Originally posted by techinspector1
Never thought much about it, don't see how you could. But it did get my mind going. What about this? I'll assume the use of a carb, although with some ingenuity, you could do the same thing on an efi motor. Remove the carb and make a flat cover plate from maybe 1/4" steel to replace the carb and block off the hole in the intake (with gaskets to make a leak-proof cover). Remove the valve covers and all spark plugs. Procure a fitting that will screw into the spark plug hole in the heads and allow a rubber hose to be fitted over the nipple end of the fitting. Roll the motor over by hand until any cylinder you want to start at has the intake valve open to full lift (doesn't need to be exact). Now, pull another running vehicle up next to the car to be checked. Plug your vacuum gauge into a manifold connection on the running car to record the vacuum at idle. Now run a line from the manifold of the running car to the manifold of the car to be checked. Connect your vacuum gauge to the manifold to be checked. Record the reading. If the motor being checked is pulling the same vacuum as the running vehicle, I'd say the checked engine is sealed up pretty well on that set of runners. On a 180 degree manifold, you'll be seeing vacuum on 4 of the runners at the same time. You can tell by looking at the runner layout. If you see reduced vacuum, use a stethoscope to listen for the hissing sound of air moving from outside of the manifold or from the valley of the motor into the manifold runner from inside the motor. Now move your nipple to one of the cylinders on the other quadrant of manifold runners and repeat the procedure. The further away your running vehicle is, the easier it will be to hear air moving around in the checked motor.

Does this make any sense to anybody out there?????...or am I way off in left field?????

you're way way off in left field. some people make a living finding vac leaks. there are better ways than that, but ill watch him do what you just suggested and see how it works. go for it aftershock2222 .