage?

None of the 1 bbls for these 223's regardless of the manufacturer have an o-ring on the idle-fuel misture screw. They have a spring tension pushing against the valve body instead. I dont feel the idle-mixture screw is at fault on 3 rebuilt carbs.
Does anyone know if heat is the problem? Anyone ever seen a thick spacer between the carb and manifold on one of these 223's. I have never seen a spacer on the 6 or the 55/56 y-block intake manifolds. Does anyone make spacers for those ?

 

[Anonymous]

the stock spacer for the '55 is actually 6 gaskets that are stapled together.
You have to buy six seperate gaskets per carb and stack them.

 

[Anonymous]

Do you have the stock fuel pump? Those carbs cant handle much pressure. Maybe put a fuel pressure guage to see whats going on.

 

[Daves55Courier]

Several people suggested adding a spacer between the manifold and carb. I found six carb gaskets in my garage and stacked them. I had to remove the carb mounting studs and replace them with longer ones and also had to lengthen the accellerator connecting link to the new height. I drove it around today in 70 degree weather and it seems fine now.