North American Turbocoupe Organization



Gillis valve question
Noname
Guest
#1
I installed a Gillis valve in my 88 T/C 5 speed and tried to adjust it but I keep getting the over boost warning. I have it backed off 6-8 threads but at WOT it still goes past 18# and the warning comes on.(no buzzer) I don't mind, but I don't want to wreck anything. Do I need to back off more or is there another problem?
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Pete D Offline
Administrator
#2
Jim, Are you sure you have it hooked up correctly? Back the valve out a couple more turns and if that doesn't result in a reduction, I would review the install instructions. Two possibilities are the hoses are reversed at the valve, or the circuit to the WGA is not completed. As it stands now you are getting 17 psi or more of boost if the warning buzzer is going off. This makes me think that boost is not getting to the WGA to open the wastegate,especially if you have the valve backed off 6 or 7 threads.

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88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS.
Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges. New engine shortly, ported head and
manifolds, polished and cc'd chambers, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, Walbro 190 pump and T-3 for starters. KB subs
and jack rails.
Pete Dunham


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Noname
Guest
#3
Pete, I took off the double fitting on the compressor housing and installed a plug. I ran a hose from the waste gate to the side of the gillis valve and one from the bottom of the gillis to the vacuum tree on the drivers side fire wall ( the one marked with a T ). Next I un hooked the line coming from the BCS to the fitting on top of the inllet to the turbo and adjusted it so 5 threads showed. I played around with it, closed it a little, found I went the wrong way, and opened it back up. I'm at work so I'll double check it tomorrow and see what happens. Thanks for all your help.

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88 Turbo Coupe 5 speed
77,000 miles
K&N filter
3"DP and 2 1\2" Dynomax
Gillis Valve
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GaryS#2 Offline
Posting Freak
#4
[QUOTE]Originally posted by Jim Coher:
[B]Pete, I took off the double fitting on the compressor housing and installed a plug.

If you mean the Y that comes out the housing then that is where your problem is.The pressure comes out there to open the waste gate.
It does on mine anyhow?
Grocery Getter/Rice Cooker.
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Noname
Guest
#5
The fitting I took out was in the top of the compressor. It had two hoses hooked to it. One went to the waste gate and the other went to the top port on the BCS. There was a plug that came with the kit.
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Dudleynascar Offline
Junior Member
#6
Hey, i have a problem with my Gills valve too. I am getting 15 psi. boost with it adjusted but i only have like 2 threads left showing. I was told that the valve can be adjusted to somewhere near 23 psi, obviously not to mine (yet) as it is still pretty much stock, but i cant see how its possible since it only has 2 threads showing to adjust it. I have checked the instructions over and i have it all connected correctly. Thanks, Travis
that's racin' (phrase): Expresses frustration or emotion. When a small part costing just a few dollars fails and stops a $150,000 race car, that's racin'.

1988 Blue T-Coupe, Stock, 175k miles
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1987tc Offline
Senior Member
#7
Keep in mind that there is more then one thing that can determine how much boost you make. The condition of your turbo, and of the wastegate and actuater. Not to mention your exhaust system.

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1987 TC:
Hurst compition plus shifter,K&N cone,roller cam,custom single exhaust,Gillis valve,H&R springs,KYB shocks,struts and quads.
3.73 rear.
Tubular rear control arms and Kenny Brown trac kit brackets. soon to come, Installation of Caster camber plates and a custom built roll cage.
Wes Arnett
Linton Indiana
Sold my Turbocoupe. It went to a good home.
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Nate K Offline
Posting Freak
#8
Dudleynascar...(and others) Yes the Gillis valve is capable of psi's in the 20's, but not with your stock turbo. You will be limited to about 18 max psi before you start getting detonation. If you're taken your psi readings from the factory gauge, they tend to be inaccurate, some times as much as 5 psi. If you don't have one yet, it's recommended to get an aftermarket gauge such as an Autometer that reads to 20 or 30 psi so you can get an accurate reading and then dial the valve in accordingly.

Keep in mind, it's not uncommon for the Gillis valve to develope an oily film inside causing the check ball to stick. Take the valve apart, clean all parts with brake cleaner, then reassemble. It helps to mark the threads with a marker or tape so you can return to the previous settings, however you will need to readjust accordingly.

Check all the tubing for any kinks,bends, or possible leaks.

As stated from others, the amount of boost available is determined by several factors, the valve only regulates the amount, so if you don't have the boost available then it's not the valve that is the problem.

Good luck
NATO Member
3 - 88 TURBOCOUPES www.turbotbird.com/showroom/nk_88tc.html
90 Mustang LX 5.0L Notch

Cars I wish I still owned:
69 Coronet 440
70 Torino 351C
79 Bronco 351M/400 on 35's
79 Trans Am 403 (6.6L)
88 Cougar XR7 5.0L
93 F150 Flareside Mark III Custom 5.0L
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Dan E Offline
Posting Freak
#9
Here is the Gillis Installation...

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Dan Eaves
88TC 5spd, Shortblock with Crower 5.5" Sportsman Rods and Short Wiseco Pistons bored .030" Over, Ported Head with Polished Combustion Chambers, Gutted & Polished Upper, Ported & Polished Lower, Polished T/B, Ported E6, SVO T3 Turbo, 3" DP w/No Cat, RR Cam, Adjustable Cam Sprocket, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pullies, and the DAMN Heater Core is new too !
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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Noname
Guest
#10
Dan, I have it hooked up the same as in the diagram. Does it matter what port I hooked in to on the vacuum tree? I hooked it in the one marked with a T. I backed off as far as the threads would allow and I still get the over boost warning. Maybe the waste gate actuator isn't working. It seemed OK before. One thing I don't understand, maybe someone could shed some light on the subject. When the turbo is putting out say 15 psi of boost, is the whole vacuum system pressurized to 15 psi? If that's the case, how does vacuum operated controls work if there is no vacuum?

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88 Turbo Coupe 5 speed
77,000 miles
K&N filter
3"DP and 2 1\2" Dynomax
Gillis Valve
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