Well guys, we finally got the 355 in the car and it runs fairly well, especially from 3500-5500. The problem I having is when I'm stopped, it will intermittently surge. Set the idle up a bit and that stops it from cutting out, but if the ac is on it will cutout. The carb is a quadra jet that was rebuilt by a local shop that specializes in carbs. It was working great on the 305, so it leads me to think that there might be some kind of computer problem. It's a hydraulic cam 204/214 @.050, 110 lobe spread. The compression is 9.1 Do I need to have a chip burned for this to run correctly?

 

The EPROM programming has little effect at idle. A new 350 chip will give more timing advance which would add a few more top end HP, but is not needed for the engine to run.
You say you have an interment “surge” which means the RPMs speed up. Do you mean “stumble” as in RPMs slow down?
Doubt it’s a carb problem.
When do you have the problem? With a cold motor, during warm-up, or only during closed loop operation?
When tranny is in Neutral, Park, or Drive? Could be tranny or lock-up TCC problem.
Do you still have an EGR valve? Too much EGR can cause stumble.
Do you have a timing light? I wonder if the ignition is stable when you have this problem?

I’m not sure about an 85 LG4 Auto, but on my (83 Manual) car there is an electric solenoid on the front of the carb that is energized when the AC is switched On, it opens the throttle slightly so the engine speeds up to 1500 RPMs in neutral. I can watch it working be removing the air cleaner and starting the motor.

 

I guess you would call it a stumble. The rpms drop 300-400 and almost always come right back up. It happens after it's warmed up. I guess I need to check my egr functions. I haven't adjusted the throttle kicker yet. I would like to get it running just right at a normal rpm, then adjust the kicker to increase it to about where it idles now ~900-1000. Any more thoughts?

 

Any other ideas?