1) Does it smooth out once the rpm stabilizes a bit? Just stumbles on acceleration? Or does it fuss at any RPM above idle?
2) You say timing is set correctly….you mean initial timing, I assume? Have you checked to see that the vac advance is working? Does the distributor rotate and return quickly and smoothly when the throttle is goosed? Might be worth checking “total timing” at RPM with a light, if you have not done so already.
(***** the fact that this same carb ran fine for two years with that same jet (even if it’s the wrong jet) makes me highly skeptical that jetting is your problem. It still might be a fuel issue of some kind, but I’d suspect the jetting is not creating your current symptom.)
3) Will the truck stay running (even poorly) if you hold it at the RPM where it starts fussing? If so, use the hand throttle or a partner to help hold it at that RPM. Fill some sort of container that will allow you to squeeze some fuel down the throat one a fairly controlled way (a ketchup bottle works well). While the truck is running at its “bad spot” RPM, squirt some fuel down the carb and observe the change.
Does it get better? You can safely assume it needs more fuel and keep exploring that avenue. Don’t forget fuel pump or obstructed filter/line in that equation.
Does it get worse or little change? Some circuit on the carb is dumping too much fuel (common B issues) or you still might have not the right spark at not the right time.
Last edited by JW51; 05/17/2024 12:45 PM.
