Engine dies at idle

[OldSkool]

I installed a rebuilt 2bbl carb on OldSkool and still have an idle issue. The engine acts like its running out of fuel but WOT will go to 5500rpm with no problem. As long as I can stay t 800rpm idle it will stay running but thats to high to take gear in.
So do you think it can be the vacuum advance in the carb stuck? Timing is dead onI'm going to pull the plugs tonight to see if any are fouled out.

Any suggestions are welcome.

 

[testlab]

Sounds like the idle mixture screw setting is wrong or the idle bypass jet is blocked. At 800 the throttle plate is probably starting to open and the it's running on the main jet. I'm not sure what carby you have but I'd start looking at these things first.

Also... Did you set the base ignition timing?

 

[OldSkool]

Timing is in good shape. Is the idle bypass the small jet in the bottom of the float bowl? It's the only part I cold not gat out and I was afraid I would ruin it trying to get it out.

 

[testlab]

Which carb do you have? Some use the main jets for idle and some have a separate circuit. Make sure that ignition timing is spot on to because it can cause a lot of idle problems and unnecessarily chasing carb settings.

 

[OldSkool]

The timing is right on. There is no idle jet adjustment on this carb. It's a Rochester 2bbl. (GM). When I opened the carb up there was a lot of scaling on the bowl like water had gotten into it though the filter was in good condition. I cleaned it up and installed a carb kit. I blow ever orifice out as I went through it.

 

[testlab]

I'd like to help more but I'm not familiar with those. Good luck, hopefully it's just adjustment (I think they have two idle mixture screws??)

 

[OldSkool]

Thank test and yes there are 2. Before rebuild the screws did nothing even when screwed all the way in. Now they make a difference when screwed in. Adjusted them from bottom out 2 turns to get the engine started then fine tuned them after start. Still will only idle at 800 and dies out at 600rpm. Engine was running great then all of a sudden not so much.