I can say with certainty that, functionally, it needs to be connected to one of the intake manifold plenums downstream of the throttle plate. Can you give a little background of why you are asking this question? Has/had it been disconnected (that would be bad)? Hopefully, a 412 Owner can post a picture (and answer with certainty), but this 412 SPC figure: Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc. shows two likely vacuum source fittings IMO on the intake plenum -- items 34 and 40, Then this 412 SPC figure: Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc. implies that "Ts" -- items 52 and 37 are connected by short hose pieces to the aforementioned fittings 34 and/or 40. The smaller nipples on items 52 and/or 37 look like a good suspect as a place where the small vacuum line going to the MicroPlex ignition ECU would be attached. Good hunting! (but hopefully, a 412 Owner can give you a more certain answer.)
Hi Steve Thanks for taking the time to put togehter such as detailed and considered reply. The reason for asking the question is that I can't see where the hose dissapears under the dash, its somewhere in the A plillar ( its a RHD 412 GT btw). and it doesn't seem to emerege anywhere. I presume its purpose is to sense vacuum and modify the advance curve ? I only noticed it was there while poking around under the dash, replacing the throttle cable. I'm reasonably familiar with the top of the engine ( had the heads off) and there are no spare or unused vacum ports visible to me anywhere, nor is there a hose dangling in the wind, looking for a vacuum port to plug. Mystery ! I don't think 34 & 40 are potential connection points as the parts diagrams show no tees and they are already connected elsewhere ( and the same on both sides) and the hoses connected there look "right". 52 looks more likely, however the parts diagram shows its for an automatic car, and mine is manual. M
Exactly. Unfortunately, on the non-US version cars, there are fewer technical diagrams and figures for both the injection and ignition systems in the OMs.
I borrowed a borescope and managed to follow where the vacuum tube goes. It connects to a port on the rear of the left hand cylinder head inlet plenum, beside the brake vacuum port. The connection spigot is not shown in the parts diagram, but it's adjacent to 45 in the following diagram. Mystery solved. Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc. M
