What is the average vacuum pressure that you guys are seeing on the (91) 4.0? I'm reading, from the manifold, 16 in. Hg, with the needle bouncing around slightly- never a full division of deflection- at idle. Is this normal on these things? The engine was rebuilt 1000 miles ago- is my reading a shade low because the rings still need to seat right?
average vacuum pressure
- Thread starter gian
- Start date
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
16" at an idle is about right depending on your altitude. Ideally it shouldn't be bouncing around, but if the engine is new, that is to be expected until the valves and rings seat.
