How Do You Find a Short?

[PKRWUD]

Originally posted by Rev
The most difficult leak to find is at the intake / lifter valley gasket interface. If an air leak is indicated and no other place can be found, then you may need to pull the intake and look there (last resort).

Rev

There is a test you can perform to tell if in fact you have an internal vacuum leak, like the one Rev mentioned.

1) Hook up a vacuum gauge to the intake manifold.
2) Fully close the carb throttle plates by backing out the idle screw all the way.
3) Plug up the PCV valve opening.
4) Disconnect and plug any vacuum hoses attached directly to the intake manifold.
5) Disconnect the wire to the positive side of the coil.
6) Crank the engine and observe the vacuum gauge. From 3" to 7" of vacuum (at a minimum of 250 cranking rpm) is normal. A defective intake manifold gasket will give, in most cases, a zero reading.

Take care,
-Chris