This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
Pete O Dickerson wrote: My 75 Dodge Swinger 318 would ping at part throttle
operation, not at full throttle (floored!) like you might expect. Just going
over an overpass or up a hill the engine would ping and clatter, even
ignition timing and carburetor were set correctly.
The manifold was made from cast metal. The molten metal was poured into a
through a little hole and when the manifold was finished, the little hole was
plugged up with a little rubber plug. Well, after a few years this little
would dry up, shrink, and fall out, leaving a hole in the manifold. This hole
would cause a lean condition to exist at part throttle operation, by
Try removing the carb and shining a flashlight down into the manifold and
if there is a hole in the bottom of the manifold. You can either plug it
replace the manifold with a more performance oriented unit.
(The maintainer adds: invest in a vacuum gauge, they are cheap!)
16: Fast idle, then stalling.
>From Timothy Economou: If you start your car and it runs for a while at fast
idle and then it starts to load up and then stalls. There is this little
thing on the open end of your breather that closes the outside air when
is at fast idle and lets it draw air from the manifold. (Stove control). Check
Editor's note: the stove control is frequently bad on vintage vehicles. The
vacuum hose, control, and mechanics of the flap in the air horn should be
checked. See above.