North American Turbocoupe Organization

Gillis valve install double check
DRADIS Offline
Junior Member
As ive mentioned in previous threads, ive not worked with turbos in many many years and my knowledge is limited. I have an 87 TC, currently the only mod is that i have a K&N Cone filter installed and the airbox is gone.

I'm reading the instructions on here as well as that came with the gillis valve and before i go and mess it all up i wanted to write up what i *think* i should be doing. Please let me know if i have something backwards. I may be the only person in history to ever install a mass airflow sensor backwards on a 94 probe.

Vacuum tube will be cut to length,

The valve seems self explanatory. Inlet to the vacuum tree (have an unused port capped off, will uncap and hook up hose)
Outlet will vacuum tube hook to the Waste gate, the vacuum hose that is on the angled vacuum port.

I did not get a hex plug, but i did get a square NPT plug in my kit. I assume it works the same. This goes to the compressor outlet where the 2 port fitting used to be. (i assume i just save this fitting in case i go back to stock?)

the vacuum port cap, i assume that goes to the compressor inlet port

The straight line vac hose connector goes on the hose that runs from the wastegate to where the 2 port fitting was. I essentially pull the hose off from the 2 port fitting and put the connector on it, which then i connect the new vacuum hose that runs directly to the gillis valve outlet.

OK now to question time;
zip ties, am i supposed to use the zip ties as a hose clamp? I assume i should supply my own hose clamps and these are used for holding the hoses in place.

The hoses from the BCS, if i read right i should just secure them somewhere and leave them?

Last question, it was dark when i did the K&N Swap and just remembered something. I won't get to tinker with the TC until sunday but when i swapped out the airbox, The elbow coming out of the VAM that ran to the airbox was removed and in the elbow there was a small air hose on the bottom that ran to a box under my bumper... What is this box? I feel silly for having to ask, but i have no idea and couldn't get a good look at it in the dark (as i was doing the cone to VAM setup, it got completely dark and started a downpour).
1987 Thunderbird Turbo Coupe

blackbird87 Offline
Box is the evap for gas tank. The line on left goes to t fitting. The other goes to wastegate.
1988 Turbo Coupe 5spd stock. 1987 Turbocoupe 5spd,Totalled.

DRADIS Offline
Junior Member
Ahh evap. Ok, i was curious as to no mention of it when swapping to the K&N cone. We do not have emissions testing in TN yet, but would it be beneficial to fabricate a hose that would place the evac in between the k&n and the VAM? For reburn purposes?
1987 Thunderbird Turbo Coupe

Pete D Offline
Yes the zip ties are for positioning the lines. Putting in your own hose clamps is not a bad idea.

Just get the hoses from the stock BCS out of the way

Hey Blackbird, is the Corvair yours?
Pete Dunham


DRADIS Offline
Junior Member
done and done. WOW is all i can say. Better boost management, boost builds at lower RPM, it's like driving a new car.
1987 Thunderbird Turbo Coupe

Jeff K Offline
Yup! MBC is about the single best mod you can do.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized

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