Inliners International Forums General Discussion Engines After run and backfire?

Set your idle speed to spec. you may experiencing "dieseling" due to a high idle setting and higher cyl temps with rebuilt engine. Some GM engines used an electric soleniod to control the idle so that when you turned off the ignition it retracted closing the throttle plate completely to prevent dieseling. After reading your other post you may have other problems which is causing you to have to run too much throttle plate opening at idle just to keep it running. You might want to clean and rebuild your carb completely. Also check for vac. leaks and pluged or misrouted hoses. It is probably something so simple you are just over looking it. Good Luck