Idling too fast
Hi. I have a 305 with higher compression (smaller than normal cc) heads, a mild RV cam, flattop pistons, headers, and a Performer carb and intake.
I had a flooding problem with a few Holley carbs(Which I had posted about in a previous thread), so I dropped a brand new 1406 Edelbrock Performer carb on it.
It started right up! Problem is, now it won't slow down.
The engine idles at 3,000 RPM, and it doesn't matter if the engine is warmed up or not. I've even held the choke plate open with a screwdriver, and no change. So, the electric choke should not be affecting it any, right?
The (lean/rich air/fuel mixture) screws don't have any effect. The idle speed screw on the linkage doesn't have any effect. The hi-speed screw under the linkage doesn't have any effect.
We've checked, and can't find any air/vacuum leaks. New hoses, etc.. What all could cause this? Just fuel or air, right?
Could the intake manifold be leaking INTERNALLY to the engine, and sucking in air that way? Could the brake booster be leaking vacuum and cause this? I've sprayed WD-40 around the engine, carb, intake, etc, while it was running, to try and find a vacuum leak: nothing.
3,000 RPM is WAYYYY too high for a simple air leak, isn't it? This is a non-computer engine, with vacuum advance HEI distributor, so it isn't a computer or sensor issue.