My resleeved original 376 carb on my 1960 99 only ticks over, albeit richly, with the air screw removed!
All is clean inside and the float level correct, its driving me nuts!
On the open road there is no oomph over 50, possibly due to the hole where the air screw should be...
You have to dismantle the…
You have to dismantle the carb. See that all passages are clear and that the sleeve is not covering the passages that go all the way through the carb body.
and also through the jet block:
If the sleeve was inserted low enough then these holes should have been drilled in the sleeve to match them up otherwise they will be blocked.
I have done all this, pass…
I have done all this, passages are clear. I tried a 389 I have and the air screw worked as it should.
The only remaining suspect part is the new? Chromed slide. It seems a little slack but can't think of any mechanism that would cause the air screw anomaly.
So, with air screw in you need at least a quarter throttle for the engine to run at at all. And without it the tickover is rich but sustainable, as I said, on the road with no air screw there is no pull over half throttle.
The air screw controls the pilot circuit, first thing I'd do is check that the circuit and jet are clear. I'd also check what pilot jet was in there and put it back to,standard if it isn't?