An important step in prepping the intake manifold for the 4.0 Jeep engine, is to remove all of the carbon inside the first 2 inches of the intake runner, and especially the fuel injector ports. This carbon is soft and doesn’t require fire or even oven cleaner. Just a little carb cleaner, a few paper towels, and a hack saw blade, as you will see. There is no more carbon after the first 2 inches.
Blog: http://rotordesign.com/jeep/
Here is the rest of the Knock Repair Series: https://www.youtube.com/watch?v=X7uHI24cXfc&list=PLCyDzy-NaUwIhZmxHzIv0SJRHACQRIjSx