I have a question maybe someone can answer. I Have a 1977 Dodge 318 engine, which is from a military Dodge M886 Ambulance I'm restoring. When I tried running the engine, it usually needed a little help from some starting fluid to start. It would only run poorly,(miss and sputter) at a mid range RPM or above. It acted like it had little or no engine vacuum. I rebuilt it's carb, but that did not help.
When I checked things out, I noticed, down inside the intake manifold, directly under the carburetor, a very clean,open tapped hole-- like something was removed. I have never seen anything like this in an intake before. The hole seems to connect the intake's planes, or something. When I checked out the truck's parts manual, it showed a part called "Plug, manifold vacuum control" which installs in the hole. So--
Does anyone have any insight or knowledge of this? Does the engine require this plug to run, or did it come from Dodge like this(open hole)? One guy told me, that the open hole connects the intake passages to the exhaust crossover, and the plug allows a tiny amout of exhaust to mix in to the intake stream-like a primitive EGR.
Bear in mind too, the truck was built for the US Gov't, and was exempted from emission controls in effect at the time-1976 and 1977.
So--anyone know what's going on here? Should the hole be open, or plugged?
Thanks!