The fog test was an excellent final test for vacuum leaks on the intake manifold. All openings were sealed up with tape first, then 2 or 3 psi of compressed air was used to pre-check for gross leaks, which worked very well !! I used a stethoscope to listen closely for hissing produced by leaks. A piece of tubing held to the ear would also work. Now I’ll have high confidence that the intake is leak free once it’s bolted to the cylinder head.
Blog: http://rotordesign.com/jeep/
Here is the rest of the Knock Repair Series: https://www.youtube.com/watch?v=X7uHI24cXfc&list=PLCyDzy-NaUwIhZmxHzIv0SJRHACQRIjSx