I have a 69 camaro with a 230 inline that I just put a new Rochester 1 bbl carb on. It's idling at roughly 1,800 - 2,000 rpm, and I'm obviously trying to get it back down at or under 1,000. I reused the factory return spring, accelerator linkage connections, fuel line connection, and wired the electric choke to one of the wires for the wiper motor. Vacuum gauge readings aren't really suggesting any significant vacuum leaks, but I haven't ruled out the possibility. I'm thinking accelerator pump or choke issues? The choke does open rather fast, and it still manages to open even when I have the power disconnected. Thoughts?
Getting everything set up just right can take some time but it sounds like you are making progress.
Your idle sounds a bit high at 1100 rpm, usually engines of that era idle at 600-700 rpm. From your description the choke may be opening a little fast. There should be a lean/rich adjustment for that. Also check that your heat riser valve (found where the exhaust pipe hooks up to the manifold) if so equipped is operating properly. This provides quick heat to help fuel vaporization on a cold start. The heat riser is operated by a thermostatic spring but frequently will seize up due to rust. There is a special high-heat lubricant made to keep them turning free. Also check your idle mixture. On a 1969 model made at the very beginning of the emission control era it would usually be set for lean best idle. (Turn adjustment screw in until the engine starts to stumble, then back out a bit.) Another potential issue is whether the new carb is set at the correct float level and has the correct jets for your application, but hopefully you won't have to go there.
Likewise your dwell and ignition timing need to be adjusted correctly. Once again, no feedback, everything runs open loop and must be adjusted manually for best performance. Just to make things more interesting many of the adjustments affect each other.
Have you adjusted the idle and fast idle screws? Is the choke operating the fast idle cam? Is there something in the linkage hanging up and keeping the throttle cracked open?
I've tried both several times. Obviously logic told me speed screw, but it didn't change that much. Only about 2,500 down to 2,000 at best. The linkage is free and isn't binding, but I'm not sure about the fast idle cam. Would that need adjustment out of the box?
Everything is likely to need adjustment out of the box. If the fast idle cam is not working properly or the adjustment is turned all the way in it can over-ride the normal idle setting. What should happen is when the choke is open and you blip the throttle, the fast idle cam should move and release the fast idle screw so the normal idle setting takes over.
You have to remember that unlike a modern fuel injection system there is nothing to tell the carb what speed the engine is idling at or what the mixture is, the fuel system is essentially running "open loop" all the time. So it is impossible for the factory to preset all the adjustments on a new or rebuilt carb. The adjustments required for each engine will vary depending on its wear, state of tune, and local conditions.
You were definitely right. So I’ve been spending the past couple days adjusting the choke, speed screw, mixture, and it now idles at 1,100 when warm. Cold starts are still a issue. First fire up it’ll rev to 2 grand and die: second start same thing, but it’ll idle at like 500 and then die. Third start it revs to 2,000 again and if I step on the peddle a little it goes back to normal idle. I noticed that the choke will stay closed if I set it there, but then when it’s running it’ll open about 1/3 of the way to start and I’m assuming that’s what causing it to go all over the place.
It sounds like the carb is hung up on the fast idle setting (engine cold, press accelerator to floor once to set choke.) When properly set, the fast idle rpm should be about 1700 or so. After a few minutes, when you blip the throttle, it should come down to 7-800 rpm. Check the linkage on the fast idle cam to make sure it's coming off the fast idle setting when you blip the throttle. Something could be hung up. Remember, there are three adjustment screws on most carbs; Idle mixture, idle speed and fast idle. You may also want to check your ignition timing to see if it's not too far advanced.
UHHHHH, a inline 6, in a Camaro?
Yes, the inline six was the base engine in the Camaro at that time as it was in most Chevrolet models.