'48 8N idles rough when warm

starts well, idles smooth when first started, progressively runs rough as it warms up , so far have changed, coil, resistor, cap, plugs, wires, rings, valve train, carb rebuild and same results, when under any type of load it smooths out, checked the intake manifold for leaks to atmosphere and to exhaust have shorted out the resistor and ign switch, no change, pulling the choke a little smooths it out and speeds it up, what am I not getting right?

(quoted from post at 15:18:06 08/27/16) starts well, idles smooth when first started, progressively runs rough as it warms up , so far have changed, coil, resistor, cap, plugs, wires, rings, valve train, carb rebuild and same results, when under any type of load it smooths out, checked the intake manifold for leaks to atmosphere and to exhaust have shorted out the resistor and ign switch, no change, pulling the choke a little smooths it out and speeds it up, what am I not getting right?

Click to expand...

b:06cd7ed849][i:06cd7ed849]

Sounds like ya may need to reset the air to fuel mix.

Try this....:



Gary[/i:06cd7ed849][/b:06cd7ed849]

(quoted from post at 20:10:17 08/27/16)

(quoted from post at 15:18:06 08/27/16) starts well, idles smooth when first started, progressively runs rough as it warms up , so far have changed, coil, resistor, cap, plugs, wires, rings, valve train, carb rebuild and same results, when under any type of load it smooths out, checked the intake manifold for leaks to atmosphere and to exhaust have shorted out the resistor and ign switch, no change, pulling the choke a little smooths it out and speeds it up, what am I not getting right?

Click to expand...

b:c52338f950][i:c52338f950]

Sounds like ya may need to reset the air to fuel mix.

Try this....:



Gary[/i:c52338f950][/b:c52338f950]

Click to expand...

Hopefully that does it, very likely could.
If not I would think the carb still has a passage plugged.
It's easy to miss those idle circuit passages.

well i have done the carb jet settings numerous times and cleaned out the passages a few
times , would there be any chance that the jet orfice for the economizer circuit could be
too big, . I have drilled and tapped the intake manifold and use a vacuum gauge, it reads
17.5" most of the time but when it stumbles it fluctuates downward about 2" when it is
first started it runs fine until it warms up, . I can drive it in 2nd or 3rd gear at just
above idle on a flat surface and it stumbles but as soon as a slight incline is tackled it
smooths out when gov opens up a little? Still need lots of advice thanks