Hey all,
So I have all the parts necessary to rebuild the original PCV system on my 390 as shown in the pic. Just hoping someone out there can help confirm all of the intake manifold vacuum fitting connections for me…that is, the ones that are not shown connected in the pic. Should be four by my count…two on the front fitting (C7AZ-9A474-A) and two on the rear (C8OZ-9A474-B). I have an idea of the final config, but am looking for verification.
Thanks…
I have a 68 GT 390 with automatic transmission, speed control and a/c and tilt wheel and I am trying to figure out some of the same vacuum routing. ( I do not have the TE system hooked up so no air bypass valve to worry about.)
The back fitting on mine shows the automatic transmission modulator line going to the back fitting. (per the 1968 Lincoln Mercury Service Department Vacuum System Diagnosis Guide p.33) The other back fitting has the a/c speed control, and headlight switch vacuum lines going there. Maybe even the tilt column line as well through various tee fittings. The other obvious connection is the brake booster metal line to the rear fitting.
The front fitting is more puzzling - I have the single diaphragm distributor advance that I think should be direct to to the carburetor passenger side. A dual advance diaphragm (S) fitting would connect to the front fitting as well as the air cleaner vacuum override from some pictures I have found on-line for a 1968 GT 390.
The 1968 GT also has a hollow carburetor stud on the driver’s side with a vacuum line hooked there. (This may be where the transmission modulator line goes)?
I am not sure about the front fitting for a 1967 GT 390 as there is no air cleaner vacuum lines to connect with the open air cleaner design.
Thanks for the response…My GT is an automatic as well, but no speed control or A/C. My thought was to connect both the hide-aways and tilt-away vacuum lines to the front fitting. That would leave one rear fitting for the tx modulator and a spare (in my case). What I am unsure about is the vacuum fitting on the carb spacer (as shown), and also the fact that the brake booster is shown connected (indirectly) to the PCV. I was under the impression that this is not recommended. I really have to wonder what, if anything, I am missing here…?
The 68 GT 390 spacer doesn’t have the port like 67. Maybe it is plugged. Transmission modulator line should be to a fitting on the intake manifold not carburetor.
Understood and agreed…what are your thoughts on the brake booster connection to the PCV? Are you setting up your system like the diagram I have? That is, with the PCV tube as depicted?
I have a 68 GT and my connections are very similar to the 67 and I will connect it back to the rear vacuum port as pictured.
Charlie
Are you referring to the brake booster line?
Yes. Mine comes off that connection.
OK…I will assume for now then that the engineers at Ford had it right, unless someone else can convince me otherwise. Thanks for the responses. I appreciate it.
Dennis
There is a pot metal “double F” fitting on cars equipped with cruise control. The headlights, AC vacuum supply, and tilt all connect to three sides of the “double F” fitting, while the forward fitting connects to the brass portion of the rear intake / brake booster / PCV fitting. The automatic transmission modulator connects to the smaller of the two fittings.
You are probably missing the “double F”. It is essentially to tee fittings, which is what you can do.
The two smaller front vacuum ports are for the distributor vacuum thermostatic control and the smog diverter valve on all 390GT’s in 1968.
The air cleaner vacuum motor connects to a hollow carburetor stud that you can also buy from Mansfield Mustang.
Great info!! Thanks Royce
Charlie
Royce,
Thanks for the clarification! It is sometimes difficult to understand some of the factory drawings when they don’t fit your exact equipment/vacuum systems.
Is there a source for the PCV-1 hose? That is the last part of the puzzle that I need.
